Liquid Water
* Close Together: Water molecules are close together, held by weak hydrogen bonds.
* Limited Movement: They can move around, but their movement is restricted due to the close proximity and attraction.
* Vibrational Energy: Molecules vibrate and rotate.
Gas (Water Vapor)
* Far Apart: Water molecules are much farther apart than in liquid form. The hydrogen bonds are broken.
* High Energy: Molecules have significantly more kinetic energy (energy of motion). This is why it takes more heat to boil water than to melt ice.
* Free Movement: They move rapidly and randomly in all directions, colliding frequently with each other and with the walls of their container.
The Transition
When water transitions from liquid to gas (evaporation or boiling), the following happens:
1. Energy Input: Heat energy is added to the water molecules.
2. Increased Vibration: The molecules vibrate faster and break free from the hydrogen bonds holding them together.
3. Expansion: As the molecules gain energy, they spread further apart, occupying a much larger volume.
4. Phase Change: The liquid state changes to a gaseous state (water vapor).
Key Points:
* The transition is about a *change in the amount of energy* the water molecules possess, leading to a change in their movement and spacing.
* The more energy the molecules have, the faster they move and the further apart they are.
