STATES OF MATTERCHAPTER 3

Matter and Energy

• Key Ideas

• What makes up matter?

• What is the difference between a solid, a liquid, and a gas?

• What kind of energy do all particles of matter have?

SECTION 3.1

Kinetic Theory

• Think about your favorite restaurant. Think about all the smells that you can smell.

• How is it that you can smell the food cooking even if you are a long way from the stove?

Kinetic Theory (cont’d)• We can make several assumptions as to why we

are able to smell the food cooking even if we’re not close to the stove.

• A collection of assumptions called kinetic theory allows for an explanation.

• Based on kinetic theory, we can assume that matter is made of atoms and molecules. These atoms act like tiny particles that are always in motion.

Kinetic Theory (cont’d)• The higher the temperature of the

substance is, the faster the particles move.

• At the same temperature, heavier particles move slower than lighter particles.

• Kinetic theory also allows us to understand the differences between the three most common states of matter: solid, liquid, and gas.

States of Matter• We can classify matter

according to shape and volume.

• The most commonly observed states of matter are solids, liquids, and gases.

• Each state has a distinct molecular makeup.

Solids

• Particles in a solid are in fixed positions. Each particle vibrates slightly.

• The particles cannot easily change position.

• Solids have definite shapes, as well as definite volumes.

Liquids• Particles in liquids are not as

tightly packed. The particles have room to glide past one another.

• Liquids are considered be fluids.

• Because of this ability to flow, liquids have no definite shape.

• Liquids have definite volume since the particles are close together.

Gases• Particles in a gas are very far

apart and can glide past one another.

• Gases are also considered to be fluids.

• Due to the distance between particles, gases have a constantly changing shape and volume.

Plasma• Scientists estimate that 99% of

the known matter in the universe, including the sun and other stars, is made of plasma.

• Plasma is a state of matter that has an indefinite volume and indefinite shape.

• Plasma is made up of charged atoms (ions).

• Examples: lightning, fire, the Northern lights

Energy’s Role• Energy is the ability to change

or move matter, or to do work.

• Energy exists in a variety of forms such as potential energy, kinetic energy, and thermal energy.

• According to the kinetic theory, all matter is in motion and must contain kinetic energy.

Temperature• Temperature is a

measurement of the average kinetic energy of the particles in an object.

• At lower temperatures, the particles of matter do not possess as much kinetic energy as particles at higher temperatures.

Thermal Energy• The temperature of a substance

is not determined by how much of the substance you have.

• Consider a teapot and a mug. The temperature of the tea in the teapot and mug are the same, but the total kinetic energy of particles in each are not.

• Thermal energy is the total kinetic energy of the particles that make up a substance.