| what is internal energy | the energy stored in a system by particles, the total kinetic and potential energy of all particles that make up a system |
| what happens when you heat a solid to a liquid | you are increasing the internal energy and causing the solid to melt into a liquid. particles gain energy and start to vibrate faster so the structure is gradually weakened , as more energy is given to the particles, they start to break free of the structure |
| what happens when you heat a liquid to a gas | you increase the internal energy causing the liquid to evaporate. particles are given more energy to move faster and collide with each other, most energetic particles at the surface escape from surface as water vapour, as more energy is given to particles, they will break free from the structure |
| what happens when a gas condensates into a liquid | the internal energy of the gas decreases so it condensates. as the particles lose heat, they lose energy and slow down, the particles collect together and form a liquid |
| what happens to a liquid when it freezes into a solid | the internal energy decreases and causes the liquid to freeze. energy is released from the liquid into its surroundings as particles lose heat therefore energy and become a solid |
| what is always conserves when changes of state occurs | mass |
| what is not called when a gas changes state directly to a solid | sublimation |
