Chemical Bonding Chap. 6
Jan 18, 2016
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