In a gas, the molecules are not linked together with other gas molecules. They collide, but they don't form cluster.In a liquid, the individual molecules form small chains. These chains cluster...
water
Water is a gas when it is steam. It condenses to liquid, becoming water. It becomes solid when it freezes, and then becomes liquid again as it melts. The entire process depends on temperature....
All liquids can also be solids and gases including Helium in special conditions. However, there are two liquid elements Bromine and Mercury. These also can be solid liquid and gaseous.