1. Thermal Properties
Of water

2. Phase changes of water and energy
When water is in its liquid form, it is capable of absorbing high amounts of energy without changing phase
Water molecules in liquid phase interact with each by forming Hydrogen bonds-but individual bonds only last for a few moments
As long as water molecules are free to move, they will do so

3. Removing energy from a system
When energy is removed, speed of particles decrease
This results in water molecules forming more long-term Hydrogen Bonds to other water molecules
Because the electrons in orbitals are mutually-repelling, and the spatial arrangement of these bonds is tetrahedral, water forms highly-ordered crystal structures when in a low energy state

4. Ice

5. Ice and Density Ice is less dense than liquid water
This is because the Hydrogen bonds that form between molecules in ice hold the individual molecules from each other at a distance that is greater than they’d be at in liquid phase
So ice floats (anything less dense than water floats on water—duh!)

7. Adding energy to the system
Increasing the free-energy level in a system causes the particles within the system to move with faster and faster velocities
In this case, water molecules begin moving too quickly to interact with each other
As they move faster and faster, the total number of molecules occupies more space
Steam, clouds, fog, your breath on a cold day are water molecules in gas phase

8. Review-bonding and energy
High energy water molecules exist as steam. They release that energy by forming bonds with other water molecules
Water in liquid phase transitions to solid phase as energy is removed
Bond formation is energy releasing
Ice requires the input of energy to become a liquid
Water transitions to steam as more energy is put in
Bond breaking is energy consuming

9. Changes to energy and room to move

10. Heat capacity of water
It takes considerable energy to change the phase of water
This energy is measured in calories (the amount of energy it takes to raise one mL of water by 1 degree Celsius)
Because of this, sudden drops below freezing do not cause large bodies of water to freeze, for example
On a continental scale…

12. End of section