General Chemistry – Flashcards
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| matter |
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| anything that has mass and occupies space |
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| energy |
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| the capacity to do work or to transfer heat |
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| kinetic energy |
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| the energy of motion |
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| potential energy |
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| energy an object possesses because of its position, condition, or composition |
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| exothermic process |
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| a process that releases energy (heat) into the environment |
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| endothermic process |
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| a process that absorbs energy (heat) from the environment |
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| Law of Conservation of Matter |
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| there is no observable change in the quantity of matter during a chemical reaction or during a physical change |
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| scientific (natural) law |
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| a general statement based on the observed behavior of matter to which no exceptions are known |
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| Law of Conservation of Energy |
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| energy cannot be created or destroyed in a chemical reaction or in a physical change. It can only be converted from one form to another. |
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| Law of Conservation of Energy and Matter |
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| the combined amount of matter and energy in the universe is fixed (related to Newton's 2nd Law E=mc^2) |
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| solid |
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| a state of matter in which substances are rigid and have definite shapes; very difficult to compress |
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| liquid |
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| a state of mater in which substances flow and assume the shape of containers up to the volume of the liquid; difficult to compress |
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| gas |
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| a state of matter in which substances occupy all parts of containers; easily compressed and expanded |
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| chemical properties |
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| characteristics of matter as it undergoes chemical changes; e.g., the rxn that occurs when metallic magnesium combines with gaseous oxygen |
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| physical properties |
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| characteristics of matter with no changes in chemical composition; e.g., color, hardness, density, melting point, etc. |
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| extensive properties |
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| properties that depend on the amount of material present in the sample; e.g., volume and mass |
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| intensive properties |
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| properties that are independent of the amount of material present in the sample; all chemical properties are intensive |
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| chemical change |
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| a reaction in which 1) one or more substances are used up (at least partially), 2) one or new substances are formed, and 3) energy is absorbed or released |
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| physical change |
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| a change in which a substance changes from one physical state to another, but no substances with different compositions are formed; energy is absorbed or released |
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| mixture |
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| a combination of two or more pure substances in which each substance retains its own composition and properties |
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| heterogeneous mixture |
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| a mixture that does not have uniform composition and properties throughout |
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| homogeneous mixture/solution |
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| a mixture that has uniform composition and properties throughout |
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| Classification of Matter |
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| [image] |
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| characteristics of any mixture |
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| 1) the composition can be varied and 2) each component of the mixture retains its own properties |
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| substance |
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| any kind of matter, all specimens of which have the same chemical composition and physical properties |
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| compound |
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| a substance that can be decomposed by chemical means into simpler substances, always in the same ratio by mass |
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| element |
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| a substance that cannot be decomposed into simpler substances by chemical changes |
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| Law of Definite Proportions (aka Law of Constant Composition) |
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| different samples of any pure compound contain the same elements in the same proportions by mass; this corresponds to atoms of these elements in fixed numerical ratios |
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| mass |
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| the measure of the quantity of matter a body contains |
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| weight |
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| a measure of the gravitational attraction of a body to Earth (or other such object) |
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| primary SI units of measurement: mass, length, volume |
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| kilogram, meter, cubic meter |
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| accuracy |
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| how closely a measured value agrees with the correct value |
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| precision |
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| how closely individual measurements agree with one another |
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| dimensional analysis |
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| calculation based problem solving |
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| unit factor method |
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| a technique used to perform unit conversions |
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| density |
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| mass per unit volume; D = m/V |
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| specific gravity |
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| the ratio of the density of a substance to the density of water, both at the same temperature |
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| density of water |
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| 1.000 g/mL at 3.98˚C |
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| temperature |
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| measures the intensity of heat of a body |
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| heat |
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| a form of energy; always flows spontaneously from a hotter body to a colder body (never reverse) |
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| Kelvin (K) |
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| the basic unit of temperature in the SI system |
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| joule (J) |
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| the SI unit of energy and work; defined as 1 kg·m2/s2 |
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| calorie |
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| a unit of heat energy defined as 4.184J; originally defined as the amount of heat required to raise the temperature of one gram of water from 14.5˚C to 15.5˚C |
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| specific heat |
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| the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius (or kelvin) with no change in phase |
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| heat capacity |
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| the amount of heat required to raise the temperature of a body 1˚C. |
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| temperature scale conversions |
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| ˚F = 1.8˚C+32˚; ˚C = (˚F - 32˚)/1.8; K = ˚C+273 |
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| allotropic modifications (allotropes) |
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| different forms of the same element in the same physical state |
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| anhydrous |
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| without water |
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| anion |
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| an ion with a negative charge |
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| atom |
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| the smallest particle of an element that maintains its chemical identity through all chemical and physical changes |
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| atomic mass unit (amu) |
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| one twelfth of the mass of an atom of the carbon-12 isotope; a unit used for stating atomic formula weights |
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| atomic number |
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| the number of protons in the nucleus of an atom |
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| atomic weight |
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| weighted average of the masses of the constituent isotopes of an element; the relative mass of atoms of different elements |
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| Avogadro's number |
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| 6.022 x 1023 units of a specified item |
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| Cation |
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| ion with a positive charge |
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| chemical formula |
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| combination of symbols that indicates the chemical composition of a substance |
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| composition stoichiometery |
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| describes the quantitative (mass) relationships among elements in compounds |
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| empirical formula/simplest formula |
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| the smallest whole-number ratio of atoms present in a compound |
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| formula unit |
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| the smallest repeating unit of a substance - for non-ionic substances, the molecule |
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| formula weight |
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| the mass, in atomic mass units, of one formula unit of a substance. Numerically equal to the mass, in grams, of one mole of the substance. This number is obtained by adding the atomic weights of the atoms specified in the formula |
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| hydrate |
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| a crystalline sample that contains water and another compound in a fixed mole ratio. Examples include: CuSO4 * 5H2O and (COOH)2 * 2H2O |
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| ion |
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| an atom or group of atoms that carries an electric charge (cations and anions) |
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| ionic compound |
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| a compoun that is composed of cations and anions; example: sodium cloride, NaCl |
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| Law of Multiple Proportions |
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| when two elements, A and B, form more than one compound, the ratio of the masses of element B that combine with a given mass of element A in each of the compounds can be expressed by small whole numbers |
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| molar mass |
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| the mass of a substance in one mole of the substance; numerically equally to the formula weight of the substance |
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| mole |
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| 6.022 x 1023 (Avogadro's number of) formula units (or molecules, for a molecular substance) of the substance under discussion; the mass of one mole, in grams, is numerically equal to the formula (molecular) weight of the substance |
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| molecular fomula |
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| a formula that indicates the actual number of atoms present in a molecule of a molecular substance |
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| molecular weight |
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| the mass, in atomic mass units, of one molecule of a nonionic (molecular) substance. Numerically equal to the mass, in grams, of one mole of such a substance; this number is obtained by adding the atomic weights of the atoms specified in the formula |
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| molecule |
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| the smallest particle of an element or a compound that can have a stable independent existence |
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| percent composition |
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| the mass percentage of each element in a compound |
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| percent purity |
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| the mass percentage of each element in a compound |
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| polyatomic |
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| consisting of more than one atom; element examples: Cl2, P4, and S8; ion examples: ammonium ion, NH4+, and sulfate ion, SO42- |
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| stoichiometry |
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| description of the quantitative relationships among elements in compounds (composition stoichiometry) and among substances as they undergo chemical changes (reaction stoichiometry) |
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| structural formula |
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| a representation that shows how atoms are connected in a compound |
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| actual yield |
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| the amount of a specified pure product actually obtained from a given reaction |
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| chemical equation |
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| description of a chemical reaction by placing the formulas of reactants on the left and the formulas of products on the right of an arrow; it must be balanced - that is, it must have the same number of each kind of atom on both sides |
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| concentration |
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| the amount of solute per unit volume or mass of solvent or of solution |
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| dilution |
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| the process of reducing the concentration of a solute in a solution, usually simply by adding more solvent |
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| limiting reactant |
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| a substance that stoichiometrically limits the amount of product(s) that can be formed |
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| molarity (M) |
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| the number of moles of solute per liter of solution |
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| percent by mass |
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| 100% multiplied by the mass of a solute divided by the mass of the solution in which it is contained |
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| percent yield |
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| 100% times actual yield divided by theoretical yield |
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| products |
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| substances produced in a chemical reaction |
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| reactants |
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| substances consumed by a chemical reaction |
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| reaction ratio |
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| the relative amounts of reactants and products involved in a reaction; may be the ratio of moles, or masses |
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| reaction stoichiometry |
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| description of the quantitative relationships among substances as they participate in chemical reacions |
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| sequential reaction |
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| a chemical process in which several reaction steps are required to convert starting materials into products |
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| solute |
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| the dispersed (dissolved) phase of a solution |
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| solvent |
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| the dispersing medium of a solution |
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| theoretical yield |
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| the maximum amount of a specified product that could be obtained from specified amounts of reactants, assuming complete consumption of the limiting reactant according to only one reaction complete recovery of the product |
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| acid |
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| a substance that produces H+ (aq) ions in aqueous solution; strong acids ionize completely or almost completely in dilute aqueous solution; weak acids ionize only slightly |
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| acid-base reaction/neutralization reaction |
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| the reaction of an acid with a base to form a salt; often, the reaction of hydrogen ions with hydroxide ions to form water molecules |
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| active metal |
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| a metal that readily loses electrons to form cations |
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| activity series |
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| a listing of metals (and hydrogen) in order of decreasing activity |
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| alkali |
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| elements of Group IA in the periodic table, except hydrogen |
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| alkaline earth metals |
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| Group IIA elements in the periodic table |
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| base |
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| a substance that produces OH- (aq) ions in aqueous solution; strong bases are soluble in water and are completely dissociated; weak bases ionize only slightly |
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| binary acid |
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| a binary compound in which H is bonded to a nonmetal in Group VIIA or a nonmetal other than oxygen in Group VIA |
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| binary compound |
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| a compound consisting of two elements; may be ionic or molecular |
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| chemical periodicity |
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| the variation in properties of elements with their positions in the periodic table |
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| combination reaction |
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| reaction in which two substances (elements or compounds) combine to form one compound |
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| decomposition reaction |
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| reaction in which a compound decomposes to form two or more products (elements, compounds, or some combination of these) |
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| displacement reaction |
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| a reaction in which one element displaces another from a compound |
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| disproportionation reaction |
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| a redox reaction in which the oxidizing agent and the reducing agent are the same element |
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| dissociation |
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| in aqueous solution, the process in which a solid ionic compound separates into its ions |
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| electrolyte |
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| a substance whose aqueous solutions conduct electricity |
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| formula unit equation |
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| an equation for a chemical reaction in which all formulas are written as complete formulas |
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| gas-formation reaction |
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| a metathesis reaction in which an insoluble or slightly soluble gas is formed as a product |
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| group (family) |
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| the elements in a vertical column of the periodic table |
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| halogens |
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| Group VIIA elements in the periodic table |
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| ionization |
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| in aqueous solution, the process in which a molecular compound separates to form ions |
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| metal |
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| an element below and to the left of the stepwise division (metalloids) of the periodic table; about 80% of the known elements |
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| metalloids |
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| elements with properties intermediate between metals and nonmetals: B, Si, Ge, As, Sb, Te, Po, and At |
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| metathesis reaction |
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| a reaction in which the positive and negative ions in two compounds "change partners," with no change in oxidation numbers, to form two new compounds |
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| net ionic equation |
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| an equation that results from cancelling spectator ions from a total ionic equation |
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| noble (rare) gases |
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| elements of Group VIIIA in the periodic table |
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| nonelectrolyte |
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| a substance whose aqueous solutions do not conduct electricity |
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| nonmetals |
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| elements above and to the right of the metalloids in the periodic table |
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| oxidation |
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| an increase in oxidation number; corresponds to a loss of electrons |
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| oxidation-reduction reaction/redox reaction |
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| a reaction in which oxidation and reduction occur |
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| oxidation numbers/oxidation states |
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| arbitrary numbers that can be used as mechanical aids in writing formulas and balancing equations; for single-atom ions they correspond to the charge on the ion; less metallic atoms are assigned negative oxidation numbers in compounds and polyatomic ions |
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| oxidizing agent |
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| the substance that oxidizes another substance and is reduced |
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| period |
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| the elements in a horizontal row of the periodic table |
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| periodic law |
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| the properties of the elements are periodic functions of their atomic numbers |
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| periodic table |
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| an arrangement of elements in order of increasing atomic number that also emphasizes periodicity |
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| precipitate |
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| an insoluble solid that forms and separates from a solution |
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| precipitation reaction |
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| a reaction in which a solid (precipitate) forms |
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| pseudobinary ionic compound |
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| a compound that contains more than two elements but is named like a binary compound |
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| reducing agent |
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| the substance that reduces another substance and is oxidized |
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| reduction |
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| a decrease in oxidation number; corresponds to a gain in electrons |
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| reversible reaction |
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| a reaction that occurs in both directions; described with double arrows |
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| salt |
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| a compound that contains a cation other that H+ and an anion other than OH- or O2- |
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| semiconductor |
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| a substance that does not conduct electricity at low temperatures but does so at higher temperatures |
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| spectator ions |
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| ions in solution that do not participate in a chemical reaction; they do not appear in net ionic equations |
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| strong acid |
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| an acid that ionizes (separates into ions) completely, or very nearly completely, in dilute aqueous solution |
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| strong electrolyte |
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| a substance that conducts electricity well in dilute aqueous solution |
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| strong base |
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| metal hydroxide that is soluble in water and dissociates completely in dilute aqueous solution |
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| ternary acid |
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| a ternary compound containing H, O, and another element, usually a nonmetal |
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| ternary compound |
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| a compound consisting of three elements; may be ionic or molecular |
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| total ionic equation |
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| an equation for a chemical reaction written to show the predominant form of all species in aqueous solution or in contact with water |
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| weak acid |
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| an acid that ionizes only slightly in dilute aqueous solution |
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| weak base |
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| a molecular substance that ionizes only slightly in water to produce an alkaline (base) solution |
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| weak electrolyte |
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| a substance that conducts electricity poorly in dilute aqueous solution |
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| absorption spectrum |
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| the spectrum associated with the absorption of electromagnetic radiation by atoms (or other species) resulting from transitions from lower to higher energy states |
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| alpha (a) particle |
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| a helium ion with a 2+ charge; an assembly of two protons and two neutrons |
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| angular momentum quantum number (l) |
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| the quantum mechanical solution to a wave equation that designates the subshell, or set of orbitals (s, p, d, f), within a given main shell in which an electron resides |
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| anode |
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| in a cathode-ray tube, the positive electrode |
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| atomic orbital |
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| the integral number of protons in the nucleus; defines the identity of an element |
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| Aufbau ("building up") Principle |
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| a guide for predicting the order in which electrons fill subshells and shells in atoms |
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| Balmer-Rydberg equation |
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| an empirical equation that relates wavelengths in the hydrogen emission spectrum to integers |
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| canal ray |
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| a stream of positively charged particles (cations) that moves toward the negative electrode in a cathode-ray tube; observed to pass through canals in the negative electrode |
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| cathode |
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| in a cathode-ray tube, the negative electrode |
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| cathode ray |
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| the beam of electrons going from the negative electrode toward the positive electrode in a cathode-ray tube |
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| cathode-ray tube |
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| a closed glass tube containing a gas under low pressure, with electrodes near the ends and a luminescent screen at the end near the positive electrode; produces cathode rays when high voltage is applied |
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| continuous spectrum |
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| the spectrum that contains all wavelengths in a specified region of the electromagnetic spectrum |
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| d orbitals |
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| beginning in the third shell, a set of five degenerate orbitals per shell, higher in energy than s and p orbitals in the same shell |
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| degenerate orbitals |
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| two or more orbitals that have the same energy |
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| diamagnetism |
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| weak repulsion by a magnetic field; associated with all electrons being paired |
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| electromagnetic radiation |
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| energy that is propagated by means of electric and magnetic fields that oscillate in directions perpendicular to the direction of travel of the energy |
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| electron |
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| a subatomic particle having a mass of 0.00054858 amu and a charge of 1- |
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| electron configuration |
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| the specific distribution of electrons in the atomic orbitals of atoms and ions |
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| electron transition |
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| the transfer of an electron from one energy level to another |
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| emission spectrum |
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| the spectrum associated with emission of electromagnetic radiation by atoms (or other species) resulting from electron transitions from higher to lower energy states |
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| excited state |
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| any energy state other than the ground state of an atom, ion, or molecule |
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| f orbitals |
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| beginning in the fourth shell, a set of seven degenerate orbitals per shell, higher in energy than s, p, and d orbitals in the same shell |
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| ferromagnetism |
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| the property that allows a substance to become permanently magnetized when placed in a magnetic field; exhibited by iron, colbalt, and nickel |
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| frequency (v) |
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| the number of crests of a wave that pass a given point per unit time |
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| fundamental particles |
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| subatomic particles of which all matter is composed; protons, electrons, and neutrons are fundamental particles |
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| ground state |
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| the lowest energy state or most stable state of an atom, molecule, or ion |
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| Heisenberg Uncertainty Principle |
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| it is impossible to determine accurately both the momentum and position of an electron simultaneously |
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| Hund's Rule |
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| each orbital of a given subshell is occupied by a single electron before pairing begins |
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| isotopes |
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| two or more forms of atoms of the same element with different masses; that is, atoms containing the same number of protons but different number of neutrons |
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| line spectrum |
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| an atomic emission or absorption |
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| magnetic quantum number (ml) |
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| quantum mechanical solution to a wave equation that designates the particular orbital within a given subshell (s, p, d, f) in which an electron resides |
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| mass spectrometer |
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| an instrument that measures the charge-to-mass ratios of charged particles |
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| natural radioactivity |
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| spontaneous decomposition of an atom |
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| neutron |
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| a subatomic nuclear particle having a mass of 1.0087 amu and no charge |
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| nucleus |
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| the very small, very dense, positively charged center of an atom containing protons and neutrons, except for 11H |
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| nuclide symbol |
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