Teacher resources and professional development across the curriculum

Teacher professional development and classroom resources across the curriculum

# Unit 2: The Behavior of Atoms—Phases of Matter and the Properties of Gases

## Glossary

Atmospheric pressure
The force exerted by the weight of the atmosphere on a given unit area. Atmospheric pressure on Earth at sea level is 14.7 pounds per square inch (psi), 760 torr or 1 atm.
Critical point
The combination of temperature and pressure beyond which a gas becomes a supercritical fluid.
Deposition
A process by which matter can turn from a gas directly into a solid.
Directly proportional
Occurs if, as the value of one variable increases, the value of another variable increases at the same rate.
Gas
A low-density phase of matter that has no shape or volume, and will fill the entire volume of a container.
Liquid
A phase of matter that has a distinct volume but no shape.
Newton
The absolute unit of force in the International System of Units (SI units). The newton is defined as the force necessary to provide a mass of one kilogram with an acceleration of one meter per second. It was named for Sir Isaac Newton (1642–1727), the British physicist, whose Second Law of Motion describes the changes that a force can produce in the motion of a body.
Phase change
The conversion of a substance from one state to another. Phase changes include melting (solid to liquid), freezing (liquid to solid), vaporization (liquid to gas), condensation (gas to liquid), sublimation (solid to gas), and deposition (gas to solid).
Solid
A phase of matter that has a distinct volume and shape.
Triple point
The combination of temperature and pressure at which a substance can exist as a solid, a liquid, and a gas simultaneously.