7.8: Key Terms
- Page ID
- 452471
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| Words (or words that have the same definition) | The definition is case sensitive | (Optional) Image to display with the definition [Not displayed in Glossary, only in pop-up on pages] | (Optional) Caption for Image | (Optional) External or Internal Link | (Optional) Source for Definition |
|---|---|---|---|---|---|
| (Eg. "Genetic, Hereditary, DNA ...") | (Eg. "Relating to genes or heredity") |  | The infamous double helix | https://bio.libretexts.org/ | CC-BY-SA; Delmar Larsen |
| Word(s) | Definition | Image | Caption | Link | Source |
|---|---|---|---|---|---|
| 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 |