Recording-2025-02-24T21:38:10.558Z

Elements of Life

• Definition: Elements are pure substances that cannot be broken down into simpler substances by chemical means.

• Key Elements: Four primary elements—Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N)—are fundamental for life.

  • These elements are the building blocks for biological molecules:

    • Carbohydrates: Serve as energy sources and structural components.

    • Proteins: Function in catalysis, structure, signaling, and transport.

    • Lipids: Store energy and make up cell membranes.

    • Nucleic Acids: Carry genetic information.

• Trace Elements: Essential in minute amounts (e.g., Iron (Fe), Iodine (I), Copper (Cu)). Important for various biological functions.

Subatomic Particles

• Atom Structure: Atoms are the basic unit of matter.

  • Protons: Positively charged (+) particles located in the nucleus.

  • Neutrons: Neutral particles that also reside in the nucleus.

  • Electrons: Negatively charged (–) particles that orbit the nucleus.

• Isotopes: Atoms of the same element with different numbers of neutrons. These isotopes can have varying stability and radioactive properties.

Compounds and Bonds

• Definition of Compounds: Substances formed when two or more elements chemically combine.

• Chemical Bonds:

  • Ionic Bonds: Formed when one atom transfers electrons to another, resulting in charged ions that attract each other.

  • Covalent Bonds: Occur when atoms share electrons.

    • Non-polar Covalent Bonds: Electrons are shared equally between atoms.

    • Polar Covalent Bonds: Electrons are shared unequally, leading to partial charges.

Water: The Versatile Molecule

• Hydrogen Bonds: Weak bonds that form between hydrogen atoms in a molecule and electronegative atoms (like oxygen in water).

• Special Properties of Water:

  • Cohesion: Water molecules have a strong tendency to stick to each other, which results in high surface tension.

  • Adhesion: Water can adhere to other substances, aiding in processes such as capillary action in plants.

  • High Heat Capacity: Water can absorb and retain heat, stabilizing environmental temperatures.

  • Expansion on Freezing: Ice is less dense than liquid water, causing it to float, which is essential for aquatic ecosystems.