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 Rule Each atom needs 8 valence e - to be stable, bonding achieves this (Elements 1-5 only 2 e - )

Lewis structures Ionic - shows transfer of e - ’s in reaction format with charges Covalent - connects dots or uses a solid line to show orbital overlap singledoubletriple 1 pair2 pairs 3 pairs

Octet Rule exceptions Halogens can force bonding Ex: PBr 5 RnI 6

An atom uses an electron pair from another atom, weak bond (Oxygen does it a lot) Ex: O 3 SO 3 Coordinate Covalent bond

Polyatomic ions Several atoms covalently bonded, but they have an ion charge from the loss or gain of e- on the central atom Ex: NH 4 +1 NO 3 -1

V.S.E.P.R. Theory e - pairs get as far apart as possible Valence repulsion pair electron shell

hybrid sp sp 2 sp 3 sp 3 d sp 3 d 2

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