If the particles of a liquid are always moving why dont they all come apart from each other and become gas?

Answer 1

Because they don't have enough energy to make the phase shift from liquid to gas. They don't have enough energy to break their INTERmolecular bonds enough to become a gas. They move around in what are called random walks and vibrate, just bumping into each other occasionally like you would people in a crowd. They don't have the energy to stat pushing and shoving violently enough to make the crowd separate far apart like you'd see in a mosh pit. Move space exists in a mosh pit than in a gentl crowd.

Answer 2

The particles in a liquid are constantly moving, but they are still held together by intermolecular forces. These forces are strong enough to keep the particles close together in a liquid state. As the temperature of a liquid increases, the particles move faster, eventually reaching a point where they break free from these forces and become a gas.