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