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

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

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)

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.

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)

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

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.