Chapters 5/6 Chemical Bonding

2 Types of bonds A + B A:B Shared Pair Covalent A+ :B- Ionic . .

Bonding Types Ionic 3.3 2.1 0.5 0.0 Polar Covalent 100% 50% 5% 0% Percent Ionic 100% 50% 5% 0% Difference in Electronegativity 3.3 2.1 0.5 0.0 Ionic Nonpolar Covalent Polar Covalent

Types of Bonds Cs - F 4.0 – 0.7 = 3.3 Ionic Bond 3.0 – 2.1 = 0.9 H - Cl Polar Covalent H - H 2.1 – 2.1 = 0.0 Nonpolar Covalent

Polar Covalent d+ d- Polar Covalent – unequal sharing Shared electron cloud Cl H d+ d- (Slightly positive) (Slightly negative) Polar Covalent – unequal sharing

Nonpolar Covalent H H Nonpolar Covalent – equal sharing

Properties of ionic compounds Composed of positive and negative ions Ionic compounds form crystals

Ionic vs. Covalent compounds Harder Higher melting point Higher boiling point Form crystals Form electrolytes Salt Lower melting point Lower boiling point Doesn’t form electrolytes Sugar

Metallic bonds Sheet of positive ions surrounded by mobile electrons

Metallic bonding Electrons are randomly spaced Properties of metals Free to move around Good conductors of heat and electricity Called “electron sea” Properties of metals Malleable – able to be bent or shaped Ductile – able to be drawn into a wire

VSEPR Valence shell electron pair repulsion theory Linear – AB2 Electrons want to be as far apart as possible “molecular geometry” Linear – AB2 Bent – AB2e2 Triangular Planar – AB3 Tetrahedral – AB4