Chemistry 101 Chapter 5

Front 1

Bond Angle

Back 1

The angle (in degrees) defined by lines joining the centers of two atoms to a third atom to which they are chemically bonded

Front 2

Valence-Shell Electron-Pair Repulsion Theory (VSEPR)

Back 2

A model predicting the arrangement of valence electron pairs around a central atom that minimizes their mutual repulsion to produce the lowest energy orientations

Front 3

Electron-Group Geometry

Back 3

The three-dimensional arrangement of bonding pairs and lone pairs of electrons about a central atom

Front 4

Molecular Geometry

Back 4

The three-dimensional arrangement of the atoms in a molecule

Front 5

Steric Number (SN)

Back 5

The sum of the number of atoms bonded to a central atom plus the number of lone pairs of electrons on the central atom

Front 6

Linear

Back 6

Molecular geometry about a central atom with a steric number of 2 and no lone pairs of electrons

Front 7

Trigonal Planar

Back 7

Molecular geometry about a central atom with a steric number of 3 and no lone pairs of electrons

Front 8

Tetrahedral

Back 8

Molecular geometry about a central atom with a steric number of 4 and no lone pairs of electrons

Front 9

Trigonal Bipyramidal

Back 9

Molecular geometry about a central atom with a steric number of 5 and no lone pairs of electrons, in which three atoms occupy equatorial sites and two other atoms occupy axial sites above and below the equatorial plane

Front 10

Octahedral

Back 10

Molecular geometry about a central atom with a steric number of 6 and no lone pairs of electrons, in which all six sites are equivalent

Front 11

Angular or Bent

Back 11

Molecular geometry about a central atom with a steric number of 3 and one lone pair of steric number 4 and two lone pairs

Front 12

Trigonal Bipyramidal

Back 12

Molecular geometry about a central atom with a steric number of 4 and one lone pair of electrons

Front 13

Seesaw

Back 13

Molecular geometry about a central atom with a steric number of 5 and one lone pair of electrons in an equatorial position; the atoms occupy two axial sites and two equatorial sites

Front 14

T-shaped

Back 14

Molecular geometry about a central atom with a steric number of 5 and two lone pairs of electrons that occupy equatorial positions; the atoms occupy two axial sites and one equatorial site

Front 15

Square Pyramidal

Back 15

Molecular geometry about a central atom with a steric of 6 and one lone pair of electrons; as typically drawn, the atoms occupy four equatorial sites and one axial site

Front 16

Square Planar

Back 16

Molecular geometry about a central atom with a steric number of 6 and two lone pairs of electrons that occupy axial sites; the atoms occupy four equatorial positions

Front 17

Bond Dipole

Back 17

Separation of electrical charge created when atoms with different electronegativities form a covalent bond

Front 18

Permanent Dipole

Back 18

Permanent separation of electrical charge in a molecule due to unequal distributions of bonding and/or lone pairs of electrons

Front 19

Dipole Moment (μ)

Back 19

A measure of the degree to which a molecule aligns itself in an applied electric field; a quantitative expression of the polarity of a molecule

Front 20

Valence Bond Theory

Back 20

A quantum mechanics-based theory of bonding that assumes covalent bonds form when half-filled orbitals on different atoms overlap or occupy the same region in space

Front 21

Overlap

Back 21

A term in valence bond theory describing bonds arising from two orbitals on different atoms that occupy the same region of space

Front 22

Sigma (σ) Bond

Back 22

A covalent bond in which the highest electron density lies between the two atoms along the bond axis

Front 23

Hybridization

Back 23

In valence bond theory, the mixing of atomic orbitals to generate new sets of orbitals that then are available to form covalent bonds with other atoms

Front 24

Hybrid Atomic Orbital

Back 24

In valence bond theory, one of a set of equivalent orbitals about an atom created when specific atomic orbitals are mixed

Front 25

sp^3 Hybrid Orbitals

Back 25

A set of four hybrid orbitals with a tetrahedral orientation produced by mixing one s and three p atomic orbitals

Front 26

sp^2 Hybrid Orbitals

Back 26

Three hybrid orbitals in a trigonal planar orientation formed by mixing one s and two p orbitals

Front 27

Pi (π) Bond

Back 27

A covalent bond in which electron density is greatest above and below the bonding axis

Front 28

sp Hybrid Orbitals

Back 28

Two hybrid orbitals on opposite sides of the hybridized atom formed by mixing one s and one p orbital

Front 29

sp^3d Hybrid Orbitals

Back 29

Five equivalent hybrid orbitals with lobes pointing toward the vertices of a trigonal bipyramid that form by mixing one s orbital, three p orbitals, and one d orbital from the same shell

Front 30

sp^3d^2 Hybrid Orbitals

Back 30

Six equivalent hybrid orbitals pointing toward the vertices of an octahedron that form by mixing one s orbital, three p orbitals, and two d orbitals from the same shell

Front 31

Molecular Recognition

Back 31

The process by which molecules interact with other molecules to produce a biological effect

Front 32

Aromatic Compound

Back 32

A cyclic, planar compound with delocalized π electrons above and below the plane of the molecule

Front 33

Isomer

Back 33

One of a group of compounds having the same chemical formula but different molecular structures

Front 34

Stereoisomerism

Back 34

Isomerism created by differences in the orientations of the bonds between atoms in molecules

Front 35

Enantiomer

Back 35

One of a pair of optical isomers of a compound

Front 36

Chiral

Back 36

Describes a molecule that is not superimposable on its mirror image

Front 37

Racemic Mixture

Back 37

A sample containing equal amounts of both enantiomers of a compound

Front 38

Molecular Orbital (MO) Theory

Back 38

A bonding theory based on the mixing of atomic orbitals of similar shapes and energies to form molecular orbitals that belong to the molecule as a whole

Front 39

Molecular Orbital

Back 39

A region of characteristic shape and energy where electrons in a molecule are located

Front 40

Bonding Orbital

Back 40

Term in MO theory describing regions of increased electron density between nuclear centers that serve to hold atoms together in molecules

Front 41

Antibonding Orbital

Back 41

Term in MO theory describing regions of electron density in a molecule that destabilize the molecule because they do not increase the electron density between nuclear centers

Front 42

Sigma (σ) Molecular Orbital

Back 42

In MO theory, the orbital that results in the highest electron density between the two bonded atoms

Front 43

Molecular Orbital Diagram

Back 43

In MO theory, an energy-level diagram showing the relative energies and electron occupancy of the molecular orbitals for a molecule

Front 44

Pi (π) Molecular Orbital

Back 44

In MO theory, an orbital formed by the mixing of atomic orbitals oriented above and below, or in front of and behind, the bonding axis; electrons in π orbitals form π bonds

Front 45

Diamagnetic

Back 45

Describes a substance with no unpaired electrons that is weakly repelled by a magnetic field

Front 46

Paramagnetic

Back 46

Describes a substance with unpaired electrons that is attracted to a magnetic field