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Polarity

The property of having distinct positive and negative charges in a molecule, like water, which affects its interactions with other molecules.

Hydration Shells

Layers of water molecules surrounding a solute particle, forming due to the polar nature of water.

Hydrophilic

Substances that readily dissolve in water; literally means 'water-loving'.

Hydrophobic

Substances that do not dissolve in water; literally means 'water-fearing'.

Cohesion

The attraction between molecules of the same substance, which in water leads to surface tension.

Adhesion

The attraction between molecules of different substances; in water, it allows water to 'climb' up surfaces like straws.

pH Scale

A measure of the acidity or basicity of a solution, ranging from 0 (very acidic) to 14 (very alkaline), with 7 being neutral.

Buffers

Substances that help maintain a stable pH in a biological system by absorbing excess H+ or OH- ions.

Acids

Substances that donate hydrogen ions (H+) in a solution, lowering the pH.

Bases

Substances that donate hydroxide ions (OH–) in a solution, raising the pH.

Solution

A homogeneous mixture of two or more substances, where one is dissolved in the other.

Solvent

The substance in a solution that dissolves the solute; in many cases, it is water.

Solute

The substance that is dissolved in a solution.

Osmosis

The movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Isotonic

A solution that has the same concentration of solutes as another solution, resulting in no net movement of water.

Hypertonic

A solution with a higher concentration of solutes compared to another solution, causing water to move out of cells.

Hypotonic

A solution with a lower concentration of solutes compared to another solution, causing water to move into cells.

Molarity

A way to express concentration, defined as the number of moles of solute per liter of solution.