Chemical Bonding

Molecular Geometry

Ch. 6 Sections 1-4 Review

1. In general, what determines whether atoms will form chemical bonds?

Atoms will form a chemical bond if their potential energy is lowered in doing so.

2. Describe the difference between ionic and covalent bonding.

Ionic bonds form as a result of the transfer of electrons between two atoms with a large difference in electronegativity. Covalent bonds form when electrons are shared between two atoms of similar or slightly different electronegativity.

Ch. 6 Sections 1-4 Review3. What types of bonds form between the

following pairs of atoms: Ca-Cl, O-H, O-O?Ionic, polar covalent, nonpolar covalent

4. What is the meaning of the word polar, as applied to chemical bonding?

Polar refers to bonds that have an uneven distribution of charge.

5. What type of bonding exists (ionic or covalent) in the compounds: NaCl, H2O, CH4?

Ionic, covalent, covalent

Ch. 6 Sections 1-4 Review6. List 3 properties of ionic compounds.

Hardness, brittleness, electrical conductivity in molten state, high melting and boiling points.

7. What accounts for the properties of ionic compounds listed above?

Cations and anions are arranged in a crystal lattice.

8. Draw the Lewis dot diagram for C3H6.

Ch. 6 Sections 1-4 Review9. How are single, double, and triple covalent

bonds different?One, two, and three pairs of electrons are shared; bond

energy increases with the number of bonds and bond length decreases with the number of bonds.

10.Draw the Lewis dot structure for SO2. Show both resonance structures.

Ch. 6 Sections 1-4 Review11.What properties of metals contribute to their

tendency to form metallic bonds?Most metals have unfilled outermost orbitals, low

ionization energies, and low electronegativities.

12.What are some common properties of metals?Electrical and thermal conductivity, luster, malleability,

ductility, high melting and boiling points

HybridizationHybridization – mixing of atomic orbitals of

similar energy to produce new orbitals of equal energy

Hybridization

Intermolecular Forces

• Covalent, ionic, and metallic bonds can be considered to be intra-molecular forces

Intermolecular Forces- forces of attraction between molecules; weaker than covalent, ionic, and metallic bonds.

Boiling Points and Bonding TypesBonding Type Substance B.P. (1 atm) in oC

Nonpolar covalent H2 -253

O2 -183

Cl2 -34

Br2 59

CH4 -164

CCl4 77

C6H6 80

Polar Covalent PH3 -88

NH3 -33

H2S -61

H2O 100

HF 20

HCl -85

ICl 97

Boiling Points and Bonding Types

Bonding Type Substance B.P. (1 atm) in oC

Ionic NaCl 1413

MgF2 2239

Metallic Cu 2567

Fe 2750

W 5660

Molecular Polarity• Molecular polarity depends on the polarity of the

bonds that make up a compound and the molecular shape.

• A dipole moment results when a polar molecule has a center for positive charge separate from a center for negative charge