- axial position
- location in a trigonal bipyramidal geometry in which there is another atom at a 180° angle and the equatorial positions are at a 90° angle
- bond angle
- angle between any two covalent bonds that share a common atom
- bond dipole moment
- separation of charge in a bond that depends on the difference in electronegativity and the bond distance represented by partial charges or a vector
- bond distance
- (also, bond length) distance between the nuclei of two bonded atoms
- bond energy
- (also, bond dissociation energy) energy required to break a covalent bond in a gaseous substance
- bond length
- distance between the nuclei of two bonded atoms at which the lowest potential energy is achieved
- Born-Haber cycle
- thermochemical cycle relating the various energetic steps involved in the formation of an ionic solid from the relevant elements
- covalent bond
- bond formed when electrons are shared between atoms
- dipole moment
- property of a molecule that describes the separation of charge determined by the sum of the individual bond moments based on the molecular structure
- double bond
- covalent bond in which two pairs of electrons are shared between two atoms
- electron-pair geometry
- arrangement around a central atom of all regions of electron density (bonds, lone pairs, or unpaired electrons)
- electronegativity
- tendency of an atom to attract electrons in a bond to itself
- equatorial position
- one of the three positions in a trigonal bipyramidal geometry with 120° angles between them; the axial positions are located at a 90° angle
- formal charge
- charge that would result on an atom by taking the number of valence electrons on the neutral atom and subtracting the nonbonding electrons and the number of bonds (one-half of the bonding electrons)
- free radical
- molecule that contains an odd number of electrons
- hypervalent molecule
- molecule containing at least one main group element that has more than eight electrons in its valence shell
- inert pair effect
- tendency of heavy atoms to form ions in which their valence s electrons are not lost
- ionic bond
- strong electrostatic force of attraction between cations and anions in an ionic compound
- lattice energy (ΔHlattice)
- energy required to separate one mole of an ionic solid into its component gaseous ions
- Lewis structure
- diagram showing lone pairs and bonding pairs of electrons in a molecule or an ion
- Lewis symbol
- symbol for an element or monatomic ion that uses a dot to represent each valence electron in the element or ion
- linear
- shape in which two outside groups are placed on opposite sides of a central atom
- lone pair
- two (a pair of) valence electrons that are not used to form a covalent bond
- molecular structure
- arrangement of atoms in a molecule or ion
- molecular structure
- structure that includes only the placement of the atoms in the molecule
- octahedral
- shape in which six outside groups are placed around a central atom such that a three-dimensional shape is generated with four groups forming a square and the other two forming the apex of two pyramids, one above and one below the square plane
- octet rule
- guideline that states main group atoms will form structures in which eight valence electrons interact with each nucleus, counting bonding electrons as interacting with both atoms connected by the bond
- polar covalent bond
- covalent bond between atoms of different electronegativities; a covalent bond with a positive end and a negative end
- polar molecule
- (also, dipole) molecule with an overall dipole moment
- pure covalent bond
- (also, nonpolar covalent bond) covalent bond between atoms of identical electronegativities
- resonance
- situation in which one Lewis structure is insufficient to describe the bonding in a molecule and the average of multiple structures is observed
- resonance forms
- two or more Lewis structures that have the same arrangement of atoms but different arrangements of electrons
- resonance hybrid
- average of the resonance forms shown by the individual Lewis structures
- single bond
- bond in which a single pair of electrons is shared between two atoms
- tetrahedral
- shape in which four outside groups are placed around a central atom such that a three-dimensional shape is generated with four corners and 109.5° angles between each pair and the central atom
- trigonal bipyramidal
- shape in which five outside groups are placed around a central atom such that three form a flat triangle with 120° angles between each pair and the central atom, and the other two form the apex of two pyramids, one above and one below the triangular plane
- trigonal planar
- shape in which three outside groups are placed in a flat triangle around a central atom with 120° angles between each pair and the central atom
- triple bond
- bond in which three pairs of electrons are shared between two atoms
- valence shell electron-pair repulsion theory (VSEPR)
- theory used to predict the bond angles in a molecule based on positioning regions of high electron density as far apart as possible to minimize electrostatic repulsion
- vector
- quantity having magnitude and direction