C. Johannesson I II III IV

Chemical Bonding

Molecular Compounds

C. Johannesson

A. Energy of Bond FormationPotential Energy

based on position of an object low PE =

high stability

C. Johannesson

no interaction

attraction vs. repulsion

increased attraction

A. Energy of Bond FormationPotential Energy Diagram

C. Johannesson

balanced attraction & repulsion

increased repulsion

attraction vs. repulsion

A. Energy of Bond FormationPotential Energy Diagram

C. Johannesson

Bond Energy

A. Energy of Bond Formation

Bond Length

Bond Energy Energy required to break a bond

C. Johannesson

A. Energy of Bond FormationBond Energy

Short bond = high bond energy

C. Johannesson

B. Lewis StructuresElectron Dot Diagrams

show valence e- as dots distribute dots like arrows

in an orbital diagram 4 sides = 1 s-orbital, 3 p-orbitals EX: oxygen

2s 2pO

X

C. Johannesson

B. Lewis StructuresOctet Rule

Most atoms form bonds in order to obtain 8 valence e-

Full energy level stability ~ Noble Gases

Ne

C. Johannesson

+ -

+

B. Lewis StructuresNonpolar Covalent - no charges

Polar Covalent - partial charges

C. Johannesson

C. Molecular NomenclaturePrefix System (binary compounds)

1. Less e-neg atom comes first.

2. Add prefixes to indicate # of atoms. Omit mono- prefix on first element.

3. Change the ending of the second element to -ide.

C. Johannesson

PREFIXmono-di-tri-tetra-penta-hexa-hepta-octa-nona-deca-

NUMBER12345678910

C. Molecular Nomenclature

C. Johannesson

CCl4

N2O

SF6

carbon tetrachloride

dinitrogen monoxide

sulfur hexafluoride

C. Molecular Nomenclature

C. Johannesson

arsenic trichloride

dinitrogen pentoxide

tetraphosphorus decoxide

AsCl3

N2O5

P4O10

C. Molecular Nomenclature

C. Johannesson

N O FClBrI

H

C. Molecular NomenclatureThe Seven Diatomic Elements

Br2 I2 N2 Cl2 H2 O2 F2