Definitions
Allotropes Chemistry variety of a substance consisting of only one type of atom (graphite, diamond) Atom A submicroscopic particle that constitutes fundamental building block of ordinary matter; smallest identifiable unit of an element. Molecule Two or more atoms joined chemically in a specific geometrical arrangement. Isomers - two or more substances that are composed of the same elements in the same proportions but differ in properties because of the arrangement of atoms. Isotope Atoms of the same element with the same number of protons but different numbers of neutrons and consequently different masses. Polymers made of many molecules strung together to make long chains Isoelectronic two elements with same electron configuration (similar properties result) Electropositive measure of an elements ability to donate electrons (metals). Octet rule Tendency for most bonded atoms to possess or share electrons eight in their outer shell to obtain stable electron configurations and lower their potential energy. Dipole moment a measure of the separation of positive and negative charge in a molecule. Covalent bond atoms share electrons that interact with the nuclei, lower potential energy through electrostatic interactions. Ionic bond formed between two oppositely charged ions (usually metal cation and nonmetallic anion) attracted to each other by electrostatic forces. Polar covalent bond bond between two atoms with significantly different electronegativities, resulting in uneven distribution of electron density. Pi bond bond formed between two p orbitals that overlap side to side. Sigma bond bond that forms between a combination of any two s, p, or hybridized orbitals that overlap end to end. Hybridization mathematical procedure in which standard atomic orbitals are combined to form new, hybrid orbitals.