Chemistry - Ch 9

Question 1

Bond angles

Answer 1

the angles made by the lines joining the nuclei of the atoms in the molecule

Question 2

Valence-shell electron-pair repulsion (VSEPR) model

Answer 2

a model that accounts for the geometric arrangements of shared and unshared electron pairs around a central atom in terms of the repulsions between electron pairs

Question 3

Bonding pair

Answer 3

in a Lewis structure, a pair of electrons that is shared by two atoms

Question 4

Electron domain

Answer 4

a region in which the electrons will most likely be found

Question 5

Nonbonding pair (lone pair)

Answer 5

electron domain that is located principally on one atom

Question 6

Electron-domain geometry

Answer 6

the arrangement of electron domains about the central atom of an ABn molecule or ione

Question 7

molecular geometry

Answer 7

arrangement of only the atoms in a molecule or ion (any nonbonding pairs are not part of the description of the molecular geometry

Question 8

bond dipole

Answer 8

dipole moment that is due only to the two atoms in that bond

Question 9

Valence bond theory

Answer 9

model of chemical bonding that marries Lewis’ notion of electron-pair bonds and the idea of atomic orbitals

Question 10

Hybrid orbitals

Answer 10

an orbital that results from the mixing of different kinds of atomic orbitals on the same atom

Question 11

Hybridization

Answer 11

process of mixing atomic orbitals

Question 12

Sigma bonds

Answer 12

a covalent bond in which electron density is concentrated along the internuclear axis

Question 13

Pi bond

Answer 13

covalent bond in which the overlap regions lie above and below the internuclear axis

Question 14

Delocalized

Answer 14

electrons that are spread over a number of atoms in a molecule rather than localized between a pair of atoms

Question 15

Molecular orbital theory

Answer 15

describes the electrons in molecules by using specific wave functions called molecular orbitals

Question 16

Molecular orbitals (MO)

Answer 16

an allowed state for an electron in a molecule; according to molecular-orbital theory, a molecular orbital is entirely analogous to an atomic orbital, which is an allowed state for an electron in an atom; most bonding orbitals can be classified as sigma or pi, depending on the disposition of electron density with respect to the internuclear axis

Question 17

Bonding molecular orbital

Answer 17

a molecular orbital in which the electron density is concentrated in the internuclear region; the energy a bonding molecular orbital is lower than the energy of the separate atomic orbitals from which it forms

Question 18

antibonding molecular orbital

Answer 18

a molecular orbital in which electron density is concentrated outside the region between the two nuclei of bonded atoms; such orbitals, designated as sigma or pi, are less stable (of higher energy) than bonding molecular orbitals

Question 19

Sigma molecular orbitals

Answer 19

a molecular orbital that centers the electron density about an imaginary line passing through two nuclei

Question 20

Energy-level diagram (molecular orbital diagram)

Answer 20

diagram showing the interacting atomic orbitals in the left and right columns and the molecular orbitals in the middle column

Question 21

Bond order

Answer 21

half the difference between the number of bonding electrons and the number of antibonding electrons

Question 22

Pi molecular orbitals

Answer 22

a molecular orbital that concentrates the electron density on opposite sides of an imaginary line that passes through the nuclei

Question 23

Paramagnetism

Answer 23

a property that a substance possesses if it contains one or more unpaired electrons; a paramagnetic substance is drawn into a magnetic field

Question 24

Diamagnetism

Answer 24

property a substance possesses if it has no unpaired electrons; weakly repelled from a magnetic field