Study Notes on Properties of Water and Molecular Bonds

Molecules

• Definition: Subcomponents of biological molecules determine the properties of a molecule.

Properties of Water

• Water has a 1:2 ratio of oxygen to hydrogen atoms.

Types of Bonds

Covalent Bonds

• Definition: A covalent bond is the term used to describe the bond type in which atoms share electrons.

Hydrogen Bonds

• Definition: Weak bond interaction between the negative and positive regions of two separate molecules.

• Characteristics:
    - Cohesion:     - Definition: Similar molecules form hydrogen bonds with each other.
      - Example: Water on water exhibits cohesion.
    - Adhesion:
      - Definition: Different molecules form hydrogen bonds with each other.
      - Example: Water on glass exhibits adhesion.

Polarity

• Definition: Polarity occurs when there are differences in atomic electronegativities, resulting in an unequal sharing of electrons between atoms.

• Example in Water: Oxygen is more electronegative compared to hydrogen, leading to polarity in a water molecule.

Surface Tension

• Definition: Result of increased hydrogen bonding forces between water molecules at the surface.

• Example: Water on a penny forms a dome shape due to surface tension.

Solvency

• Description: Water has high solvency in its liquid state, though it is not the "universal solvent."

Density of Water

• Observation: Water as a solid (ice) is less dense than water as a liquid, which is why ice cubes float in water.

Heat Capacity

• Definition: Water has a high heat capacity, meaning it can absorb a lot of heat before it changes temperature significantly.

Capillary Action

• Definition: Water can climb up tubes due to cohesion and adhesion, demonstrating capillary action.