How do solids and gases change state?

Under the right conditions, some solids and gases canc hange state without ever becoming aliquid. The sustance must gain or lose a great deal of energy for this to occur.

By sublimation

The change from a solid state directly into a gas is called sublimation. As the particles of solid dry, ice gain energy their motion completely overcomes the atraction between the particles, and the oarticles escape into the air as gas.

By deposition

Deposition is the change in state from a gas directly to a solid. Deposition is the process by which ice crystals form in clouds. When conditions are rightm depostion occurs when the particles of a gas lose energy. Atracttion between particles locks the particles into the rigid structure of a solid. No liquid is formed in the process.

What happens to matter when a change of state occurs?

When matter changes from one state to another, it remains the same kind of matter. Its physical state changes, but its chemical identity does not. 
The mass of a substance does not change when its state changes, Each state contains the same amount of matter.