what happens when solids, liquids, and gases are heated/cooled?

Most expand if heated; contract if cooled. Solids, if heated high enough will melt and the liquid may occupy less volume than the solid. Likewise, liquids, if heated high enough, will boil and the volume of the vapor will be larger than the volume of the liquid phase (under the same conditions of temperature and pressusre). Liquids, if cooled enough, may freeze and the solid formed MAY occupy more volume.

if a liquid is heated, it expands and becomes less dense.

When gasses are heated, it expands too

When solids, liquids, and gases are heated or cooled, they undergo changes in their physical properties and behavior. Here is a breakdown of what happens to each state of matter when they are subjected to changes in temperature:

Solids:
- When a solid is heated, its molecules begin to vibrate more vigorously, causing the solid to expand in size. This expansion is due to the increased kinetic energy of the molecules that make up the solid.
- As the temperature continues to rise, a solid may reach its melting point, which is the temperature at which it changes from a solid to a liquid. During melting, the arrangement of the solid's molecules becomes less ordered, and the solid becomes a liquid.
- If a solid is cooled, its molecules lose kinetic energy, which leads to a decrease in size. The solid contracts as the molecular motion slows down.

Liquids:
- When a liquid is heated, its molecules gain energy and move more rapidly. This increased molecular motion leads to an expansion of the liquid's volume.
- If the temperature of a liquid continues to rise, it may reach its boiling point. At this point, the liquid undergoes a phase change and transforms into a gas. During boiling, the intermolecular forces holding the liquid together are overcome by the increased molecular motion.
- When a liquid is cooled, its molecules lose energy and move more slowly. The decrease in molecular motion causes the liquid to contract and decrease in volume.

Gases:
- Heating a gas causes the average kinetic energy of its molecules to increase. As a result, the gas molecules move faster and occupy a larger volume. This expansion occurs because the gas particles are more spread out due to increased molecular motion.
- When a gas is cooled, its molecules lose energy and slow down. The decrease in kinetic energy causes the gas to contract in volume.

It is important to note that these generalizations may not always hold true for every substance. The behavior of solids, liquids, and gases when heated or cooled can vary depending on factors such as the specific substance, pressure, and the presence of impurities.