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actinide
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inner transition metal in the bottom of the bottom two rows of the periodic table
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alkali metal
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element in group 1
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alkaline earth metal
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element in group 2
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alpha particle (α particle)
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positively charged particle consisting of two protons and two neutrons
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anion
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negatively charged atom or molecule (contains more electrons than protons)
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atomic mass
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average mass of atoms of an element, expressed in amu
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atomic mass unit (amu)
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(also, unified atomic mass unit, u, or Dalton, Da) unit of mass equal to of the mass of a
12
C atom
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atomic number (Z)
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number of protons in the nucleus of an atom
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binary acid
|
compound that contains hydrogen and one other element, bonded in a way that imparts acidic properties to the compound (ability to release H
+
ions when dissolved in water)
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binary compound
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compound containing two different elements.
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cation
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positively charged atom or molecule (contains fewer electrons than protons)
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chalcogen
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element in group 16
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chemical symbol
|
one-, two-, or three-letter abbreviation used to represent an element or its atoms
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covalent bond
|
attractive force between the nuclei of a molecule’s atoms and pairs of electrons between the atoms
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covalent compound
|
(also, molecular compound) composed of molecules formed by atoms of two or more different elements
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Dalton (Da)
|
alternative unit equivalent to the atomic mass unit
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Dalton’s atomic theory
|
set of postulates that established the fundamental properties of atoms
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electron
|
negatively charged, subatomic particle of relatively low mass located outside the nucleus
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empirical formula
|
formula showing the composition of a compound given as the simplest whole-number ratio of atoms
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fundamental unit of charge
|
(also called the elementary charge) equals the magnitude of the charge of an electron (e) with e = 1.602 10
−19
C
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group
|
vertical column of the periodic table
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halogen
|
element in group 17
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hydrate
|
compound containing one or more water molecules bound within its crystals
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inert gas
|
(also, noble gas) element in group 18
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inner transition metal
|
(also, lanthanide or actinide) element in the bottom two rows; if in the first row, also called lanthanide, or if in the second row, also called actinide
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ion
|
electrically charged atom or molecule (contains unequal numbers of protons and electrons)
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ionic bond
|
electrostatic forces of attraction between the oppositely charged ions of an ionic compound
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ionic compound
|
compound composed of cations and anions combined in ratios, yielding an electrically neutral substance
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isomers
|
compounds with the same chemical formula but different structures
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isotopes
|
atoms that contain the same number of protons but different numbers of neutrons
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lanthanide
|
inner transition metal in the top of the bottom two rows of the periodic table
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law of constant composition
|
(also, law of definite proportions) all samples of a pure compound contain the same elements in the same proportions by mass
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law of definite proportions
|
(also, law of constant composition) all samples of a pure compound contain the same elements in the same proportions by mass
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law of multiple proportions
|
when two elements react to form more than one compound, a fixed mass of one element will react with masses of the other element in a ratio of small whole numbers
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main-group element
|
(also, representative element) element in groups 1, 2, and 13–18
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mass number (A)
|
sum of the numbers of neutrons and protons in the nucleus of an atom
|
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metal
|
element that is shiny, malleable, good conductor of heat and electricity
|
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metalloid
|
element that conducts heat and electricity moderately well, and possesses some properties of metals and some properties of nonmetals
|
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molecular compound
|
(also, covalent compound) composed of molecules formed by atoms of two or more different elements
|
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molecular formula
|
formula indicating the composition of a molecule of a compound and giving the actual number of atoms of each element in a molecule of the compound.
|
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monatomic ion
|
ion composed of a single atom
|
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neutron
|
uncharged, subatomic particle located in the nucleus
|
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noble gas
|
(also, inert gas) element in group 18
|
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nomenclature
|
system of rules for naming objects of interest
|
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nonmetal
|
element that appears dull, poor conductor of heat and electricity
|
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nucleus
|
massive, positively charged center of an atom made up of protons and neutrons
|
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oxyacid
|
compound that contains hydrogen, oxygen, and one other element, bonded in a way that imparts acidic properties to the compound (ability to release H
+
ions when dissolved in water)
|
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|
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oxyanion
|
polyatomic anion composed of a central atom bonded to oxygen atoms
|
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period
|
(also, series) horizontal row of the periodic table
|
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periodic law
|
properties of the elements are periodic function of their atomic numbers.
|
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periodic table
|
table of the elements that places elements with similar chemical properties close together
|
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pnictogen
|
element in group 15
|
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polyatomic ion
|
ion composed of more than one atom
|
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proton
|
positively charged, subatomic particle located in the nucleus
|
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|
|
representative element
|
(also, main-group element) element in columns 1, 2, and 12–18
|
|
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series
|
(also, period) horizontal row of the period table
|
|
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spatial isomers
|
compounds in which the relative orientations of the atoms in space differ
|
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structural formula
|
shows the atoms in a molecule and how they are connected
|
|
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|
structural isomer
|
one of two substances that have the same molecular formula but different physical and chemical properties because their atoms are bonded differently
|
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|
transition metal
|
element in groups 3–12 (more strictly defined, 3–11; see chapter on transition metals and coordination chemistry)
|
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|
unified atomic mass unit (u)
|
alternative unit equivalent to the atomic mass unit
|
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|
|