Kinetic Theory of Matter States of Matter: A Physical Change

Changes in the state of matter Are physical changes, not chemical changes. A molecule of water vapor has the same chemical composition, H 2 O, as a molecule of liquid water or a molecule of ice.

Kinetic energy The energy an object possesses because of its motion. KE = mv 2 / 2

Memorize The Theory All matter is made up of particles. These particles are in constant random motion. They collide with each other and with the wall of their container.

Physical Change Changes in the state of matter are physical changes, not chemical changes. A molecule of water vapor has the same chemical composition, H 2 O, as a molecule of liquid water or a molecule of ice.

Particle Motion in a Solid Solid- a substance whose particles have a low kinetic energy. The particles of a solid are held close together by intermolecular forces of attraction. Because the particles are so close together, they appear to vibrate around a fixed point.

Temp Increase in a Solid Velocity of the particles increases. The collisions between the particles occur with greater force, causing the particles to more farther apart. The ordered arrangement of the solid breaks down and a change in physical state occurs.

Particle Motion in a Liquid Liquid - a substance whose particles have enough kinetic energy to stretch the intermolecular forces of attraction. Collisions between the particles a strong enough to force the particles apart. The particles appear to have a moving vibration because they are still under the influence of the intermolecular forces of attraction.

Temp increase in a Liquid The velocity of the particles increases. The collisions eventually become so great that the particles break all intermolecular forces, begin moving independently between collisions, and A change in physical state occurs.

Particle Motion in a Gas Gas - a substance whose particles have enough kinetic energy to break all intermolecular forces of attraction. The particles of a gas move independently of each other. The particles move at random because they have overcome the intermolecular forces of attraction.

Temp Increase in a Gas When a gas is raised to extreme temperatures, over 5000 o C, they have so much kinetic energy that their collisions will break electrons out of the atoms, and a change in physical state occurs.

Plasma (a special form of gas) Plasma can be defined as a charged gas. The particle collisions are violent enough to break electrons out of the atoms, producing particles with charges (electrons and positive ions).

Temperature: A measure of the average kinetic energy of the particles of matter. Thermometer

Phase Change Diagram