1. Notes Page 27 of Unit Folder
The Water Molecule
Notes
Page 27 of Unit Folder

2. Get to know H20 - 2 parts Hydrogen - 1 part Oxygen
- Hydrogens have a positive charge
- Oxygen has a negative charge

3. Covalent bonds
- Hydrogen and Oxygen connect with one another through a covalent bond. This means they share their electrons to make each atom have a full outermost shell and be stable (happy)

4. Polar Molecule
- Water is polar. This means it has a negative side and a positive side.
- All of the electrons (which have a negative charge) are gathered around the oxygen, so the oxygen side is negative.
- The hydrogen side is free of electrons, so it is positive.
- Oxygen is slightly negative, hydrogen is slightly positive.

5. Why does it matter?
- Because water has a positive end and a negative end, it is drawn to other water molecules.
- This means that water sticks together through weak positive-negative connections. These connections are called hydrogen bonds.
- It also means water sticks to other molecules and can pull them apart. This is why many things dissolve so easily in water – it is a universal solvent (a liquid things called solutes dissolve in)

6. Cohesion, adhesion, and Solubility
Cohesion – the ability of water molecules to stick to one another Ex. water in the glass
Adhesion – the ability of water molecules to stick to other molecules Ex. condensation on the glass
Solubility – the ability of water (or any other solvent) to dissolve another material (called a solute) Ex. sugar dissolved in the ice tea

7. Key Points: The Water Molecule
- Water is a covalent molecule made of two hydrogens and one oxygen sharing electrons.
- Because of the uneven distribution of the electrons, water molecules have a negative side and a positive side, making water a polar molecule.
- Polar molecules stick to one another through hydrogen bonding. When water sticks to itself, it is called cohesion.
- Polar molecules also pull apart other molecules. This is why salt, sugar, and other materials dissolve so well in water. Water is called a universal solvent.