Glossary of Key Terms

The following is a list of key terms and the accompanying definitions for the matter, chemical trends, and chemical bonding unit.

Alkali: a base that is soluble in water
Atomic mass unit: one twelfth of the mass of a carbon-12 atom
Atomic radius: the distance from the centre of an atom to the boundary within which the electrons spend 90 percent of their time
Boiling point: the temperature at which a compound changes from a liquid to a gas
Bonding pair: a pair of electrons that is shared by two atoms, thus forming a covalent bond
Covalent bond: the attraction between atoms that results from the sharing of electron
Dipole: a molecule with a slightly positively charged end (positive pole) and a slightly negatively charged end (negative pole)
Dipole-dipole force: the attractive force between the positive end of one molecule and the negative end of another molecule
Double bond: a covalent bond that results from atoms sharing two pairs of electrons
Effective nuclear charge: the apparent nuclear charge, as experienced by the outermost electrons of an atom, as a result of the shielding by the inner-shell electrons
Electrical conductivity: the ability of a substance or an object to allow an electric current to exist within it
Electron affinity: the energy absorbed or released when an electron is added to a neutral atom
Electronegativity: an indicator of the relative ability of an atom to attract shared electrons
Electronegativity difference: the difference between the electronegativities of two atoms
Electron pairs: two electrons that are interacting in a unique way, allowing them to be situated close to each other
Group: a column in the periodic table
Intermolecular forces: attractive forces that act between molecules
Ionic bond: the attractive electrostatic force between a negative ion and a positive ion
Ionic compound: a chemical compound composed of ions that are held together by ionic bonds
Ionization energy: the amount of energy required to remove the outermost electron from an atom or ion in the gaseous state
Isotopic abundance: the amount of a given isotope of an element that exists in nature, expressed as a percentage of the total amount of this element
Isotopes: atoms that have the same number of protons but different numbers of neutrons
Lone pair: a pair of electrons that is not part of a covalent bond
Lewis diagram: a model of an atom that has the chemical symbol for the element surrounded by dots to represent the valence electrons of the element
Lewis structure: a Lewis diagram that portrays a complete molecular compound
Melting point: the temperature at which a compound changes from a solid to a liquid
Molecular compound: a chemical compound that is held together by covalent bonds
Octet Rule: a “rule of thumb” that allows you to predict the way in which bonds will form between atoms
Oxoacid: an acid composed of hydrogen, oxygen, and atoms of at least one other element
Period: a row in the periodic table
Periodic law: a statement that describes the repeating nature of the properties of the elements
Polar covalent bond: a covalent bond around which there is an uneven distribution of electrons, making one end slightly positively charged and the other end slightly negatively charged
Polyatomic ion: a molecular compound that has an excess or a deficit of electrons, and thus has a charge
Radioisotopes: isotopes with unstable nuclei that decay into different, often stable, isotopes
Single bond: a covalent bond that results from atoms sharing one pair of electrons
Structural Formula: a diagram that has the chemical symbols connected by lines to show the connections among atoms in a chemical compound
Triple bond a covalent bond that results from atoms sharing three pairs of electrons
Unpaired electrons: electrons in an unfilled outer shell that are not part of a pair and are, therefore, more likely to participate in bonds with other atoms
Valence Electrons: electrons in the outermost shell of an atom

Douglass, S. et al. (2010). Chemistry 11. McGraw-Hill Ryerson.

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