Chemistry Chapter 10

Front 1

Lewis Structure (Lewis formula)

Back 1

two dimensional structural formula consists of electron-dot symbols that depict each atom and its neighbors, the bonding pairs that hold them together, and the lone pairs that fill each atom's outer level (valence level).

Front 2

resonance structures

Back 2

one of two or more lewis structures for a moleculethat cannot be adequately depicted by a single structure. They differ only in the position of bonding and lone electron pairs.

Front 3

resonance hybrid

Back 3

an average of the resonance forms, the actual molecule

Front 4

electron-pair delocalization

Back 4

the process by which electron density is spread over several atoms rather than remaining between two.

Front 5

localized

Back 5

the electron pair is attracted by the nuclei of the two bondd atoms, adn teh electron density is greatest in the region between the nuclei.

Front 6

partial bond

Back 6

the contribution from one of the localized pairs

Front 7

bond order

Back 7

number of electron pairs/ number of bonded-atom pairs.

Front 8

formal charge

Back 8

the charge an atom would have if hte bonding electrons were shared equally.

Front 9

electron deficient

Back 9

molecules that have fewer than eight electrons around he Be of B atom, ex. gaseous molecules containing either Be or B as the central atom.

Front 10

free radicals

Back 10

contain a lone (unpaired) electron, which makes them paramagnetic and extremely reactive. Molecules that contain a central atom with an odd number of valence electrons.

Front 11

expanded valence shells

Back 11

occur only witha large central nonmetal atom in whihc d orbitals are available, that is, one from Period 3 or higher.(ex. SF6)

Front 12

valence-shell electron-pair repulsion theory

Back 12

each group of valence elctrons around a central atom is located as far away as possible from the others in order to minimize repulztions.

Front 13

group of electrons

Back 13

any number of electrons that occupy a localized reagion around an atom.

Front 14

electron-group arrangement

Back 14

defined by the valence-electron groups, both bonding and nonbonding, around the central atom.

Front 15

molecular shape

Back 15

defined by the relative positions of the atomic nuclei

Front 16

molecular shape

Back 16

defined by the relative positions of the atomic nuclei.

Front 17

bond angle

Back 17

the angle formed by the nuclei of two surrounding atoms with the nucleus of the central atom at the vertex.

Front 18

linear arrangement

Back 18

the geometric arrangement obtained when two electron groups maximize their separation around a central atom.

Front 19

linear shape

Back 19

the geometric shape formed by three atoms lying in a straight line with a bond angle of 180 degrees (shape class AX2 or AX2E3).

Front 20

triangular planar arrangement

Back 20

the geometric arrangement formed when three electron groups maximize their separation around a central atom.

Front 21

trigonal planar

Back 21

when all three groups are bonding groups, the molecular shape is this (AX3; ideal bond angle 120 degrees).

Front 22

bent shape

Back 22

a molecular shape that arises when a central atom is bonded to two toher atoms and has one or two lone pairs; occurs as the AX2E shape class (bond angle<120) in the trigonal planar arrangement and as the AX2E2 shape classe (bond angle <109.5 degrees) in the tetrahedral arrangement.

Front 23

tetrahedral arrangement

Back 23

the geometric arrangement fromed when four electron groups maximize their separation aroud a central atom. (form tetrahedral shape with AX4 and bond angle 109.5 degrees)

Front 24

trigonal planar

Back 24

a tetrahedron with one vertex "missing", when one of the four electron groups in the tetrahedral arrangement is a lone pair.

Front 25

trigonal bipyramidal arrangement

Back 25

the geometric arrangement formed when five electron groups maximize their separation around a central atom. When all five groups are bonding groups the molecular shape is trigonal bipyramidal (AX5; ideal bond angles, axial-central-equatorial 120 degree)(PCl5)

Front 26

equatorial groups

Back 26

an atom or group that lies in the trigonal plane of atrigonal bipyramidal moelcuel, or a similar structural feature in a molecule

Front 27

axial group

Back 27

an atom or group that lies aboce or below the trigonal plane of a trigaonal bipyramidal moelcule, or a similar structural feature in a molecule.

Front 28

seesaw shape

Back 28

a molecular shape caused by the presence of one equatorial lone pair in a trigonal bipyramidal arrangement. (ex. SF4)

Front 29

T shape

Back 29

a molecular shape casued by the presence of two equatorial lone pairs in a trigonal bipyramidal arrangement.

Front 30

octahedral arrangement

Back 30

the geometric arrangement obtained when six electron groups maximize their space around a central atoms; when all six groups are bonding groups, the molecular shape is octahedral (AX6; ideal bond angle 90 degrees), ex SF6

Front 31

square pyramidal shape

Back 31

a molecular shape (AX5E) caused by the prescence of one lone pair in an octahedral arrangement. (ex. IP5)

Front 32

square planar shape

Back 32

a molecule shape (AX4E2) caused by the presence of two lone pairs at opposite vertices in an octahedral arrnagement.(ex. XeF4)

Front 33

molecular polarity

Back 33

molecules with a net imbalance of charge have this

Front 34

dipole moment

Back 34

in an electric field, polar molecules become oriented, on average, with their partial charges pointing toward the oppositely charged electric plates, the porduct of these partial charges and the distance between them.