4. Summary and Vocabulary

Summary

  • States of matter are different phases in which any given type of matter can exist. There are four well-known states of matter—solid, liquid, gas, and plasma—but only the first three states are common on Earth.
  • State of matter is a physical property of matter. A given kind of matter has the same chemical makeup and the same chemical properties, regardless of state.
  • Solids have a fixed volume and a fixed shape. Liquids have a fixed volume but take the shape of their container. Gases take both the volume and the shape of their container.
  • According to the kinetic theory, particles of matter are in constant motion. The energy of motion is called kinetic energy.
  • The kinetic energy of particles of matter determines the state of matter. Particles of solids have the least kinetic energy and particles of gases have the most.
  • A liquid is a state of matter in which particles can slip past one another and take the shape of their container. However, the particles cannot pull apart and spread out to take the volume of their container.
  • A solid is a state of matter in which particles of matter are tightly packed together. This holds the particles rigidly in place and gives solids a fixed shape and fixed volume.
  • Gas is a state of matter in which particles of matter can pull apart from each other and spread out. As a result, a gas does not have a fixed shape or a fixed volume.
  • Gas particles are constantly moving and bumping into things, and this creates force. The amount of force pushing against a given area is called pressure.

Vocabulary

  • state of matter: Different phase (solid, liquid, gas, and plasma) in which matter can exist without the chemical makeup of matter changing.
  • kinetic theory of matter: Theory that all matter consists of constantly moving particles.
  • liquid: State of matter that has a fixed volume but not a fixed shape.
  • solid: State of matter that has a fixed volume and fixed shape.
  • gas: State of matter that has neither a fixed volume nor a fixed shape.
  • plasma: State of matter that has no fixed shape or volume that contains ions. It responds to magnetism and conducts electricity. 

CK-12 Foundation, Physical Science. http://creativecommons.org/licenses/by-nc-sa/3.0/