Question

what happens to the atoms and molecules as you add heat?

Explanation:

Step1: Understand heat energy

Heat is a form of energy. When heat is added to a substance, the atoms and molecules gain energy.

Step2: Analyze molecular motion

According to the kinetic - molecular theory, atoms and molecules are in constant motion. With added heat, their kinetic energy increases.
$$\text{Kinetic Energy}=\frac{1}{2}mv^{2}$$
where \(m\) is the mass of the particle and \(v\) is its velocity. As heat (energy) is added, \(v\) (velocity) increases.

Step3: Determine the effect on arrangement

In solids, atoms/molecules vibrate more vigorously around their fixed positions. In liquids, they move more freely and faster. In gases, the already fast - moving atoms/molecules move even faster and spread out more if there is space.

Answer:

As heat is added, the atoms and molecules gain kinetic energy. Their motion (vibration in solids, translation in liquids and gases) becomes more vigorous. In solids, they vibrate more around their lattice points. In liquids, the molecules move faster and can overcome more intermolecular forces to some extent. In gases, the atoms/molecules move faster and, if in a non - rigid container, can expand.