Regents Chemistry Vocabulary – Flashcards
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| Activation Energy |
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| Energy required to start a chemical reaction. Can be determined by looking at a potential energy diagram (difference between the reactants and the highest point on the diagram). |
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| Allotrope. |
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| Different molecular forms of the same element with different properties (due to different structures); examples: graphite and diamond (both carbon allotropes); oxygen and ozone (both oxygen allotropes) |
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| Alternate A/B Theory (Bronsted-Lowry Theory) |
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| Acids donate H+ (protons), bases accept H+ (protons). (BAAD) |
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| Arrhenius Acid |
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| a substance that dissolves in water to yield H+ (H3O+ or hydronium) ions. |
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| Arrhenius Base: |
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| a substance that dissolves in water to yield OH- (hydroxide) ions. |
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| Artificial Transmutation |
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| Nuclear reaction in which a nuclide is shot with another particle to produce a different element |
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| Avogadro’s Hypothesis |
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| Equal Pressure, Volume & Temperature of different gases indicates that there are equal number of molecules (assuming ideal gas behavior). |
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| Cathode |
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| The electrode where reduction occurs; due to the reduction of the cations in solution at the cathode, its mass will always increase. (AN OX, FAT RED CAT) |
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| Chemical Property |
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| A property that changes the identity of the substance (i.e. flammability, rusting) |
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| Combustion |
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| An organic compound, typically a hydrocarbon, reacts with O2 to form CO2 + H2O; always exothermic |
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| Compound |
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| Substance that can be chemically decomposed into two or more elements; its name will not appear on Reference Table S. |
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| Conductivity |
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| Ability to transfer electrical charge from one place to another; due to substance having freely moving charged particles (ions in aqueous solution; electrons in metallic substance) |
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| Covalent Bond |
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| Bond formed when two nonmetal atoms share valence e-. |
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| Decomposition |
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| Breaking a compound down into two or more substances |
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| Diatomic Molecule |
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| Molecule made of two atoms of the same element (HOFBrINCl) |
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| Distillation |
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| Separation of two substances based on differences in boiling point. |
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| Electrolyte |
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| A substance that ionizes in water and conducts electricity. |
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| Electronegativity |
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| An atom’s attraction to electrons in a chemical bond. |
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| Element |
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| Substance that cannot be decomposed by chemical change. |
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| Empirical Formula |
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| Simplest whole- number mole ratio of elements in compound |
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| Entropy |
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| The state of randomness or disorder in the particles of a system. |
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| Equilibrium |
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| A condition where the rate of forward and reverse reactions are equal; this is observed when the concentrations or pressures of the reactants and products no longer appear to be changing. |
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| Excited State |
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| Where electrons are in higher PELs than they would normally be; the electrons have to absorb energy in order to go to the excited state. |
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| Exothermic |
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| A change that results in an overall decrease in potential energy (by transferring energy out of the system – heat flows out). Endothermic reactions result in an overall increase in potential energy (by transferring energy into the system – heat flows in). |
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| Fermentation |
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| Yeast enzyme zymase converts sugar into ethanol and carbon dioxide. |
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| Gram-Formula Mass |
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| The sum of the contribution of atomic masses from each element found in a substance. |
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| Half-Life |
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| The period of time for a radioactive substance to lose half of its radioactivity (i.e. only half of the original radioisotope is present after each successive half-life). |
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| Heat of Fusion |
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| The amount of energy needed to melt 1 g of substance at its melting point. |
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| Heat of Reaction |
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| The total amount of chemical potential energy lost or gained during a change (DH); can be determined by using Reference Table I for many reactions. |
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| Hydrogen Bonds |
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| The strongest type of IMF; found between the hydrogen of one molecule and the F, O or N found on an adjacent molecule. |
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| Ideal Gas |
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| One where the molecules are as small and far apart as possible so as to minimize the possible formation of IMF between adjacent molecules. Ideal gas conditions are best met when the gas sample is kept under low pressures and high temperatures (PLIGHT). |
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| Intermolecular Forces of Attraction |
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| Attractions between adjacent molecules (i.e. the attraction between two adjacent water molecules in a sample of water). A bond holds together atoms inside ONE molecule. |
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| Ionic Bond |
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| A type of chemical bond formed when a metal atom transfers a valence electron to a nonmetal atom; the metal ion assumes a positive charge and the nonmetal assumes a negative charge. |
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| Ionization Energy |
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| The energy required to remove the most loosely bound valence electron in an atom. |
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| Isomer |
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| A compound that contains the same molecular formula but a different structural formula |
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| Isotopes |
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| Atoms of the same element (same number of protons) with different numbers of neutrons; the result would be the two isotopes having different mass numbers. |
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| Law of Conservation Of Mass |
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| Mass cannot be created or destroyed during any reaction. |
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| Mass Number |
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| The total number of protons plus neutrons in the nucleus; the electrons are considered to have negligible mass and therefore do not contribute to the overall mass of the atom. |
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| Molarity |
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| A measure of concentration of a solution; moles of solute dissolved per liter of solution (Reference Table T). |
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| Molecular Formula |
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| Actual number of atoms of each element in molecule |
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| Molecule-Ion Attraction |
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| Attraction for polar solvent molecules to ions in solution; causes some ionic compounds to dissolve in water (Reference Table F) |
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| Monatomic |
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| Atoms of noble gas that have a stable octet without having to bond. |
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| Natural Decay |
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| An unstable nucleus emits radiation to become more stable; this is a spontaneous process determined by the half-life of the element and the neutron to proton ratio found in the nucleus. |
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| Network Solids |
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| Crystal lattice of covalently bonded nonmetal or metalloid atoms (i.e. C or Si) |
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| Neutralization |
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| An acid reacts with a base to form a salt and water. |
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| Nuclear Charge |
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| The positive charge of the nucleus due to the number of protons. |
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| Nuclear Fission |
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| A large nucleus is split into two smaller nuclei (i.e. uranium bombarded with neutron) |
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| Nuclear Fusion |
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| Two small nuclei combine to make one larger nucleus (i.e. formation of helium from two hydrogen atoms) |
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| Orbital |
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| Location around a nucleus where an electron is most likely to be found; tied to the wave-mechanical model (modern model) of the atom. |
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| Oxidation Number |
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| Charge of an atom or ion |
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| Oxidation |
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| The loss of electrons (OIL RIG) |
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| Percent Composition |
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| Ratio of part to whole multiplied by 100 to make the fraction into a percentage (Reference Table T). |
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| Petroleum (crude oil) |
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| A mixture of hydrocarbons refined through fractional distillation into its component fuels. |
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| pH |
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| Measure of the relative acidity of a solution; –log [H3O+] ions in solution, each pH change of 1 is a 10-fold change in strength |
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| Polar Covalent Bond |
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| Sharing electrons unevenly due to a difference in electronegativity values between the two nonmetal elements comprising the chemical bond. |
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| Polar Molecule: |
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| Molecule which contains an asymmetric distribution of charge (SNAP) |
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| Potential Energy |
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| Energy stored in the chemical bonds of substances. |
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| Redox Reaction |
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| A reaction where one or more elements changes charge; the simultaneous loss (oxidation) and gain (reduction) of electrons in a chemical reaction. |
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| Salt Bridge |
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| Completes the circuit and allows for migration of ions in a voltaic (galvanic) cell. |
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| Saponification |
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| Fats react with bases to form soap and glycerol. |
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| Saturated |
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| A solution with the maximum quantity of solute dissolved at a given temperature. A saturated solution is an example of an equilibrium system in which the rate of dissolving equals the rate of crystallization. |
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| Solution |
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| Homogeneous mixture made of solute dissolved into a solvent. |
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| Spontaneous |
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| A reaction which, once started, goes all the way to completion without outside interference. |
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| Sublimation |
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| Phase change from a solid to a gas. |
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| Temperature |
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| The average kinetic energy of the molecules in a system. |
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| Transition Metal |
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| Elements in groups 3-12 that form colored solutions. |
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| Valence Electrons |
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| Electrons in the outermost principal energy level. |
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| Voltaic Cell |
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| Uses a spontaneous redox reaction to convert stored chemical potential energy into electrical energy (makes an electrical current). |
