Properties of Matter and Phase Changes

Vocabulary practice cards covering the physical properties of matter, atomic definitions, phase changes, and historical atomic theories.

Solids

A state of matter characterized by a fixed shape, fixed volume, high density, and the inability to flow or be compressed significantly.

Liquids

A state of matter with a fixed volume but no fixed shape, moderate to high density, and the ability to flow.

Gases

A state of matter with neither a fixed shape nor a fixed volume that can be compressed easily, has very low density, and flows easily to fill its container completely.

Particles of Matter

Tiny pieces (atoms, ions, or molecules) that are very small, have spaces between them, move constantly, and attract each other.

Melting

A phase change from a solid to a liquid where heat is required.

Freezing

A phase change from a liquid to a solid where heat is generated.

Condensation

A phase change from a gas to a liquid where heat is generated.

Evaporation (vaporization)

A phase change from a liquid to a gas where heat is required.

Sublimation

A phase change from a solid directly to a gas where heat is required.

Deposition

A phase change from a gas directly to a solid where heat is generated.

Angstrom

A unit of length used to measure the size of an atom, equal to one ten millionth of a millimeter ($10^{-7}\,mm$).

Scanning Tunneling Microscope (STM)

An instrument that can magnify an image 10 million times and create a surface profile of an atom to produce a computer-generated model or contour map.

Atom

The smallest particle of an element that retains all properties of that element.

Molecule

A neutral particle consisting of two or more atoms that are chemically bonded together.

Ion

A particle that carries either a positive or negative charge.

John Dalton (1766-1844)

A scientist whose theory states that all matter is made of individual, indivisible particles called atoms.

Democritus (460 B.C. - 370 B.C.)

An ancient Greek philosopher who proposed that all matter is composed of indivisible and indestructible atoms in a void, which differ in shape, arrangement, and size.