Question

What properties does a gas have in terms of shape and volume

Answer 1

Gases, liquids and solids are all made up of atoms, molecules, and/or ions, but the behaviors of these particles differ in the three phases. The following figure illustrates the microscopic differences.

Microscopic view of a gas Microscopic view of a liquid. Microscopic view of a solid.
Microscopic view of a gas. Microscopic view of a liquid. Microscopic view of a solid.
Note that:

Particles in a:
gas are well separated with no regular arrangement.
liquid are close together with no regular arrangement.
solid are tightly packed, usually in a regular pattern.
Particles in a:
gas vibrate and move freely at high speeds.
liquid vibrate, move about, and slide past each other.
solid vibrate (jiggle) but generally do not move from place to place.
Liquids and solids are often referred to as condensed phases because the particles are very close together.
The following table summarizes properties of gases, liquids, and solids and identifies the microscopic behavior responsible for each property.