Study Notes
Water molecules are polar and form hydrogen bonds with each other, giving water unique properties such as cohesion, adhesion, and solvent capabilities. These properties are crucial for biological processes and the transport of substances in organisms.
- Polar covalent bond — A type of chemical bond where electrons are unequally shared between atoms. Example: The bond between hydrogen and oxygen in a water molecule.
- Cohesion — The ability of like molecules to stick together. Example: Water molecules forming hydrogen bonds with each other.
- Adhesion — The ability of dissimilar molecules to stick together. Example: Water molecules sticking to glass surfaces.
- Thermal properties — Water's ability to absorb and retain heat. Example: Water's high specific heat capacity stabilizes temperatures in aquatic environments.
- Solvent properties — Water's ability to dissolve polar and ionic substances. Example: Sodium chloride dissolving in water to form ions.
- Hydrophilic — Substances that are attracted to water and dissolve in it. Example: Glucose and sodium ions.
- Hydrophobic — Substances that repel water and do not dissolve in it. Example: Fats and oils.
Exam Tips
Key Definitions to Remember
- Polar covalent bond
- Cohesion
- Adhesion
- Hydrophilic
- Hydrophobic
Common Confusions
- Mixing up cohesion and adhesion
- Confusing hydrophilic with hydrophobic substances
Typical Exam Questions
- What is cohesion? The ability of like molecules to stick together, such as water molecules forming hydrogen bonds.
- How does water's high specific heat capacity benefit living organisms? It stabilizes temperatures in aquatic environments, providing a stable habitat.
- Why is water considered a good solvent? Because it can dissolve polar and ionic substances due to its polar nature.
What Examiners Usually Test
- Understanding of water's unique properties due to hydrogen bonding
- Ability to explain the significance of water's thermal and solvent properties in biological contexts