Lesson 5: States of matter: SOLID

• All matter is made of atoms or groups of atoms that are in constant motion. This idea is the basis for the kinetic theory of matter. 

A solid substance has a definite volume and shape. the particles in a solid are close together and do not move freely. Its particles vibrate but are fixed in place. 

Water is an importan excemption to this rule. The molecules that make up ice actually have more space between them than the molecules in liquid water do.