Chapter 2 – Atoms, Molecules, and Ions Terminology – Flashcards
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| Chemical Nomenclature |
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| The relationship between the names of chemical compounds and their formulas. |
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| Organic Compounds |
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| Compounds which are based on the element carbon. |
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| Law of Conservation of Mass |
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| The total mass remains constant during a chemical reaction. |
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| Law of Constant Composition or Law of Definite Proportions |
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| All samples of a compound have the same composition: that is, all samples have the same proportions, by mass, of the elements present in the compound. |
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| Law of Multiple Proportions |
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| In two or more compounds of the same two elements, the masses of one element that combine with a fixed mass of the second element are in the ratio of small whole numbers. |
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| Revised Law of Conservation of Mass |
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| Atoms can neither be created or destroyed in a chemical reaction; thus, the total mass remains unchanged. |
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| Proton |
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| Subatomic particle which has a relative mass of 1 and carries one fundamental unit of positive electric charge, denoted 1+. |
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| Neutron |
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| Subatomic particle which has a relative mass of 1 and is an electrically neutral particle. |
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| Electron |
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| Subatomic particle which has a relative mass of 1/1836th (or 0.0005447) of the mass of a proton and carries one fundamental unit of negative electric charge denoted 1-. |
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| Nucleus |
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| Positively charged core of the atom where protons and neutrons are densely packed together. |
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| Atomic Number (Z) |
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| The number of protons in the nucleus of an atom of a given element; the number which defines the element. |
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| Isotopes |
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| Atoms that have the same number of protons but different numbers of neutrons. |
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| Mass Number (A) |
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| The sum of the numbers of protons and neutrons in an atom. The mass number is always an integral (whole) number. |
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| Atomic Mass Unit (amu) |
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| A unit which is exactly 1/12 the mass of a carbon-12 atom. 1 u = 1.66054 x 10^-24 gram. |
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| Atomic Mass |
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| The weighted average of the masses of the naturally occurring isotopes of that element. |
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| Periodic Table |
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| A chart developed by Dmitri Mendeleev in 1869 which organizes and groups elements having similar physical and chemical properties. In this arrangements, elements that most closely resemble one another in physical and chemical properties tend to fall in the same vertical group. |
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| Groups (or families) |
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| The vertical columns of elements that have similar properties on the periodic table. A group number is placed at the top of each column. |
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| Periods |
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| The horizontal rows of elements on the periodic table which vary in length from two elements (the first two) to 32 elements (the sixth and seventh periods). |
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| Metals |
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| Elements to the left of the staircase on the periodic table (except for hydrogen) which have a characteristic luster and are generally good conductors of heat and electricity. |
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| Malleable |
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| The ability for metals to be hammered into thin sheets of foil. |
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| Ductile |
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| The ability for metals to be drawn into wire. |
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| Nonmetals |
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| Elements to the right of the staircase which lack metallic properties. |
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| Metalloids (Semimetals) |
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| Some of the elements bordering the staircase which resemble metals in some properties and nonmetals in others; they are sometimes considered metalloids. |
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| Chemical Formula |
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| A symbolic representation of the composition of a compounds expressed in terms of its constituent elements. A chemical formula uses symbols to indicate which elements are present, and it uses subscripts to indicate the relative numbers of atoms of the different elements present. |
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| Molecule |
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| A group of two or more atoms held together in a definite spatial arrangement by forces called covalent bonds |
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| Molecular Compound |
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| Molecules are the smallest characteristic entities of a molecular compound which determine the properties of the substance. |
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| Empirical Formula |
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| The simplest formula we can write for a compound. It lists the elements present and indicates the smallest integral (whole-number) ratio in which atoms of these elements are combined. |
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| Molecular Formula |
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| Shows the differences between compounds with identical empirical formulas by giving the symbol and the actual number of each kind of atom in a molecule. |
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| Diatomic Molecules |
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| Molecules which can only exist in a two-atom form, such as hydrogen (H2), nitrogen (N2), oxygen (O2), and the group 7A elements, the halogens. |
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| Halogens |
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| The group 7A elements, such as F2, Cl2, Br2, and I2. |
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| Polyatomic Molecules |
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| Many-atom molecules such as sulfur (S8) and phosphorous (P4) |
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| Noble Gases |
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| The group 8A elements which exist in a monoatoic, or one-atom form. |
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| Monoatomic |
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| One-atom form, such as helium (He) and neon (Ne). |
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| Structural Formula |
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| A chemical formula that shows how atoms are attached to one another. |
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| Ball-and-Stick Model |
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| Shows the spatial arrangements of bonds in a molecular compound. |
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| Space-Filling Model |
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| Shows that atoms in a molecule occupy space and are in direct contact with one another. |
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| Binary Molecular Compound |
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| A compound composed of two nonmetal elements. |
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| Ion |
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| When an atom or group of bonded atoms may lose or gain one or more electrons, thereby acquiring a net electric charge and becoming an ion. Ions are formed only through the loss or gain of electrons; there is no change in the number of protons in the nucleus of the atom. |
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| Monoatomic Ions |
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| Formed when a single atom loses or gains one or more electrons. |
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| Cations |
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| Positively charged ions. |
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| Anions |
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| Negatively charged ions. |
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| Ionic Compounds |
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| Oppositely charged ions (cations and anions) which attract one another and are held together in huge clusters by electrostatic attractions. |
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| Alkali Metals |
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| The group 1A elements which give up one electron to form cations with charge 1+. |
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| Alkaline Earth Metals |
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| The group 2A elements which give up two electrons to form cations with 2+ charge. |
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| Binary Ionic Compound |
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| A compound composed of two or more nonmetal-and-metal or metal-and-metal compounds. |
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| Formula Unit |
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| A hypothetical unit used for binary ionic compounds which expresses the simplest collection of cations and anions to represent an electrically neutral unit. |
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| Polyatomic Ion |
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| A charge group of bonded atoms. |
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| -ite |
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| An anion with this suffix generally has one fewer oxygen atom and the same charge as an anion with a name ending in -ate. |
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| hypo- |
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| An anion with this prefix has one fewer oxygen atom than the -ite anion. |
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| per- |
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| An anion with this prefix has one more oxygen atom than the -ate anion. |
