Chemistry: Bonding in Water Molecules

Study Notes

Hydrogen bonds are weak molecular forces that form between a positive hydrogen atom and a negative oxygen atom.
They are responsible for the cohesion and adhesion properties of water.

A diagram of a hydrogen bond would show a positive hydrogen atom bonded to a negative oxygen atom, with a dashed line representing the weak molecular force.

Cohesion: the bonding of two molecules of the same type, e.g., water molecules in a plant, allowing water to be transported from the roots to the top through hydrogen bonds.
Adhesion: the formation of hydrogen bonds between water and other polar molecules, causing water to stick to them, e.g., water evaporating from xylem vessels in plants and condensing on walls.
Latent heat of vaporization: the heat required for a molecule to evaporate and become vapor, e.g., the energy needed to boil water.
High boiling point: the highest temperature a liquid can sustain, e.g., water boils at 100°C.
High specific heat capacity: the amount of heat or energy water can absorb before the hydrogen bonds break, e.g., water's ability to maintain a cool temperature despite being heated.

Hydrophilic: a substance that is attracted to water, e.g., sugar, which absorbs water well.
Hydrophobic: a substance that repels water, e.g., oils, which cannot mix with water.