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Chemistry
Regents Chemistry
Term | Definition |
---|---|
Acidity | a measure of the hydrogen (hydronium) ion concentration of a solution |
activated complex | the temporary, intermediate product in a chemical reaction |
activation energy | the amount of energy needed to form an activated complex from reactants |
addition polymerization | joining of monomers of unsaturated compounds |
addition reaction | an organic reaction in which a substance such as hydrogen or a halogen is added to the site of a double or triple bond |
alcohol | a organic compound containing the hydroxyl group (-OH) as the functional group |
aldehyde | an organic compound in which the carbonyl group (-C=O) is at the end of a carbon chain |
alkali metal | an element of group 1 |
alkaline earth metal | an element of group 2 |
alkalinity | a measure of the hydroxide ion concentration of a solution |
alkane | one of the homologous series of saturated hydrocarbons |
alkyl group | a group that contains one less hydrogen atom than an alkane with the same number of carbon atoms |
alkene | one of the homologous series of hydrocarbons that contain one triple covalent bond |
alkyne | one of the homologous series of hydrocarbons that contain one triple covalent bond |
allotrope | one of two or more different forms of an element in the same phase |
alloy | a homogeneous mixture of a metal with another element, usually another metal |
alpha particle | a helium nucleus |
amide | the product obtained form the reaction of an organic acid with an amine |
amine | an ammonia derivative in which one or more of the hydrogen atoms are replaced by an alkyl group |
amino acid | an organic compound containing both the amine group (-NH2) and the carboxylic group (-COOH) |
analysis | a chemical reaction in which a compound is broken down (decomposed) into simpler substances |
anode | the site in an electrochemical cell where oxidation occurs |
Arrhenius acid | a substance that produces hydronium ions (H3O+) as the only positive ions when dissolved in water. |
Arrhenius acid | a substance that produces hydronium ions (OH-) as only negative ions when dissolved in water |
artificial transmutation | a transmutation caused by bombarding a nucleus with a high-energy particle, such as a neutron or an alpha particle |
asymmetrical molecule | a molecule that lacks identical atomic structure on each side of an axis |
atom | the smallest particle of an element that can enter into a chemical reaction |
atomic mass | the average mass of all the isotopes in a sample of an element |
atomic mass unit | one-twelfth the mass of a carbon-12 atom` |
atomic number | the number of protons in the nucleus of an atom |
atomic radius | half the distance between two adjacent atoms in a crystal or half the distance between nuclei of identical atoms bonded together |
Avogardo's number | the number of representative particles contained in on mole of a substance; equal to 6.02x10^23 particles |
beta particles | high-energy electrons whose source is an atomic nucleus |
boiling point | the temperature at which the vapor pressure of a liquid is equal to the atmospheric pressute |
catalyst | a substance that alters the speed of a chemical reaction without being permanently changed |
cathode | the site in an electrochemical cell where reduction occurs |
chemical change | a reaction in which the composition of a substance is changed |
chemistry | the study of the composition of matter and changes that occur in it |
coefficient | the number placed before a formula indicating the number of units of that substance |
collision theory | for a chemical reaction to occur, reactant particles must collide |
combustion | an exothermic reaction with oxygen, releasing heat |
compund | a substance composed of two or more elements that are chemically combined in definite proportions by mass |
condensation | an exothermic process in which a vapor or a gas changes into the liquid phase; the potential energy of the substances decreases during this constant temperature process; the reverse of the vaporization process |
condensation polymerization | the bonding of monomers by removing water from hydroxyl groups and joining the monomers by an ether or ester linkage |
conductivity | a measure of the ability of an electric current to flow through a substance |
conjugate acid-base pair | a pair of chemical formulas that differ only by the presence of a hydrogen ion |
covalent bond | a bond formed by the sharing electrons between two nuclei |
decomposition | a chemical reaction in which a compound is broken down into simpler substances |
deposition | the process in which a gas changes directly into a solid; the reverse of sublimation |
diatomic molecule | a molecule containing two identical atoms |
double covalent bond | the sharing of two pairs of electrons between two nuclei |
double replacement | a chemical reaction in which ions exchange places |
ductility | property of a metal that enables it to be drawn into a wire |
electrochemical cell | a system in which there is an electric current flowing while a chemical reaction occurs |
electrode | the site at which oxidation or reduction occurs; an anode or cathode |
electrolysis | a process in which an electric current forces a non-spontaneous redox reaction to occur |
electrolyte | a substance whose water solution conducts an electric current |
electrolytic cell | a cell that requires electricity to cause a non-spontaneous redox reaction to occur |
electron | a fundamental particle of matter having a negative charge |
electron configuration | the distribution of the electrons in an atom |
electronegativity | a measure of the attraction of the nucleus for a bonded electron |
element | substances that cannot be broken down or decomposed into simpler substances by chemical means |
empirical formula | the simplest integer ratio in which atoms combine to form a compound |
endothermic | a chemical reaction that absorbs heat, producing products with more potential energy than reactants |
entropy | a measure of the disorder or randomness of a system |
equilibrium | a condition in which the rates of opposing reactions are equal |
equilibrium expression | a mathematical expression that shows the relationship of reactants and products of a system at equilibrium |
ester | the organic product of an esterification reaction containing -COOC- as the functional group |
esterification | a chemical reaction between an alcohol and an acid to produce an ester and water |
ether | an organic compound in which oxygen is bonded to two carbon atoms (R1-O-R2) |
evaporation | the process by which molecules in the liquid phase escape into gaseous phase |
excited state | the condition that exists when the electrons of an atom occupy higher energy levels while lowers levels are vacant |
exthermic | a chemical reaction that releases heat, producing products with less potential energy that the reactants |
family | a vertical colomn on the periodic table |
fermentation | an organic reaction in which ethanol and carbon dioxide are produced from a carbohydrate |
fission | splitting of large nuclei into middle-weight nuclei and neutrons |
formula point | the sum of atomic masses of all atoms present |
freezing point | the temperature at which both solid and liquid phases of a substance exist in equilibrium; the same temperature as th substance's melting point |
freezing | the constant temperature process in which particles in the liquid phase lose energy and change into solid phase; also known as solidification; the reverse of the melting phase |
functional group | the atoms or atoms that replaces a hydrogen in the hydrocarbon and give a class of organic compounds characteristics properties |
fusion | the constant temperature process in which particles in the solid phase gain enough energy to break away into the liquid phase; also known as melting; the reverse of the freezing process |
gamma ray | high-energy ray similar th an X-ray |
gaseous phase | a phase of matter without definite shape or volume |
gram formula mass | the formula mass expressed in grams instead of atomic mass units |
ground state | the condition of an atom or ion in which the electrons occupy the lowest available energy levels |
group | a verticle column on the periodic table |
half-life | the length of time for the half of a given sample of a radioisotope to decay |
half-reaction | a reaction that shows either the oxidation or reduction portion of a redox reaction |
halide | a salt that includes a halogen |
halogen | an element of Group 17 |
heat | energy transferred from one substance to another; measured in units of calories or joules |
heat of fusion | the amount of heat needed to convert a unit mass of a substance from a liquid to a vapor at its boiling point |
heterogeneous | a mixture in which the particles are not uniformly mixed |
homogeneous | a substance in which the particles are uniformly mixed |
homologous series | a group of related compounds in which each member differs from the one before it by the same additional unit |
hydrate | the crystalline form of an ionic substance that contains a definite number of water molecules |
hydrocarbon | organic compound containing only hydrogen and carbon atoms |
hydrogen bond | the attraction of a hydrogen atom in one molecule for an oxygen, nitrogen, or fluorine atom in another molecule |
hydrogen ion | a hydrogen atom without its electron (consisiting solely of a proton) |
hydronium ion | H3O+, formed by the combination of water with a hydrogen ion |
hydroxide ion | the polyatomic anion produced by the ionization of a water molecule |
hydroxyl group | the group comprised of an oxygen atom and a hydrogen atom (-OH) responsible for the properties of alcohols |
indicator | a substance that undergoes a color change that can be used to determine when a reaction is complete |
inert gas group | former name of the Group 18 noble gases |
insoluble | material with a low solubility |
ionic bond | a bond formed by the transfer of electrons from one atom to another |
ionic radius | the distance from the nucleus to the outer energy level of the ion |
ionization energy | the amount of energy needed to remove the most loosely bound electron from a neutral gaseous atom |
isomers | compounds with the same molecular formula but different structural arrangement |
isotope | atom of an element that has a specific number of protons and neutrons |
ketone | an organic compound in which the carbonyl group (-C=O) is joined to two other carbon atoms |
kinetic molecular theory | a theory used to explain the behavior of gases in terms of the motion of their particles |
law of conservation of mass | matter is neither created nor destroyed in chemcial reactions |
law of definite proportions | types of atoms in a compound exist in a fixed ration |
Le Châtelier's principle | a system at equilibrium will react to reduce a stress |
Lewis dot diagram | a diagram the depicts valence electrons as dots around the atomic symbol (representing the nucleus and nonvalence electrons) of the element |
liquid phase | a phase of matter having definite volume but no definite shape (takes the shape of its container) |
malleability | the property of metals that allows them to be hammered into shapes |
mass number | the total number of protons and neutrons in the nucleus of an atom |
matter | anything that has mass and volume |
melting point | the temperature at which both the solid and liquid phases exist in equilibrium; the same temperature as the substance's freezing point |
metal | element whose atoms lose electrons in chemical reactions to become positive ions |
metallic bond | the attraction of valence electrons for the positive kernels of matellic atoms |
metalloid | an element that has both metallic and nonmetallic properties |
molarity | the concentration of a substance in moles per liter of solution |
mole | the number of atoms of carbon present in 12.000g of carbon-12 |
molecular formula | the actual ratio of the atoms in a molecule |
molecule | the smallest unit of a covalently bonded substance that has the properties of that substance |
monomer | each individual unit of a polymer |
multiple covalent bond | a double or triple covalent bond |
neutralization | the reaction between an acid and a base to produce water and a salt |
neutron | the unchanged particle in the nucleus of an atom |
noble gas | a nonreactive element that is in Group 18 on the periodic table |
nonmetal | element whose atoms will gain or share electrons in chemical reactions |
nonpolar covalent bond | a bond formed by the equal sharing of a pair of electrons between two nuclei |
nucleus | the dense, positively charged central core of an atom |
octet of electrons | the stable valence electron configuration of eight electrons |
orbital | a region in an atom in which an element of a particular amount of energy is most likely to be located |
organic acid | an organic compound containing one or more carboxyl group (-COOH) |
organic halide | an organic compound in which one or more hydrogen atoms have been replaced by an atom of a halogen; also known as as a halocarbon |
oxidation number (state) | number assigned to keep track of electron gain or loss in redox reactions |
oxidation | the loss of electrons and an increase in oxidation state |
oxidizing agent | the substance reduced in a redox reaction |
parts per million | the ratio between the parts of solute per million parts of solution |
percent by volume | the concentration of a solution expressed as the ratio between the volume of the solute and total volume of the solution, expressed as a percent |
percent mass | the concentration of a solution expressed as the ratio between the mass of the solute and the total mass of the solution, expressed as a percent |
percentage composition | the composition of a compound as a percentage of each element compared with the total mass of the compound |
period | a horizontal row of the periodic table |
periodic law | the properties of elements are periodic functions of their atomic numbers |
pH scale | a logarithmic scale that emasures the acidity or alkalinity of a solution on a scare of 1-14 |
pH | the negative logarithm of a solution's hydrogen ion concentration |
physical change | a change that does not alter the chemical properties of a substance |
polar covalent bond | a bond formed by the unequal sharing of electrons between two nuclei |
polyatomic ion | a covalently bonded group of atoms that have a net electric charge |
polymer | organic compound made up of chains of smaller units bonded together |
polymerization | an organic reaction in which many small units are joined together to form a long chain |
positron | a particle identical to an electron except that it has a positive charge |
potential energy diagram | a diagram showing the changes in potential energy as a reaction proceeds |
primary alcohol | an alcohol with a hydroxyl group attached to a carbon atom at the end of a chain |
product | a substance formed in a chemical reaction, shown to the right of the arrow in an equation |
proton | the positivly charged particle in the nuclus of an atom |
pure substance | a compound or an element; a material in which the composition is the same throughout |
qualitative | information that cannot be counted or measured |
quantitative | information that can be either counted or measured |
quantum number | on of a set of four numbers that describes a property of an electron in an atom |
quantum theory | a concept that relates the chemical behavior of atoms to energy being transfered in discrete units called quanta |
radioisotope | an unstable nucleus that is radioactive |
reactant | a starting substance in a reaction, shown to the left of the arrow in an equation |
redox | an oxidation-reduction reaction |
reducing agent | the substance oxidized in a redox reaction |
reduction | the gain of electrons and the loss of oxidation number |
salt | the product (other than water) of a neutralization reaction; an ionic substance consisting of a metalication and anion other than the hydroxide ion |
salt bridge | a part of a voltaic cell that connects two containers and allows the flow of ions |
saponification | the reaction of an alkali and a fat to produce glycerol and a soap |
saturated | (solution) a solution containing the maximum amount of solute that will dissolve at a given temperature; (Organic) organic compounds containing only single covalent bonds |
secondary alcohol | an alcohol with a hydroxyl group attached to a carbon atom that is attached to two other carbon atoms |
single covalent bond | only one pair of electrons is shared between two atoms |
single replacement | a reaction in which an elment replaces a less reactive element in a compound |
solid phase | a phase of matter having a definite shape and volume; particles in this phase have a definite crystalline arrangement |
salubility | a measure of how much solute will dissolve in a certain amount of solvent at a specific temperature |
soluble | material with high salubility |
solute | the substance being dissolved |
solution | a homogeneous mixture of substances in the same physical state |
solvent | the substance that dissolves the solute |
stress | any changein concentration, pressure, or temperature on an equilibrium system |
sublimation | the process in which a solid changes directly inot a gas; the reverse of deposition |
subscript | the number written after a chemical symbol in a formula indicating the number of atoms present |
substitution reaction | one or more hydrogen atoms is removed from a saturated hydrocarbo and replaced by another |
supersaturated | a solution tha contains more solute than ould dissolve in a saturated solution at a given temperature |
symbol | a one-, two- or three-letter designation of an element |
symmetric molecule | a molecule with identical atomic structure on each side of an axis |
synthesis | a reaction in which two or more substances combine to form one product |
temperature | the measure of the average kinetic energy of a substance's particles |
tertiary alcohol | an alcohol with a hydroxyl group attached to a carbon atom that is attached to thress other carbon atoms |
titration | the process of determining the concentration of an unkown solution by a reaction with a solution of known concentration |
tracer | a radioisotope used to track a chemical reation |
transmutation | the changing of a nucleus of one element into that of a different element |
triple bond | the sharing of three pairs of electrons between two nuclei |
unstaturated | (solution) a solution in which more solute can be dissolved at a given temperature; (organic) an organic compound containing one or more double or triple covalent bonds |
valence electrons | the electrons in the outer energy level of an atom |
vapor | the gaseous state of a substance that is normally a liquid at room temperature |
vapor pressure | the pressure that a vapor exerts |
vaporization | the constant temperature process in which particles in the liquid phase gain enough energy to break away from the gaseous phase; also known as boiling; the reverse of the condensaiion process |
voltaic cell | an electrochemical cell in which a spontaneous chemical reaction causes a flow of electrons |
wave-mechanical model | the current model of the atom that deals with the wave-particle duality of nature |