Chemistry for General Biology (Biology 1010)

Lecture Overview

• Basics of atomic structure and properties.
• Importance of water in biological processes.

Matter and Atoms

• Definition of Matter: Anything that takes up space and has mass.
• Elements: Substances that cannot be broken down, each with unique atomic structures.

Atomic Structure

• Components of an Atom:
  • Nucleus: Contains protons (positively charged) and neutrons (no charge).
  • Electrons: Negatively charged particles orbiting the nucleus.
• Example - Hydrogen: Only has one proton and one electron, no neutrons.
• Example - Oxygen: Has 8 protons, 8 neutrons, and 8 electrons.

Atomic Number & Mass

• Atomic Number: Number of protons, also indicates number of electrons in a neutral atom.
• Atomic Mass: Average weight of an element based on its isotopes.
• Protons: If the number changes, the element changes.

Ions and Isotopes

• Ions: Charged atoms formed by losing or gaining electrons.
  • Cations: Positively charged (loss of electrons).
  • Anions: Negatively charged (gain of electrons).
• Isotopes: Atoms of the same element with different numbers of neutrons.

Compounds and Emergent Properties

• Compounds: Combinations of two or more elements.
• Emergent Properties: New characteristics that arise when individual elements combine.
• Example - Table Salt (NaCl): Sodium is explosive in water, chlorine is a gas, but together they form a stable compound.

Electron Shells and Bonding

• Valence Shell: Outermost electron shell, important for bonding.
• Bonding Types:
  • Covalent Bonds: Sharing of electrons between atoms.
    • Strongest bond type.
  • Ionic Bonds: Attraction between oppositely charged ions.
    • Weaker than covalent bonds.
  • Hydrogen Bonds: Attraction between polar molecules.
    • Weaker than covalent and ionic bonds.

Properties of Water

• Polarity: Water is a polar molecule, leading to hydrogen bonding.
• High Specific Heat and Heat of Vaporization: Water can absorb significant energy without changing temperature significantly.
• Less Dense as a Solid: Ice floats on liquid water, essential for aquatic life in cold environments.
• Excellent Solvent: Can dissolve many substances due to its polarity.

Cohesion and Adhesion

• Cohesion: Water molecules attracting each other.
• Adhesion: Water molecules attracting to other substances.

pH Scale and Acids/Bases

• pH Scale: Measures acidity and basicity;
  • Acidic: pH < 7 (more hydrogen ions).
  • Basic: pH > 7 (more hydroxide ions).
  • Neutral: pH = 7 (equal hydrogen and hydroxide ions).
• Buffers: Solutions that resist changes in pH, crucial for maintaining homeostasis in biological systems.

Summary of Key Points

• All biological organisms are composed of elements that bond in various ways.
• Important properties of water contribute to its role in supporting life.
• Understanding atomic structure and electron dynamics is foundational for studying biochemistry.