Chemical Bonding

Chap. 6

What is a bond?

a strong attractive force that exists between the e- of certain atoms.

1

Metallic Bond (elements)

forms a hard crystal structure held together by

delocalized e- (free moving), makes metals good conductors

Ionic Bond 

- Transfer of e- from metal atom to nonmetal atom

Results in cations(+) and anions(-)

Electrostatic force, attraction of charges, holds the bond together

Covalent Bond

Sharing of e- between 2 nonmetal atoms

nonpolar if e- are equally shared

polar if e- are unequally shared

Specific Bond type

Take the difference in electronegativity of the two

elements involved in the bond

The Octet RuleEach atom needs 8 valence

e- to be stable, bonding achieves this

(Elements 1-5 only 2 e-)

Lewis structuresIonic - shows transfer of e-’s in

reaction format with charges

Covalent - connects dots or uses a solid line to show orbital overlapsingle double triple

1 pair 2 pairs 3 pairs

Octet Rule exceptions

Halogens can force bonding

Ex: PBr5 RnI6

An atom uses an electron pair from another atom, weak bond (Oxygen does it a lot)

Ex: O3 SO3

Coordinate Covalent bond

Polyatomic ionsSeveral atoms covalently bonded,

but they have an ion charge from the loss or gain of e- on the central atom

Ex: NH4+1 NO3

-1

V.S.E.P.R. Theory

 

e- pairs get as far apart as possible

Valence repulsion pair electron shell

hybrid

sp

sp2

sp3

sp3d

sp3d2

Electron Geometry Shape given by the number of

bonded and unbonded areas around the central atom

Double and triple bonds count as

1 bonded area

Molecular Geometry Shape given by the bonded pairs

This determines molecule polarity

Nonpolar bonds = Nonpolar molecule

Polar bonds = Polar molecule or Nonpolar molecule if the shape is

symmetrical