Chemistry of Life - Concept 2 Notes

Chemistry of Life - Concept 2 Notes

• Matter is anything that has mass and occupies space
• Matter is composed of the smallest part of an element, which still retains the properties of that element. This is called an atom.
• Six elements are essential for life: C, H, O, N, P, & S.
• The cell is the fundamental unit of life.

Water

• Water (H₂O) is a molecule made of two hydrogen atoms covalently bonded to one oxygen atom.
• Water is critical for all life processes.
• It has special properties mostly due to its polar molecule structure.

Polar and Nonpolar Molecules

• Polar molecules have an unequal distribution of charges, one side more positive and the other more negative. Polar molecules dissolve in water.
  • Water is an example of a polar molecule.
• Nonpolar molecules have no separation of charges. They do not dissolve in water.
  • Examples include CO₂, O₂, and lipids.

Properties of Water

• Cohesion: The attraction between molecules of the same substance (e.g., water sticking to water). This creates surface tension.
• Adhesion: The attraction between molecules of different substances (e.g., water sticking to glass).
• High specific heat: Water resists temperature changes. It takes more energy to raise the temperature of water compared to other substances. This helps regulate cell temperatures in organisms and Earth's climate.
• Less dense as a solid: Ice (solid water) is less dense than liquid water and floats. This is crucial for aquatic life in winter.
• Universal solvent: Water dissolves a large number of substances. This is due to its polarity.

Cohesion

• Cohesion is the attraction between water molecules.
• Water molecules stick together.
• Surface tension is related to cohesion

Adhesion

• Adhesion is the attraction between water and other substances.
• Water sticks to other surfaces.
• Capillary action is related to adhesion

High Specific Heat

• Water resists changes in temperature.
• It needs more heat to raise its temperature than many other substances.
• This property helps moderate temperatures in organisms and on Earth.

Less Dense as a Solid

• Ice, the solid form of water, is less dense than liquid water.
• Ice floats, which insulates bodies of water and allows aquatic life to survive in winter.

Water as a solvent

• A mixture of two or more substances is called a solution.
• The substance being dissolved is called the solute.
• The substance that dissolves the solute is called the solvent.
  • Water is the universal solvent because it can dissolve a wide range of substances.

Hydrophilic and Hydrophobic Substances

• Hydrophilic substances have an affinity for water ("water-loving"). They typically dissolve in water.
  • Examples are salt and sugar.
• Hydrophobic substances do not have an affinity for water ("water-fearing"). They typically do not dissolve in water.
  • Examples are oils.

Explore the fundamental concepts of matter, atoms, and water in this quiz based on the chemistry of life. Learn about polar and nonpolar molecules, and discover the essential properties of water that sustain all life processes. Test your understanding of these concepts and their significance in biological systems.