1. Compounds
An atomic bond is a force which joins atoms together to form a molecule H O
Atomic bond
Water H

2. How Atomic Bonds Work Electrons are responsible for atomic bonding.
There are 3 ways electrons can interact to form bonds

3. Ionic Bonds: STRONG
An atom loses 1 or more electrons, giving it a positive charge.
Another atom gains the electron(s) and becomes negatively charged
+ & - ions attract. - + e- e- Cl e- Na e- e- e- e- e-

4. Covalent bonds: STRONG
2 atoms share a pair of electrons H H e- e-

5. Polar Covalent Bonds: STRONG
In a polar bond, electrons are shared unevenly.
Since electrons are negative, the atom that attracts electrons the most becomes a little negative, and the atom losing the electrons becomes a little positive.

6. Water is Special
Property #1: Water resists changes in temperature & phase
Demonstration
High “Specific Heat Capacity”
Related Property: high melting & boiling points

7. Related: High Melting & Boiling Points

8. Property 2: High Surface Tension, etc.
Water’s high surface tension causes:
Adhesion:
Water sticking to other surfaces
“Capillarity”
Cohesion:
Water sticking to Water

9. Property #3: Excellent Solvent
Water is very good at dissolving substances, particularly polar or ionic ones.
“Universal Solvent”

10. Property #4: Density Anomaly
Ice floats on water!
Water is one of the only compounds known that gets less dense when it freezes!

11. Water is a polar molecule. The O-H bonds are polar covalent
Molecules with positive and negative parts are called polar molecules.
Polar molecules can form hydrogen bonds

12. New Bond - Hydrogen Bond: Pathetically WEAK!
A Hydrogen bond is a weak bond between 2 electrical poles (usually different molecules)

13. WHY WATER HAS SPECIAL PROPERTIES
Water has all of those weird properties happen because of 1 simple thing…
HYDROGEN BONDS

14. Water is a polar molecule
It has a positive and negative side, causing hydrogen bonds

16. How H-bonds Give Water it’s Special Properties
Property
How H-Bonds Make it Happen
Temperature & Phase Stability
Energy is required to break H-bonds, reducing the amount of energy for T increase or phase change
Surface Tension, etc.
Can form H-bonds with itself or other substances, making it “sticky”
Solvent
Areas of charge arrange around charged parts of molecules
Density Anomaly
H-bond length increases as temperature drops from 4oC to 0oC