Kinetic Molecular Theory(KMT)

• Use the Kinetic Molecular Theory to explain properties of solids, liquids and gases.

Include: intermolecular forces, elastic collisions, kinetic energy, temperature

Additional KEY Terms

Intramolecular IntermolecularCrystalline Amorphous

Kinetic Molecular Theory - explains why matter behaves as it does. The major points:

· The particles that make up matter are very small.

· There are spaces between the particles.

· The particles are in constant motion.

· There are forces of attraction between particles.

1. Intramolecular forces- within molecules. (ionic and covalent bonds involving electrons)

H

O

H

Cl -Na +

H

O

H Cl-

Na+

2. Intermolecular forces - between molecules.

· As temperature increases, the speed of particles increases.

· As temperature decreases, speed decreases.

Kinetic energy (energy of motion)of the particles increases with increasing temperature.

Elastic Collisions

Gas particles collide with the sides of the container, and exert a force.

This force is gas pressure.

3 possible options that can occur in these collisions: (With a constant temperature)

1. The collision could result in a loss of energy.FALSE

FALSE

TRUE

2. The particles would gain energy due to collisions.

3. Energy of the particles remains constant before and after the collisions.

According to KMT:

All collisions between particles and with their container are elastic.

This means there is no loss of energy.

Maxwell and Boltzman:

Not all particles, at a given temperature, have the same amount of energy.

TEMPERATURE:

The average kinetic energy of the particles is indicated by the temperature of the matter.

KMT for Gases

1. Easily compressed and have low densities:• particles of a gas must be far apart and loosely

packed.

2. NO definite volume and diffuse easy: • intermolecular forces (IMFs) - attraction /

repulsion - between the particles must be very low.

KMT for Solids

1. Not easily compressed and have a high density:• particles must be very close together already,

more particles per volume.

2. Diffusion is poor through solids: • no space between particles.

3. Definite shape and volume of solids:• Particles held together and don’t move.• very strong intermolecular forces (IMFs).

Solids come in two main forms: crystalline and amorphous.

Crystalline –particles arranged in a geometric, three-dimensional pattern.

Each element and compound has a unique crystal structure.

Crystals can be held together by ionic attraction or covalent IMFs.

NaCl

IMFs can be strong or weak, but are strongest in ionic solids.

Sugar

Amorphous (Greek for “without form”):an irregular arrangement of particles.

Crystalline Amorphous (candles, glass, rubber, plastic)

KMT for Liquids 1. Not easily compressed and have high density - • Particles still be close together and densely

packed.

2. Do not have a definite shape – • IMFs must be weaker, allowing some movement.

3. Have a definite volume – • IMFs strong enough to limit distance of particle

movement.

CAN YOU / HAVE YOU?

• Use the Kinetic Molecular Theory to explain properties of solids, liquids and gases.

Include: intermolecular forces, elastic collisions, kinetic energy, temperature

Additional KEY Terms

Intramolecular IntermolecularCrystalline Amorphous