History of the periodic table of chemical elements
1669 German merchant and amateur alchemist Hennig Brand attempted to created a Philosopher’s Stone; an object that supposedly could turn metals into pure gold. He heated residues from boiled urine, and a liquid dropped out and burst into flames. This was the first discovery of phosphorus.
In 1680 Robert Boyle also discovered phosphorus, and it became public.
In 1809 at least 47 elements were discovered, and scientists began to see patterns in the characteristics.
In 1863 English chemist John Newlands divided the then discovered 56 elements into 11 groups, based on characteristics.
DIMITRI MENDELEEV
1869 Russian chemist Dimitri Mendeleev started the development of the periodic table, arranging chemical elements by atomic mass. He predicted the discovery of other elements, and left spaces open in his periodic table for them.
In 1886 French physicist Antoine Bequerel first discovered radioactivity. Thomson student from New Zealand Ernest Rutherford named three types of radiation; alpha, beta and gamma rays. Marie and Pierre Curie started working on the radiation of uranium and thorium, and subsequently discovered radium and polonium. They discovered that beta particles were negatively charged.
In 1894 Sir William Ramsay and Lord Rayleigh discovered the noble gases, which were added to the periodic table as group 0.
In 1897 English physicist J. J. Thomson first discovered electrons; small negatively charged particles in an atom. John Townsend and Robert Millikan determined their exact charge and mass.
In 1900 Bequerel discovered that electrons and beta particles as identified by the Curies are the same thing.
In 1903Rutherford announced that radioactivity is caused by the breakdown of atoms.
In 1911 Rutherford and German physicist Hans Geiger discovered that electrons orbit the nucleus of an atom.
In 1913 Bohr discovered that electrons move around a nucleus in discrete energy called orbitals. Radiation is emitted during movement from one orbital to another.
In 1914 Rutherford first identified protons in the atomic nucleus. He also transmutated a nitrogen atom into an oxygen atom for the first time. English physicist Henry Moseley provided atomic numbers, based on the number of electrons in an atom, rather than based on atomic mass.
In 1932 James Chadwick first discovered neutrons, and isotopes were identified. This was the complete basis for the periodic table. In that same year Englishman Cockroft and the Irishman Walton first split an atom by bombarding lithium in a particle accelerator, changing it to two helium nuclei.
In 1945Glenn Seaborg identified lanthanides and actinides (atomic number >92), which are usually placed below the periodic table.
MODERN PERIODICTABLE
Reading the table
The periodic table contains an enormous amount of important information:
Atomic number: The number of protons in an atom is referred to as the atomic number of that element. The number of protons defines what element it is and also determines the chemical behavior of the element. For example, carbon atoms have six protons, hydrogen atoms have one, and oxygen atoms have eight.
Atomic symbol: The atomic symbol (or element symbol) is an abbreviation chosen to represent an element ("C" for carbon, "H" for hydrogen and "O" for oxygen, etc.). These symbols are used internationally and are sometimes unexpected. For example, the symbol for tungsten is "W" because another name for that element is wolfram. Also, the atomic symbol for gold if "Au" because the word for gold in Latin is aurum.
Atomic weight: The standard atomic weight of an element is the average mass of the element in atomic mass units (amu). Individual atoms always have an integer number of atomic mass units; however, the atomic mass on the periodic table is stated as a decimal number because it is an average of the various isotopes of an element. The average number of neutrons for an element can be found by subtracting the number of protons (atomic number) from the atomic mass.
Atomic weight for elements 93-118: For naturally occurring elements, the atomic weight is calculated from averaging the weights of the natural abundances of the isotopes of that element. However, for lab-created trans-uranium elements — elements with atomic numbers higher than 92 — there is no "natural" abundance. The convention is to list the atomic weight of the longest-lived isotope in the periodic table. These atomic weights should be considered provisional since a new isotope with a longer half-life could be produced in the future.
Within this category are the superheavy elements, or those with atomic numbers above 104. The larger the atom's nucleus — which increases with the number of protons inside — the more unstable that element is, generally. As such, these outsized elements are fleeting, lasting mere milliseconds before decaying into lighter elements, according to the International Union of Pure and Applied Chemistry (IUPAC). For instance, superheavy elements 113, 115, 117 and 118 were verified by the IUPAC in December 2015, completing the seventh row, or period, on the table. Several different labs produced the superheavy elements. The atomic numbers, temporary names and official names are:
If the periodic table were a city, the s-block would be a small neighborhood filled with extremely similar houses and properties. Within the periodic table, the s-block is located to the far left and includes all of the elements in the first two columns (columns 1 and 2) plus helium, which is located in the top right corner in column 8A (column 18 on some versions of the periodic table). In the periodic table below, the s-block is colored pink.
The s-block elements are the 14 elements contained within these columns. All of the s-block elements are unified by the fact that their valence electrons (outermost electrons) are in an s orbital. The s orbital is spherical and can be occupied by a maximum of two electrons. Elements in column 1 have one electron in the sorbital, and elements in column 2 (plus helium) have two electrons in the s orbital.
The s-block elements include hydrogen (H), helium (He), lithium (Li), beryllium (Be), sodium (Na), magnesium (Mg), potassium (K), calcium (Ca), rubidium (Rb), strontium (Sr), cesium (Cs), barium (Ba), francium (Fr) and radium (Ra). The periodic table shows exactly where these elements are within the s-block.
Properties of S-Block Elements
If the elements were houses in our hypothetical s-block neighborhood, they would be very uniform, each one only slightly different than the other. This is markedly different compared to the other neighborhoods on the periodic table, which have a wider variety of houses in many shapes, sizes and colors.
All of the s-block elements are metals. In general, they are shiny, silvery, good conductors of heat and electricity and lose their valence electrons easily. In fact, they lose their trademark s orbital valence electrons so easily that the s-block elements are considered to be some of the most reactive elements on the periodic table.
Sodium, an s-block element, is a silvery and soft metal.
The elements in column 1, known collectively as the alkali metals (except hydrogen), always lose their one valence electron to make a +1 ion. These metals are characterized by being silvery, very soft, not very dense and having low melting points. These metals react extremely vigorously with water and even oxygen to produce energy and flammable hydrogen gas. They are kept in mineral oil to reduce the chance of an unwanted reaction or worse, an unwanted explosion.
Like a few other elements in the s-block, potassium reacts energetically with water.
The branch of science concerned with the substances of which matter is composed, the investigation of their properties and reactions, and the use of such reactions to form new substances. Chemistry is the science of matter. This may sound simple, but chemistry is a complex and broad topic that broaches a wide variety of fields. From the core of the earth to the farthest reaches of the universe, chemistry is everything and everywhere.
~~Chemistry is the study of matter, including its composition, properties, and structure; how it changes; and how it interacts with energy. This is a pretty simple definition that sums up what is actually a complex and fascinating subject. If you have ever asked why or how something is in the natural world, odds are good that your question and the answer were related to chemistry.
For instance, why is the sky blue? Colors depend on the chemical makeup of substances and what kind of light they reflect. How does an insect walk across the surface of a pond without falling through? The unique properties of water give it a high surface tension, which means that small objects can rest on it without sinking. Chemistry is all around, and anything related to matter involves chemistry.
Since chemistry is such a broad and vast subject, we can divide it up into more manageable topics to help us more accurately. For example, organic and inorganic chemistry divide up all matter into two categories of study. Organic chemistry is the study of the carbon compounds that make up living things. Inorganic chemistry is the study of everything else.
Biochemistry
Biochemistry is the study of the chemical processes that go on in living things and includes the large biological molecules, like DNA, proteins, carbohydrates, and lipids.
Analytical Chemistry
Analytical chemistry is the analysis of chemicals, their properties, and how they react. It also involves the development of tools and methods for doing this analytical work. Analytical chemistry is used by chemists of all disciplines, but some professionals focus solely on the development of analytical methods.
Physical Chemistry
Physical chemistry is the study of physical principles that underlie atoms and compounds, in other words, the physics of chemical compounds. This means that physical chemists examine how particles move, how energy is involved in reactions, the speed at which reactions occur, and how light and energy interact with matter.
Organic, inorganic, analytical, and physical chemistry, along with biochemistry, represent the main topics of study by chemists. There's plenty of overlap. For instance, an organic chemist might be interested in the rate of a reaction of an organic compound, which involves physical chemistry. Or, an inorganic chemist may need an analytical method to investigate the crystal structure of an inorganic compound.
In addition to the main categories of chemistry, there are countless subcategories and specializations that can be named. For example, environmental chemistry is the study of chemical processes in the environment. An environmental chemist might study pollutants in the atmosphere. A geochemist studies the composition and chemical processes of the earth, rocks, and soil, and might work for a petrochemical company. A medicinal chemiststudies drugs and how they work to treat diseases. They often work for pharmaceutical companies.
4)potassium permaganate combined with propane 1,2,3ol(glycerol)
4) -128°f dry ice
5) aluminium bromide (Albr3)
Reaction between aluminium and bromine
6) The gallium metal tottaly safe to touch and play with it
It's soft silvery metal that solid at room temperature
7)
The flame on the candle needs the gas oxygen to keep burning. Once we place the glass container over the lit candle, the oxygen inside begins to get used up. Once all the oxygen has been used, the flame will go out.🕯
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However, there are still other gases remaining inside the glass (nitrogen, argon, carbon dioxide, etc.). But these gases have lower pressure inside the glass when compared to the higher atmospheric pressure on the outside of the glass.🔥
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This higher atmospheric pressure from the outside pushes the water from the plate up and into the glass. One more thing is happening here to make the water rise into the glass. When we cover the lit candle with the glass, it heats the air inside the glass. The heated air expands. As it expands it comes out from under the glass container.😳
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You might observe some bubbles after you put the glass over the candle. That's the hot air escaping. Once the flame dies out, the air inside the glass begins to cool down. As it cools, the air contracts inside the glass container. This contraction pulls the water from outside on the plate into the glass.⚗
This alphabetical chemistry dictionary offers definitions and examples of important chemistry and chemical engineering terms. For each term, a brief definition is given. Each link leads to a more comprehensive discussion of the word.
A- Absolute Alcohol to Azimuthal Quantum Number
absolute alcohol - common name for high purity ethanol or ethyl alcohol.
absolute error - expression of the uncertainty or inaccuracy of a measurement.
absolute uncertainty - the uncertainty of a scientific measurement, given in the same units as the measurement.
absolute zero - the lowest possible state at which matter can exist, 0 K or -273.15°C.
absorbance - measure of the amount of light absorbed by a sample.
absorption - process by which atoms, ions, or molecules enter a bulk phase.
absorption spectroscopy - technique used to determine concentration and structure of a sample based on which wavelengths of liquid are absorbed.
absorption spectrum - graph of amount of absorption as a function of wavelength.
absorptivity - absorption cross section of extinction coefficient, which is the absorbance of a solution per unit path length and concentration.
accuracy - the closeness of a measurement to a true or accepted value.
acid - a chemical species that accepts electrons or donate protons or hydrogen ions.
acid anhydride - a nonmetal oxide that reacts with water to form an acidic solution.
acid-base indicator - a weak acid or weak base that changes color when the concentration of hydrogen or hydroxide ions changes in an aqueous solution.
acid-base titration - a procedure to find the concentration of an acid or base by reacting a known concentration with the unknown until the equivalence point is reached.
acidic solution - an aqueous solution with a pH less than 7.0.
actinides - Usually, the actinides are considered to be elements 90 (thorium) through 103 (lawrencium). Otherwise, the actinides are defined according to their common properties.
actinium - the name for the element with atomic number 89 and is represented by the symbol Ac. It is a member of the actinide group.
activated complex - an intermediate state at the maximum energy point on the reaction path that occurs as reactants are being converted into product in a chemical reaction.
activation energy - Ea - the minimum amount of energy needed for a chemical reaction to occur.
active transport - the movement of molecules or ions from a region of lower concentration to higher concentration; requires energy
activity series - list of metals ranked in order of decreasing activity, used to predict which metals displace others in aqueous solutions.
actual yield - the quantity of product experimentally obtained from a chemical reaction.
acyl group - a functional group with the formula RCO- where R is bound to carbon via a single bond.
adsorption - the adhesion of a chemical species onto a surface
adulterant - a chemical that acts as a contaminant in the context of another substance's purity.
aether - a medium believed to carry light waves in the 18th and 19th century.
air - the mixture of gases that make up the Earth's atmosphere, consisting mainly of nitrogen, with oxygen, water vapor, argon, and carbon dioxide.
alchemy -Several definitions of alchemy exist. Originally, alchemy was an ancient tradition of sacred chemistry used to discern the spiritual and temporal nature of reality, its structure, laws, and functions.
alcohol - a substance that contains an -OH group attached to a hydrocarbon.
anode - electron where oxidation occurs; positive charged anode
antibonding orbital - molecular orbital with an electron outside the region between the two nuclei.
anti-Markovnikov addition - an addition reaction between an electrophilic compound HX and either an alkene or alkyne in which the hydrogen atom bonds to the carbon with the least number of hydrogen atoms and X bonds to the other carbon.
antimony - Antimony is the name for the element with atomic number 36 and is represented by the symbol Kr. It is a member of the metalloid group.
anti-periplanar - periplanar conformation where the dihedral atom between atoms is between 150° and 180°.
aqua regia - mixture of hydrochloric and nitric acids, capable of dissolving gold, platinum, and palladium.
argon - Argon is the name for the element with atomic number 18 and is represented by the symbol Ar. It is a member of the noble gases group.
aromatic compound - an organic molecule that contains a benzene ring.
Arrhenius acid - species that dissociates in water to form protons or hydrogen ions.
Arrhenius base - species that increases the number of hydroxide ions when added to water.
arsenic - metalloid with element symbol As and atomic number 33.
aryl - a functional group derived from a simple aromatic ring when one hydrogen is removed from the ring.
astatine - Astatine is the name for the element with atomic number 85 and is represented by the symbol At. It is a member of the halogen group.
atom - the defining unit of an element, which cannot be subdivided using chemical means.
atomic mass - average mass of atoms of an element.
atomic mass unit (amu) - 1/12th the mass of an unbound atom of carbon-12, used to represent atomic and molecular masses.
atomic number - the number of protons in the nucleus of an atom of an element.
atomic radius - value used to describe the size of an atom, usually half the distance between two atoms just touching each other.
atomic solid - solid in which atoms are bonded to other atoms of the same type.
atomic volume - volume occupied by one mole of an element at room temperature.
atomic weight - average mass of atoms of an element.
atmosphere - surrounding gases, such as the gases surrounding a planet that are held in place by gravity.
ATP - ATP is the acronym for the molecule adenosine triphosphate.
Aufbau principle - idea that electrons are added to orbitals as protons are added to an atom.
austenite - the face-centered cubic crystalline form of iron.
Avogadro's Law - relation that states equal volumes of all gases contain the same number of molecules at the same pressure and temperature.
Avogadro's number - the number of particles in one mole of a substance; 6.0221 x 1023
azeotrope - a solution that retains its chemical composition when distilled.
azimuthal quantum number - the quantum number associated with the angular momentum of an electron, determining the shape of its orbital.
B definitions - Background Radiation to Buffer
background radiation - radiation from external sources, typically from cosmic radiation and radioisotope decay.
back titration - titration in which the analyte concentration is determined by reacting it with a known quantity of excess reagent.
balanced equation - chemical equation in which the number and type of atoms and the electric charge is the same on both the reactant and product sides of the equation.
Balmer series - the part of the hydrogen emission spectrum for electron transitions n=2 and n>2, There are four lines in the visible spectrum.
barium - alkaline earth metal with element symbol Ba and atomic number 56.
barometer - instrument used to measure atmospheric pressure.
base - chemical species that either accepts protons or else donates electrons or hydroxide ions.
base anhydride (basic anhydride) - a metal oxide formed from the reaction between water and a basic solution.
base metal - any metal besides a precious or noble metal used for jewelry or in industry.
bond energy - quantity of energy needed to break one mole of molecules into component atoms.
bond enthalpy - enthalpy change resulting when one mole of bonds in a species are broken at 298 K.
bond length - the equilibrium distance between atomic nuclei or groups of nuclei that share a chemical bond.
bond order - a measure of the number of electrons involved in chemical bonds between two atoms in a molecule; usually equal to the number of bonds between the atoms.
boron - Boron is the name for the element with atomic number 5 and is represented by the symbol B. It is a member of the semimetal group.
Boyle's law - ideal gas law that states the volume of a gas is inversely proportional to its absolute pressure, assuming constant temperature.
branched chain alkane - an alkane with alkyl groups bonded to the central carbon chain. The molecules are branched, but all C-C bonds are single bonds.
bronze - Bronze is an alloy of copper, usually containing tin as its main addition.
buffer - either a weak acid and its salt or else a weak base and its salt that form an aqueous solution that resists pH change
C - Cadmium to Current
cadmium - Cadmium is the name for the element with atomic number 48 and is represented by the symbol Cd. It is a member of the transition metals group.
caffeine - Caffeine is a chemical substance naturally found in tea and coffee and added to colas.
calcium - Calcium is the name for the element with atomic number 20 and is represented by the symbol Ca. It is a member of the alkaline earth metal group.
calorie- unit of thermal energy; the amount of energy required to raise the temperature of 1 gram of water 1 degree C or K at standard pressure.
calorimeter - instrument designed to measure heat flow of a chemical reaction or physical change.
capillary action - the spontaneous floe of liquid into a narrow tube or porous material.
carbon - Carbon is the name for the element with atomic number 6 and is represented by the symbol C. It is a member of the nonmetal group.
carbonate - an ion consisting of one carbon bonded to three oxygen atoms (CO32-) or a compound containing this ion.
carbonyl - functional group consisting of a carbon atom double bonded to oxygen, C=O.
carboxyl group - functional group consisting of a carbon double bonded to oxygen and single bonded to a hydroxyl (-COOH).
catalyst - substance that increases the chemical reaction rate by decreasing its activation energy.
catenation - binding of an element to itself via covalent bonds, forming a chain or ring
cathode - electrode where reduction occurs; usually the negative electrode.
cathode ray tube - a vacuum tube with a source of electrons, a fluorescent screen, and means of accelerating and deflecting the electron beam.
chemical change - process by which one or more substances are altered to form new substances.
chemical energy - energy contained in the internal structure of an atom or molecule.
chemical equation - description of a chemical reaction, including the reactants, products, and direction of the reaction.
chemical equilibrium - state of a chemical reaction where the concentration of the reactants and products remains stable over time.
chemical formula - expression which states the number and type of atoms in a molecule.
chemical kinetics - the study of chemical processes and rates of reactions.
chemical property - characteristic which may be observed when matter undergoes a chemical change.
chemical reaction - a chemical change in which reactants form one or more new products.
chemical symbol - one- or two-letter representation of a chemical element (e.g., H, Al).
chemiluminescence - light emitted as a result of a chemical reaction
chemistry - study of matter and energy and the interactions between them
Cherenkov radiation - Cherenkov radiation is the electromagnetic radiation emitted when a charged particle moves through a dielectric medium faster than the velocity of light in the medium.
chiral center - the atom in a molecule bonded to four chemical species, allowing optical isomerism.
chirality - Chirality or chiral describes a nonsuperimposable mirror image, like left and right hands. Usually in chemistry the term is used to describe a pair of molecules that have the same formulas, but form a pair of structures.
chlorine - halogen with atomic number 17 and element symbol Cl.
chlorofluorocarbon - A chlorofluorocarbon or CFC is a compound that contains atoms of chlorine, fluorine, and carbon.
chromatography - group of techniques used to separate mixture components by passing the mixture through a stationary phase.
chromium - Chromium is the name for the element with atomic number 24 and is represented by the symbol Cr. It is a member of the transition metals group.
closed system - thermodynamic system in which mass is conserved within the system, but energy can freely enter or exit.
coagulation - the gelling or clumping of particles, usually in a colloid.
cobalt - transition metal that is atomic number 27 with element symbol Co.
coenzyme - substance that works with an enzyme to aid its function or initiate its action.
cohesion - measure of how well molecules stick to each other or group together.
collagen - an important family of proteins found in humans and other animals, found in skin, cartilage, blood vessels, and tendons.
colligative properties - properties of a solution that depend on the number of particles in a volume of solvent.
colloid - a homogenous mixture in which dispersed particles do not settle out.
combined gas law - law which states the ratio of the product of pressure and volume, divided by the absolute temperature, is a constant value.
combination reaction - reaction in which two reactants combine to form a single product.
combustion - chemical reaction between a fuel and oxidizer that yields energy (usually heat and light).
common-ion effect - suppressing effect an electrolyte has on the ionization of another electrolyte that shares a common ion.
compound - chemical species formed when two or more atoms form a chemical bond.
complex ion - ion in which a central metal ion is bonded to one or more ions or molecules.
concentrated - having a large ratio of solute to solvent.
concentration - an expression of the quantity of a substance in a defined volume.
condensation - state of matter change from vapor phase to liquid phase.
condensation reaction - chemical reaction in which one of the products is water or ammonia, also known as a dehydration reaction.
condensed formula - chemical formula in which atom symbols are listed in the order they appear in the molecular structure, with limited bond dashes.
conductor - material which permits the flow of energy (e.g., electrical conductor, thermal conductor).
conformer - an isomer that differs from another isomer by rotation around a single bond.
congener - member of the same group of elements of the periodic table (e.g., iodine and chlorine).
conjugate - multiple chemistry definitions, referring to Bronsted acids and bases, a compound formed by combining other compounds, or the overlap of p-orbitals across a sigma bond.
conjugate acid - HX, a compound differing from a base X by a proton.
conjugate base - the species that gains a proton in an acid-base reaction.
conservation of energy - law which states energy can change forms but may not be created or destroyed.
conservation of mass - law that states, in a closed system, matter can change forms but not be created or destroyed.
controlled variable - variable that a scientist holds constant in an experiment; the control or constant variable
conversion factor - numerical ratio that converts a measurement from one unit into another.
coordinate bond - covalent bond between two atoms in which one atom supplies both electrons for the bond.
copernicium- radioactive element with symbol Cn and atomic number 112.
copper - Copper is the name for the element with atomic number 29 and is represented by the symbol Cu. It is a member of the transition metals group.
corrosion - irreversible damage to a material or tissue due to a chemical reaction.
corrosive - having the power to cause irreversible chemical damage upon contact.
Coulomb's law - law which states the force between two charges is proportional to the quantity of both charges and inversely proportional to the square of the distance between them.
covalent bond - chemical link between atoms or ions in which the electron pairs are more or less evenly shared between them.
Dalton's Law - relation stating the total pressure of a gaseous mixture equals the sum of the partial pressure of the component gases.
darmstadtium - Darmstadtium is the name for the element with atomic number 110 and is represented by the symbol Ds. Darmstadtium was formerly known as ununnilium with symbol Uun. It is a member of the transition metals group.
dative bond - covalent bond between atoms in which one atom provides both electrons for the bond.
daughter isotope - product formed after a radioisotope (the parent) undergoes radioactive decay.
de Broglie Equation - equation describing the wave properties of matter, stated as wavelength equals Planck's constant divided by the product of mass and velocity.
decantation - method of separating mixtures by removing the liquid layer from a precipitate.
decomposition reaction - chemical reaction in which a single reactant yields two or more products.
deflagration - type of combustion in which flame propagation is less than 100 m/s and overpressure is less than 0.5 bar.
dehydration reaction - chemical reaction between two compounds in which one of the products is water.
deliquescence - process by which a soluble substance picks up water vapor from the atmosphere to form a solution.
delocalized electron - any electron in an ion, atom, or molecule that is no longer associated with a particular atom or single covalent bond.
electrical resistivity - measure of how much a material resists carrying an electrical current.
electrochemical cell - device that generates a potential difference between electrodes via chemical reactions.
electrochemistry - scientific study of reactions and species formed at the interface between an electrolyte and a conductor, where electron transfer occurs.
electromotive force - emf - the electric potential generated by either an en electrochemical cell or changing magnetic field.
electrode - the anode or cathode of an electrical cell.
electrolysis - passage of direct current through an ion-conducting solution, producing a chemical change at the electrodes.
electrolyte - a substance that forms ions in aqueous solution.
electrolytic cell - type of electrochemical cell in which the flow of electric energy from an external source enables a redox reaction.
electromagnetic radiation - light; self propagating energy that has electric and magnetic field components.
electron - stable negatively charged subatomic particle.
electron affinity - measure of the ability of an atom to accept an electron.
electron capture (EC) - form of radioactive decay in which the atomic nucleus absorbs a K or L shell electron, converting a proton into a neutron.
electron cloud - region of negative charge surrounding the atomic nucleus that has a high probability of containing electrons.
electron configuration - description of the population of the electronic energy sublevels of an atom.
electron density - representation of the probability of finding an electron in a specific region around an atom or molecule.
electron domain - the number of lone electron pairs or bond locations around an atom or molecule.
electronegativity - property of an atom that reflects its ability to attract electrons in a chemical bond.
electron pair repulsion - principle that electron pairs surrounding a central atom orient themselves as far apart as possible; used to predict geometry.
electron-sea model - model of metallic bonding in which cations are described as fixed points in a mobile sea of electrons.
electron spin - property of an electron related to its spin about an axis, described by a quantum number as either +1/2 or -1/2.
electrophile - atom or molecule that accepts an electron pair to form a covalent bond.
electroplating - process of adding a metal coat to a material by using a reduction reaction.
electrostatic forces - forces between particles due to their electrostatic charges.
enzyme- An enzyme is a protein that functions as a catalyst for a chemical reaction.
equilibrium constant - ratio of the equilibrium concentration of products raised to the power of their stoichiometric coefficients to the equilibrium concentration of the reactants raised to the power of their stoichiometric coefficients.
equivalence point - point in a titration where the titrant completely neutralizes the analyte.
erbium - Erbium is element atomic number 68 on the periodic table.
essential amino acid - amino acid needed in the diet because an organism cannot synthesize it.
ester - RCO2R′, where R is the hydrocarbon parts of the carboxylic acid and R′ is the alcohol.
ether - organic compound containing two aryl or alkyl groups bound to an oxygen, R-O-R'.
europium - Europium is the name for the element with atomic number 63 and is represented by the symbol Eu. It is a member of the lanthanide group.
eutectic - homogeneous solid mixture of at least two types of atoms or molecules that form a superlattice (usually a mix of alloys).
evaporation - process characterized by a spontaneous transition of molecules from the liquid phase to vapor phase.
excess reactant - reactant left over in a reaction because it is present in a great amount than needed to react with the limiting reactant.
excited state - atom, ion, molecule, or subatomic particle in a higher energy level than its ground state.
extensive property - property of matter that depends on the quantity of matter that is present (e.g., volume).
F - F Orbital to Fusion
f orbital - electron orbital with l = 3 for the angular momentum quantum number,
family - a group of elements that share similar properties.
Faraday constant - a physical constant equal to the electric charge of one mole of electrons, 96485.33 C/mol.
fat - triesters of glycerol and fatty acids that are soluble in organic solvents, but generally insoluble in water.
fatty acid - a carboxylic acid with a long hydrocarbon side chain.
feedstock - any unprocessed material used as a supply for a manufacturing process.
fermium - Fermium is the name for the element with atomic number 100 and is represented by the symbol Fm. It is a member of the actinide group.
first law of thermodynamics - law which states the total energy of a system and its surroundings is a constant value; the law of conservation of energy.
fire point - the lowest temperature a vapor will initiate and sustain combustion.
fission - the splitting of an atomic nucleus, which results in two or more lighter nuclei and a release of energy.
flame test - an analytical technique used to identify ions based on their emission spectrum in a flame.
flammable - easily ignited or capable of sustained combustion.
fluid - a substance that flows under applied shear stress, including liquids, gases, and plasma.
fluorescence - luminescence released when an atom absorbs electromagnetic radiation and emits a photon when the electron falls to a lower energy state.
foam - a substance containing gas bubbles trapped within a liquid or solid.
force - a push or pull on a mass, with both magnitude and direction (vector).
formal charge - the difference between the number of valence electrons of an atom and the number of electrons associated with the atom (e.g., in a chemical bond).
formula mass or formula weight - the sum of the atomic weights of the atoms in a compound's empirical formula.
fractional distillation - process which separates components of a mixture according to their boiling points.
francium - alkali metal with element symbol Fr and atomic number 87.
free energy - the amount of internal energy of a system that is available to do work.
free radical - an atom or molecule with an unpaired electron.
freezing - process in which a liquid changes to a solid.
freezing point - temperature at which a liquid transitions to a solid (not always the same as melting point).
freezing point depression - lowering the freezing point of a liquid by adding another compound to it.
frequency - number of times a point on a wave passes a reference point in one second.
functional groups or functional moiety - group of atoms in a molecule that are responsible for characteristic reactions and properties.
fusion - combining light atomic nuclei to form a heavier nucleus, accompanied by the release of energy.
G - Gadolinium to Group
gadolinium - rare earth metal with element symbol Gd and atomic number 64.
gallium - metal with element symbol Ga and atomic number 31.
galvanic cell - electrochemical cell where reactions between dissimilar conductors occur through a salt bridge and electrolyte.
gamma radiation - high energy ionizing photons, originating from the atomic nucleus.
gas - state of matter characterized by having neither a defined shape nor defined volume.
gas constant (R) - the constant in the Ideal Gas Law; R = 8.3145 J/mol·K.
Gay-Lussac's law - form of the ideal gas law that states the pressure of an ideal gas is directly proportional to its absolute (Kelvin) temperature when volume is held constant.
gel - a type of sol where the solid particles are held in a mesh to form a rigid or semi-rigid mixture.
geometric isomer - molecules with the same number and type of atoms as each other, but with different geometrical configurations. Also called cis-trans or configurational isomerism.
germanium - metalloid with element symbol Ge and atomic number 32.
Gibbs free energy - a measure of the potential for reversible or maximum work done by a system at constant pressure and temperature.
glycosidic bond - a covalent bond between a carbohydrate and a functional group or another molecule.
gold - yellow-colored transition metal with element symbol Au and atomic number 79.
Graham's Law - relation stating the rate of effusion of a gas is inversely proportional to the square root of its molecular mass or density.
grain alcohol - purified form of ethyl alcohol made from distilling fermented grain.
gram - unit of mass equal to the mass of one cubic centimeter of water at 4°C.
gram molecular mass - the mass in grams of one mole of a molecular substance.
gravimetric analysis - a set of quantitative analytical techniques based on measurement of a sample's mass.
green chemistry - branch of chemistry concerned with lessening the environmental effect of chemicals, including development of new materials and processes.
ground state - the lowest energy state of an atom, ion, molecule, or subatomic particle.
group- a vertical column on the periodic table consisting of elements that share periodic properties.
H - Haber Process to Hypothesis
Haber process - method of making ammonia or fixing nitrogen by reacting nitrogen and hydrogen gas
hafnium - transition metal with element symbol Hf and atomic number 72.
half-cell - half of an electrolytic or voltaic cell, serving as the site of either oxidation or reduction.
half-life (t1/2) - time required to convert half of the reactant to a product or the time required for half of a radioactive isotope to decay into its daughter isotope.
halide ion - a singlet halogen atom, which has a charge of -1 (e.g., Cl-)
halogen - an element in Group VIIA of the periodic table (e.g., Br, Cl).
hard water - water that contains high amounts of calcium and/or magnesium cations.
hassium - transition metal that is atomic number 108 with element symbol Hs.
heat - energy that flows between matter samples because of a temperature difference.
heat capacity - quantity of heat needed to raise the temperature of a sample by a specified amount.
heat of formation ( ΔHf) - amount of heat absorbed or released during formation of a pure substance from its elements at constant pressure.
heat of fusion ( ΔHfus) - the change in enthalpy (heat) for the conversion of one gram or mole of a solid to a liquid at constant temperature and pressure.
heavy metal - a dense metal that is toxic at low concentrations.
Heisenberg uncertainty principle - principle that states it is impossible to determine both the position and momentum of a particle at once with perfect accuracy.
helium - Helium is the name for the element with atomic number 2 and is represented by the symbol He. It is a member of the noble gases group.
Henderson-Hasselbalch equation - an approximation that relates the pH or pOH of a solution, the pKa or pKb, and the ratio of concentration of dissociated species.
Henry's Law - law that states the mass of a gas that will dissolve into solution is directly proportional to the partial pressure of the gas above the solution.
Hess's Law - law that states the energy change in an overall reaction equals the sum of the energy changes in its individual (partial) reactions.
heterogeneous -- consisting of dissimilar components.
heterogeneous mixture - a mixture that lacks a uniform composition such that at least two components are present with identifiable properties.
heterogeneous reaction - chemical reaction in which reactants are different phases from each other.
holmium - rare earth metal with element symbol Ho and atomic number 67.
intrinsic property - property of matter that is independent of the quantity of matter present.
intermediate - substance formed in a middle step between reactants and final products.
inverse proportion - relationship between variable such that their product is a constant value.
iodine - Iodine is the name for the element with atomic number 53 and is represented by the symbol I. It is a member of the halogen group.
ion - atom or molecule which has a different number of protons than electrons and thus a net electrical charge.
ionic - pertaining to carrying a net electrical charge at the atomic or molecular level.
ionic bond - chemical link between atoms caused by electrostatic force between opposite charged ions.
ionic compound - compound formed by ions bonding together due to electrostatic forces (differing electronegativity values).
ionic equation - chemical equation in which electrolytes in aqueous solution are written as dissociated ions.
ionic radius - half the distance between two ions just touching each other.
ionization energy - energy required to completely remove an electron from a gaseous atom of ion.
iridium - Iridium is the name for the element with atomic number 77 and is represented by the symbol Ir. It is a member of the transition metals group.
iron - Iron is the name for the element with atomic number 26 and is represented by the symbol Fe. It is a member of the transition metals group.
isoelectronic - chemical species that have the same electronic structure and thus same number of valence electrons.
isolated system - thermodynamic system that can't exchange energy or matter outside of the system.
isomer - chemical species with the same number and type of atoms as another species, but a different arrangement and thus different properties.
isomerization process - protocol in which straight chain hydrocarbons are converted into branched chain hydrocarbons.
isotopes - atoms that have the same number of protons, but different numbers of neutrons and thus different atomic weight values.
IUPAC - International Union of Pure and Applied Chemistry, an authority on chemical standards.
Chemistry Definitions Starting With the Letter j
joule - SI unit of energy equal to the kinetic energy of a 1 kg mass moving at 1 m/s.
K - Kelvin Temperature to Krypton
Kelvin temperature scale - an absolute temperature scale with 100 degrees between the freezing and boiling points of water (although values are given without degrees by convention).
keratin - a fibrous protein produced by chordates. It may be found in hair, skin, claws, and wool.
ketone - compound containing a carbonyl functional group (C=O) between two groups of atoms
krypton - element 36 on the periodic table with symbol Kr.
L - Labile Complex to Lutetium
Kelvin temperature scale - an absolute temperature scale with 100 degrees between the freezing and boiling points of water (although values are given without degrees by convention).
keratin - a fibrous protein produced by chordates. It may be found in hair, skin, claws, and wool.
ketone - compound containing a carbonyl functional group (C=O) between two groups of atoms
krypton - element 36 on the periodic table with symbol Kr.
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L - Labile Complex to Lutetium
labile complex - a complex ion that quickly reaches equilibrium with ligands in the surrounding solution.
lanthanides - subset of transition metals characterized by filling of the 4f sublevel, usually atomic number 58-71.
lanthanum - element atomic number 57 with element symbol La.
lattice energy - enthalpy change of the process by which opposite-charged ions in a gas combine to form a solid ionic lattice.
law - a general rule that explains a body of scientific observations. Laws are stated in words, but expressed by mathematical equations.
Law of Chemical Equilibrium - an expression of the relationship between the concentration of reactants and products of a chemical reaction mixture at equilibrium.
Law of Combining Volumes - relation that states the volumes of gases in a chemical reaction are present in the ratio of small integers under conditions where all gases are at the same temperature and pressure.
Law of Conservation of Energy - law that states energy can neither be created nor destroyed, although it may change from one form into another.
Law of Conservation of Mass - law that states matter in a closed system may be neither created nor destroyed, although it may change forms.
Law of Constant Composition - chemistry law that states samples of a pure compound contain the same elements in the same proportions by mass.
Law of Definite Proportions - law that states all samples of a compound contain the same proportion of elements by mass.
Law of Multiple Proportions - law that states element combine in ratios of small whole numbers to form molecules.
lawrencium - actinide with element symbol Lr and atomic number 103.
lead - metal with element symbol Pb and atomic number 82.
Le Chatelier′s Principle - principle that says that equilibrium of a chemical system will shift in the direction to relieve stress.
Lewis acid - chemical species that can act as an electron pair acceptor.
Lewis base - a substance that is an electron pair donor.
Lewis acid base reaction - chemical reaction that forms at least one covalent bond between an electron pair donor (Lewis base) and electron pair acceptor (Lewis acid).
Lewis structure - representation of a molecule that uses dots to show electrons around atoms and lines to show covalent bonds.
ligand - a chemical species that donates or shares at least one electron via a covalent bond with a central ion or atom.
limiting reactant - the reactant that determines how much product may result from a chemical reaction.
lipid - class of fat-soluble molecules, also known as oils and fats
liquefaction - process of converting a material from a solid or gas phase into the liquid phase.
liquid - state of matter characterized by having a definite volume but not a definite shape.
lithium - alkali metal with atomic number 3 and element symbol Li.
litmus paper - filter paper used as a pH paper that has been treated with a water-soluble dye obtained from lichens.
London dispersion force - weak intermolecular force between atoms or molecules in close proximity to each other, due to electron repulsion.
lone pair - an electron pair in the outer shell of an atom that is not shared or bonded with another atom.
lutetium - rare earth metal with element symbol Lu and atomic number 71.
M - Macromolecule to Muriatic Acid
ond with a central ion or atom.
limiting reactant - the reactant that determines how much product may result from a chemical reaction.
lipid - class of fat-soluble molecules, also known as oils and fats
liquefaction - process of converting a material from a solid or gas phase into the liquid phase.
liquid - state of matter characterized by having a definite volume but not a definite shape.
lithium - alkali metal with atomic number 3 and element symbol Li.
litmus paper - filter paper used as a pH paper that has been treated with a water-soluble dye obtained from lichens.
London dispersion force - weak intermolecular force between atoms or molecules in close proximity to each other, due to electron repulsion.
lone pair - an electron pair in the outer shell of an atom that is not shared or bonded with another atom.
lutetium - rare earth metal with element symbol Lu and atomic number 71.
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M - Macromolecule to Muriatic Acid
macromolecule - molecule containing a very large number of atoms, usually more than 100.
Madelung's rule - rule that describes filling of electron orbitals in atoms due to shielding of nuclear charge by inner electrons.
magnesium - Magnesium is the name for the element with atomic number 12 and is represented by the symbol Mg. Magnesium is an alkaline earth metal.
main group elements - any of the elements in the s and p blocks of the periodic table.
malleable - able to be shaped or pounded with a hammer, usually applied to metals.
manganese - element with atomic number 25 and element symbol Mn.
mass - amount of matter a substance contains or property of matter that resists acceleration.
mass defect - difference between the mass of an atom and the sum of the masses of its protons, neutrons, and electrons.
mass number - whole number integer that is the sum of the number of protons and neutrons in the atomic nucleus.
mass percentage - concentration calculated as mass of a component divided by total mass of mixture or solution; w/w%.
mass spectroscopy - analytical technique used to separate and/or identify components of a mixture based on mass and electrical charge.
matter - anything that has mass and occupies volume.
measurement - quantitative or numerical data describing an object or event.
medicinal chemistry - branch of chemistry concerned with design, synthesis, and study of pharmaceuticals.
meitnerium - radioactive transition metal with element symbol Mt and atomic number 109.
melting - phase change of matter from solid to liquid.
melting point - temperature at which the solid and liquid phase of matter coexist in equilibrium.
mendelevium - actinide with atomic number 101 and element symbol Md.
meniscus - phase boundary between a liquid in a container and a gas, curved due to surface tension.
mercaptan - organic sulfur compound containing an alkyl or aryl group and a thiol group.
mercapto group - functional group consisting of a sulfur bonded to a hydrogen; -SH.
mercury - transition metal with element symbol Hg and atomic number Hg.
metabolism - set of biochemical reactions that store chemical energy and convert it into a form an organism can use.
metal - substance that has high conductivity and other metallic properties, including tendency to form cations, often identified by group on the periodic table.
metallic character - set of chemical properties associated with metals, including the ability to lose outer valence electrons to form cations.
metallic compound - chemical compound that contains one or more metal atoms.
metalloid - element with properties intermediate between those of metals and nonmetals (e.g., silicon).
meter - either (a) the base unit of length in the SI system or (b) a device used to measure a quantity.
methyl - functional group containing a carbon bonded to three hydrogen atoms, -CH3.
microliter - unit of volume that is one-millionth of a liter one cubic millimeter.
micron - unit of length equal to one-millionth of a meter; a micrometer.
mineral acid - any inorganic acid (e.g., sulfuric acid).
miscible - soluble or able to be mixed to form a solution, typically applied to fluids.
mixture - combination of two or more substances such that each retains its separate chemical identity (e.g., salt and flour).
moderator - material that slows or moderates the speed of neutrons.
Mohs scale - Mohs scale is a relative scale rating the hardness of a mineral. A mineral with a high Mohs number is able to mark a mineral with a lower Mohs number.
moiety - group of atoms in a molecule that are responsible for its characteristic chemical behavior.
molality - unit of concentration that is the moles of solute divided by the kilograms of solvent.
molar - refers to molarity (moles per liter of solution); e.g. a 6 M HCl solution has 6 moles of hydrochloric acid per liter of solution.
molar enthalpy of fusion - energy needed to change one mole of a substance from solid to liquid phase at constant pressure and temperature.
molar enthalpy of vaporization - energy needed to change one mole of liquid to the gas phase at constant pressure and temperature.
molarity - unit of concentration that is the number of moles of solute divided by the number of liters of solution.
neutralization - chemical reaction between an acid and base that results in a neutral solution.
neutron - particle in the atomic nucleus that has a mass of 1 and charge of 0.
newton (N) - SI unit of force equal to the amount of force needed to accelerate a 1 kg mass 1 m/sec2.
nickel - Nickel is the name for the element with atomic number 28 and is represented by the symbol Ni. Nickel is a member of the transition metals group.
niobium - Niobium is the name for the element with atomic number 41 and is represented by the symbol Nb. Niobium is also called Columbium and is a transition metal.
nitrogen - Nitrogen is the name for the element with atomic number 7 and is represented by the symbol N. Nitrogen is also known as azote and is a member of the nonmetal group.
nobelium - actinide with element symbol No and atomic number 102.
noble gas - element from Group 8 of the periodic table (e.g., xenon, argon).
noble gas core - shorthand notation used writing atomic electron configuration in which previous noble gas configuration is replaced by the element symbol in brackets.
nonbonding electron - electron in an atom that does not participate in a chemical bond with other atoms.
nonelectrolyte - substance that does not dissociate into ions in aqueous solution.
nonmetal - element that does not display metallic properties, typically referring to elements located in the upper right corner of the periodic table.
nonpolar bond - chemical bond with even distribution of charge such that it does not have positive or negative poles.
nonpolar molecule - molecule that has even distribution of charge such that it does not have positive and negative sides.
nonspontaneous reaction - chemical reaction that cannot occur without input of external work.
nonvolatile - substance that does not readily evaporate into a gas under ordinary conditions.
normal boiling point - temperature at which a liquid boils at 1 atm of pressure (sea level).
normal concentration - either refers to normal concentration in which the concentration of solutes is the same in two samples or refers to gram equivalent weight of a solute in solution (N).
normality (N) - measure of concentration equal to gram equivalent weight per liter of solution.
nuclear fission - splitting of atomic nuclei into two or more lighter nuclei, accompanied by an energy release.
nuclear radiation - particles and photons emitted during reactions in the atomic nucleus.
nucleation - process of vapor droplets condensing into a liquid, bubbles forming in a boiling liquid, or particle accretion to grow crystals.
nucleophile - atom or molecule that donates an electron pair to form a covalent bond.
nucleotide - organic molecule comprised of a nucleotide base, ribose or deoxyribose, and one or more phosphate groups.
nucleus - positively charged center of an atom, made from protons and neutrons.
nuclide - an atom or ion characterized by the proton and neutron composition of its nucleus.
null hypothesis - proposition that there is no effect of a treatment or no relationship between an independent and dependent variable.
nutraceutical - a food or part of food that confers health or medical benefits.
O - Octane Number to Oxygen
nto two or more lighter nuclei, accompanied by an energy release.
nuclear radiation - particles and photons emitted during reactions in the atomic nucleus.
nucleation - process of vapor droplets condensing into a liquid, bubbles forming in a boiling liquid, or particle accretion to grow crystals.
nucleophile - atom or molecule that donates an electron pair to form a covalent bond.
nucleotide - organic molecule comprised of a nucleotide base, ribose or deoxyribose, and one or more phosphate groups.
nucleus - positively charged center of an atom, made from protons and neutrons.
nuclide - an atom or ion characterized by the proton and neutron composition of its nucleus.
null hypothesis - proposition that there is no effect of a treatment or no relationship between an independent and dependent variable.
nutraceutical - a food or part of food that confers health or medical benefits.
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O - Octane Number to Oxygen
octane number - value that indicates resistance of motor fuel to engine knock relative to the knock from isooctane (100) and heptane (0).
octet - group of 8 valence electrons around an atom.
octet rule - principal that atoms in an atomic bond share their 8 outer electrons.
open system - a system able to freely exchange matter and energy with its surroundings.
orbital - mathematical function that describes the wavelike behavior of an electron.
organic chemistry - study of the chemistry of compounds containing carbon chemical bonded to hydrogen.
osmium - Osmium is the name for the element with atomic number 76 and is represented by the symbol Os. It is a member of the transition metal group.
osmosis - movement of solvent molecules across a semipermeable membrane from a dilute solution to a more concentrated solution, thus diluting it and equalizing concentration on both sides of the membrane.
oxidant - a reactant that oxidizes or removes electrons from another reactant in a redox reaction.
oxidation - loss of electrons by an atom, molecule or ion in a chemical reaction.
oxidation number - the electrical charge of a central atom in a coordination compound if all electron pairs and ligands were removed.
oxidation state - the difference between the number of electrons in an atom in a compound compared with the number of electrons in a neutral atom of the element.
oxide - an ion of oxygen with an oxidation state equal to 2- (e.g., iron oxide).
oxidizer - a reactant that removes electrons from another reactant in a redox reaction.
oxidizing agent - an oxidizer; a reactant that removes electrons from another reactant.
oxyanion - an anion that contains the element oxygen.
oxygen - Oxygen is the name for the element with atomic number 8 and is represented by the symbol O. It is a member of the nonmetal group.
P - Palladium to Pure Substance
palladium - transition metal with element symbol Pd and atomic number 46.
paramagnetism - property of material characterized by being attracted to a magnetic field.
parent atom - atom that undergoes radioactive decay, resulting in one or more daughter atoms.
parent nuclide - nuclide that decays into a specific daughter nuclide during radioactive decay.
partial pressure - the pressure a gas in a mixture of gases would exert if it occupied the volume by itself, at the same temperature.
particulate - small distinct solids suspended in a gas or liquid.
parts per million (PPM) - unit of concentration that is one part solute per one million parts solvent.
Pascal (Pa) - SI unit of pressure equal to the force of 1 Newton per square meter.
Pauli exclusion principle - principle that says no two electrons or other fermions can have identical quantum numbers in the same atom or molecule.
percent yield - percent ratio of actual yield divided by theoretical yield.
periplanar - describes two atoms or groups of atoms in the same plane as each other with respect to a single bond.
period - horizontal row of the periodic table; elements with the same highest unexcited electron energy level.
periodic law - law that states the properties of elements recur in a predictable and systematic way when they are arranged by increasing atomic number.
periodic table - tabular arrangement of elements by increasing atomic number, ordered according to trends in recurring properties.
periodic trend - regular variation in the properties of elements with increasing atomic number.
periodicity - recurring variations in element properties with increasing atomic number due to trends in atomic structure.
peroxide - a polyatomic anion with molecular formula O22-.
petroleum - crude oil; natural flammable hydrocarbon mixture found in geologic formations.
pH - measure of the hydrogen ion concentration, reflecting how acidic or basic a substance is.
phase - distinct form of matter with uniform chemical and physical properties.
phase change - change in the state of matter of a sample (e.g., liquid to vapor).
phase diagram - chart showing the phase of a substance according to temperature and pressure.
pH indicator - compound that changes color over a range of pH values.
phlogiston - Phlogiston was believed to be a substance all combustible matter contained and released when burned. Phlogiston theory was an early chemical theory to explain the process of oxidation. Phlogiston had no odor, taste, color or mass. Deflogisticated substances were called the calx of the substance.
pH meter - instrument that measure pH of a solution based on the voltage between two electrodes in the solution.
phosphorescence - luminescence produced when electromagnetic energy (usually UV light) kicks an electron from a lower to higher energy state. A photon is released when the electron falls to a lower state.
phosphorus - nonmetal with element symbol P and atomic number 15.
photon - discrete packet of electromagnetic radiation.
physical change - change that alters the form of matter but not its chemical composition.
physical property - characteristic of matter that may be observed and measured without changing the identity of the sample.
pi bond - covalent bond formed between two neighbor atom unbonded pi orbitals.
pKa - negative base 10 log of the acid dissociation constant; lower pKa correlates to stronger acid
pKb - negative base 10 log of the base dissociation constant; lower pKa correlates with stronger base.
Planck's constant - proportionality constant that relates photon energy to frequency; 6.626 x 10-34 J·sec.
plasma - state of matter with no defined shape or volume consisting of ions and electrons.
platinum - transition metal with atomic number 78 and element symbol Pt.
plutonium - Plutonium is the name for the element with atomic number 94 and is represented by the symbol Pu. It is a member of the actinide group.
quantitative analysis - determination of the amount or quantity of components in a sample.
quantum - a discrete packet of matter or energy, plural is quanta
quantum number - value used to describe the energy levels of atoms or molecules. There are four quantum numbers.
R - Radiation to Rutherfordium
radiation - emitted energy in the form of rays, waves, or particles.
radioactivity - spontaneous emission of radiation as particles or photons from a nuclear reaction.
radioactive tracer - radioactive element or compound added to a material to monitor its progress through a system.
radium - Radium is the name for the element with atomic number 88 and is represented by the symbol Ra. It is a member of the alkaline earth metals group.
radon - radioactive gas with element symbol Rn and atomic number 86.
Raoult's Law - relation that states the vapor pressure of a solution depends on the mole fraction of solute added to the solution.
reactant - starting material for a chemical reaction.
reaction - a chemical change that forms new substances.
reaction quotient - Q - ratio of the concentration of products of a reaction to the concentration of the reactants.
reaction rate - the speed at which chemical reactants form products.
reagent - compound or mixture added to a system to produce a reaction or test if one occurs.
real gas - gas that does not behave as an ideal gas because its molecules interact with one another.
redox indicator - compound that changes color at a specific potential difference.
redox reaction - set of chemical reactions involving reduction and oxidation
redox titration - titration of reducing agent by an oxidizing agent or vice versa.
reduction - half reaction in which a chemical species decreases its oxidation number, generally by gaining electrons.
refrigerant - compound that readily absorbs heat and releases it at a higher temperature and pressure.
relative density - ratio of density of a substance to the density of water.
relative error - uncertainty of a measurement compared to the size of the measurement.
relative standard deviation - measure of precision of data, calculated by dividing standard deviation by the average of data values.
relative uncertainty - relative error; uncertainty of a measurement compared to the size of the measurement.
residue- matter remaining after evaporation or distillation or an undesirable reaction byproduct or a recognizable portion of a larger molecule.
resonance - average of two or more Lewis structure, differing in the position of electrons.
reverse osmosis - filtration method that works by applying pressure on one side of a semipermeable membrane
reversible reactions - chemical reaction in which the products act as reactants for the reverse reaction.
rhenium - transition metal with atomic number 75 and element symbol Re.
rhodium - transition metal with atomic number 45 and element symbol Rh.
RNA - ribonucleic acid, a molecule which codes for amino acid sequences.
roasting - metallurgical process in which a sulfide ore is heated in air to form a free metal or metal oxide.
roentgenium - radioactive element with atomic number 111 and element symbol Rg.
room temperature - temperature that is comfortable for humans, typically around 300 K.
RT - abbreviation for room temperature; ambient temperature that is comfortable for humans.
rubidium - Rubidium is the name for the element with atomic number 37 and is represented by the symbol Rb. It is a member of the alkali metal group.
ruthenium - transition metal with atomic number 45 and element symbol Ru.
rutherfordium - radioactive transition metal with element symbol Rf and atomic number 104.
S - Salt to Synthesis Reaction
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salt - ionic compound formed by reacting an acid and a base; sometimes refers only to sodium chloride, NaCl.
salt bridge - connection containing a weak electrolyte located between the oxidation and reduction half cells of a galvanic cell.
samarium - rare earth element with atomic number 62 and element symbol Sm.
saponification - reaction between triglycerides and either sodium hydroxide or potassium hydroxide to form a fatty acid salt called soap and glycerol.
saturated - either a substance in which all atoms are linked by single bonds, a solution that contains maximum dissolved solute concentration, or a thoroughly wetted material.
saturated fat - lipid containing only single C-C bonds.
saturated solution - chemical solution containing the maximum concentration of dissolved solute for that temperature.
scandium - Scandium is the name for the element with atomic number 21 and is represented by the symbol Sc. It is a member of the transition metals group.
science - the systematic study of the nature and behavior of the world using observation and experimentation
scientific law - general rule that explains a body of observations in the form of a mathematical or verbal statement and implies a cause an effect relationship between observations.
scientific method - system of acquiring knowledge and solving problems through observation and experimental testing of hypotheses.
seaborgium - radioactive transition metal with element symbol Sg and atomic number 106.
second quantum number - ℓ, the quantum number associated with the angular momentum of an atomic electron.
selenium - nonmetal with element symbol Se and atomic number 34.
semi-metal - element with a partially filled p orbital, causing it to exhibit properties intermediate between those of metals and nonmetals.
SI - System Internationale, the standard metric system of units.
sigma bond - covalent bonds formed by overlapping of outer orbitals of adjacent atoms.
single displacement reaction - chemical reaction in which an ion of one reactant is exchanged for the corresponding ion of another reactant.
skeletal structure - two-dimensional graphic representation of atoms and bonds in a molecule using element symbols and solid lines for bonds.
sodium - Sodium is the name for the element with atomic number 11 and is represented by the symbol Na.
sol - type of colloid in which solid particles are suspended in a liquid.
solid - state of matter characterized by high degree of organization, with a stable shape and volume.
solidification - phase change that results in formation of a solid.
solubility - maximum amount of solute that may be dissolved in a specified solute.
solubility product - Ksp, the equilibrium constant for a chemical reaction in which a solid ionic compound dissolves to yield its ions in solution.
solute - substance that is dissolved in a chemical solution.
solution - homogeneous mixture of two or more substances.
solvent - component of a solution present in the greatest proportion.
specific gravity - ratio of the density of a substance to the density of water.
specific heat - quantity of heat required to raise the temperature of a mass a specified amount.
specific heat capacity - amount of heat needed to raise the temperature of a substance per unit mass.
spectator ion - ion found in the same amount on both the reactant and product sides of a chemical reaction that does not affect equilibrium.
spectroscopy - analysis of the interaction between matter and any portion of the electromagnetic spectrum.
spectrum - characteristic wavelengths of electromagnetic radiation emitted or absorbed by an object or substance.
spin quantum number (Ms) - fourth quantum number, which indicated orientation of intrinsic angular momentum of an electron in an atom.
spontaneous fission - spontaneous splitting of an atomic nucleus into two smaller nuclei and usually neutrons, accompanied by the release of energy.
spontaneous process - process which can occur without any energy input from the surroundings.
standard - reference used to calibrate measurements.
standard hydrogen electrode - SHE, the standard measurement of electrode potential for the thermodynamic scale of redox potentials.
standard oxidation potential - potential in volts generated by an oxidation half-reaction compared to the standard hydrogen electrode at 25 °C, 1 atm pressure and a concentration of 1 M.
standard reduction potential - potential in volts generated by a reduction half-reaction compared to the standard hydrogen electrode at 25 °C, 1 atm pressure and ae Shell Electron Pair Repulsion Theory
T - Tantalum to Tyndall Effect
urface of a liquid.
surfactant - species that acts as a wetting agent to lower liquid surface tension and increase spreadability.
suspension - heterogeneous mixture of solid particles in a fluid.
synthesis reaction - direct combination reaction; chemical reaction in which two or more species combine to form a more complex product.
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T - Tantalum to Tyndall Effect
Titanium is a useful transition metal. Krischan D. Rudolph / Getty Images
tantalum - transition metal with element symbol Ta and atomic number 73.
technetium - transition metal with element symbol Tc and atomic number 43.
tellurium - metalloid with element symbol Te and atomic number 52.
temperature - property of matter that is a measure of the kinetic energy of its particles; measure of heat or cold.
terbium - rare earth element with symbol Tb and atomic number 65.
tetrahedral - molecular geometry in which a central atom form four bonds directed toward the corners of a regular tetrahedron.
Texas carbon - a carbon atom that forms five covalent bonds, forming a structure resembling a star.
thallium - metal with atomic number 81 and element symbol Tl.
theoretical yield - quantity of product that would be obtained if the limiting reactant in a reaction reacted completely.
theory - a well-established explanation of scientific data which can be disproven by a single contrary result.
thermodynamics - scientific study of heat, work, and related properties of mechanical and chemical systems.
transmute - to change from one form or substance into another.
triple point - temperature and pressure at which the solid, liquid, and vapor phase of a substance coexist at equilibrium with each other.
tungsten - transition metal with atomic number 74 and element symbol W.
Tyndall effect - the scattering of a beam of light as is passes through a colloid.
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U - Ultraviolet to Uranium
Ultraviolet light is sometimes called black light because it's beyond the visible spectrum. Cultura RM Exclusive/Matt Lincoln / Getty Images
ultraviolet radiation - ionizing electromagnetic radiation with a wavelength between 100 nm and 400 nm. Sometimes called black light.
UN ID - a four-digit code used to identify dangerous or flammable chemicals. United Nations Identifier
UN number - a UN ID used for the transport of dangerous materials.
unit - a standard used for comparison in measurements.
universal gas constant - usually indicated by R, the gas constant is the Boltzmann constant in units of energy per temperature per mole: R = 8.3145 J/mol·K
universal indicator - a mixture of pH indicators used to measure pH over a wide range of values.
universal solvent - a chemical that dissolves most substances. While water is often called the universal solvent, most nonpolar molecules are insoluble in it.
unsaturated - either refers to a solution that can dissolve more solute or to an organic compound containing double or triple carbon-carbon bonds.
unsaturated fat - a lipid that contains no carbon-carbon double bonds.
unsaturated solution - a solution in which solute concentration is lower than its solubility. All solute present dissolves into the solution.
N number - a UN ID used for the transport of dangerous materials.
unit - a standard used for comparison in measurements.
universal gas constant - usually indicated by R, the gas constant is the Boltzmann constant in units of energy per temperature per mole: R = 8.3145 J/mol·K
universal indicator - a mixture of pH indicators used to measure pH over a wide range of values.
universal solvent - a chemical that dissolves most substances. While water is often called the universal solvent, most nonpolar molecules are insoluble in it.
unsaturated - either refers to a solution that can dissolve more solute or to an organic compound containing double or triple carbon-carbon bonds.
unsaturated fat - a lipid that contains no carbon-carbon double bonds.
unsaturated solution - a solution in which solute concentration is lower than its solubility. All solute present dissolves into the solution.
Volumetric flasks are used to prepare chemical solutions. COLIN CUTHBERT/SCIENCE PHOTO LIBRARY / Getty Images
vacuum - a volume containing little to no matter (no pressure).
valence - number of electrons needed to fill the outermost electron shell.
valence bond theory - explanation of bonding between two atoms as a result of the overlap of half-filled atomic orbitals.
valence electron - outer electron most likely to participate in bond formation or a chemical reaction.
Valence Shell Electron Pair Repulsion Theory - molecular model that predicts geometry of atoms in a molecule by minimizing electrostatic forces between valence electrons around a central atom.
vanadium - Vanadium is the name for the element with atomic number 23 and is represented by the symbol V. It is a member of the transition metals group.
vapor pressure - pressure exerted by a vapor in equilibrium with liquid or solid phases of the same substance or the partial pressure of a vapor above its liquid or solid.
vaporization - phase transition from the liquid phase to gas phase.
vector - a geometric object that has both magnitude and direction.
viscosity - how readily a fluid flows, which is the ratio between an applied shear stress and the resulting velocity gradient.
visible light - electromagnetic radiation that can be perceived by the human eye, usually from 380 nm to 750 nm (400 to 700 nm).
water of hydration - water stoichiometrically bound in a compound, forming a hydrate.
wavefunction - a function that describes the probability of the quantum state of a particle in terms of spin, time, position, and/or momentum.
wavelength - the distance between identical points of two successive waves.
wave-particle duality - the concept that photons and subatomic particles exhibit properties of both waves and particles.
wax - a lipid consisting of chains of esters or alkanes derived from fatty acids and alcohols.
weak acid - an acid that only partially dissociates into its ions in water.
weak base - a base that only partially dissociates in water.
weak electrolyte - an electrolyte that does not completely dissociate into its ions in water.
wedge-and-dash projection - molecule representation using three types of lines to show three-dimensional structure.
weight - the force on a mass due to the acceleration of gravity (mass multiplied by acceleration).
word equation - a chemical equation expressed in words rather than chemical formulas.
work - force multiplied by distance or the amount of energy needed to move a mass against a force.
working solution - a chemical solution prepared for use in a lab, usually by diluting a stock solution.
X - Xenon to X-Rays
xenon - Xenon is an element with an atomic number of 54 and atomic weight of 131.29. It is an odorless inert gas that is used to fill cathode ray tubes.
x-rays - X-rays are light rays with a wavelength from 0.01 to 1.0 nanometers. Also Known As: X radiation
Y - Yield to Yttrium
yield - In chemistry, yield refers to the quantity of a product obtained from a chemical reaction. Chemists refer to experimental yield, actual yield, theoretical yield, and percent yield to differentiate between calculated yield values and those actually obtained from a reaction.
ytterbium - Ytterbium is element number 70 with an element symbol Yb.
yttrium - Yttrium is an element element with an atomic number of 39 and atomic weight of 88.90585. It is a dark gray metal that is used to make alloys for nuclear technology because the element has a high neutron transparency
Z - Zaitsev Rule to Zwitterion
Zaitsev rule - rule in organic chemistry that states alkene formation from an elimination reaction will produce more highly substituted alkenes.
zinc - Zinc is the name for the element with atomic number 30 and is represented by the symbol Zn. It is a member of the transition metals group.
zirconium - Zirconium is the name for the element with atomic number 40 and is represented by the symbol Zr. It is a member of the transition metals group.
zwitterion - the dipolar amino acid formed when a hydrogen ion transfers from an acid group to an amine group.
In 1903 Rutherford announced that radioactivity is caused by the breakdown of atoms.
In 1945 Glenn Seaborg identified lanthanides and actinides (atomic number >92), which are usually placed below the periodic table.
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