Forces of AttractionObjectives:

1. State the kinetic theory of matter.

2. Describe and compare types of intramolecular and intermolecular

forces.

Vocabulary Building/Review

1. What is the difference between intra- and inter-?

2. What are 3 types of forces (aka, bonds) that hold particles (or atoms) together?

Intramolecular Forces

Def.: attractive forces that hold particles (atoms) together in ionic, covalent, and metallic bonds

3 types: (examples of each?)

1. Ionic – between _______ and _________.

2. Covalent: b/t (+) nuclei and (-) electrons

3. Metallic: b/t metal cations(?) and mobile(?) electrons

Intermolecular Forces

Hold molecules(?) together 3 types:

1. Dispersion/London forces

2. Dipole-dipole forces

3. Hydrogen bonds

1. Dispersion/London Forces

Weak forces between “identical nonpolar molecules”

(diatomic molecules) Examples? Results from the shifting of electrons in the

electron clouds What are the states of matter of the

halogens? Explain why…….

2. Dipole-dipole Forces Between polar molecules:

molecules formed from different elements Some elements are more electronegative than

others, and will be the “(-) end” of the molecule, while the other end is more (+).

Slightly stronger than dispersion forces, but still pretty weak.

Example: HCl (Which atom would have the negative charge?)

3. Hydrogen Bonds

A dipole-dipole attraction between hydrogen and “a small, highly electronegative atom with at least one lone electron pair” (F, O, or N)

Example???

Review and Apply

1. What types of intermolecular forces must be overcome to:

a. melt ice?

b. boil water?

c. melt NaCl?

d. sublime I2?

Review and Apply, continued….

2. Which of the following compounds can form dipole-dipole forces?

a. Cl2 c. NO

b. CO d. CH4

3. Which of the following molecules can form hydrogen bonds? Which would have only dispersion forces?

a. H2 c. NH3

b. HCl d. HF