Lecture Notes: The Atom and Its Components

Introduction to the Atom

• The smallest unit of matter.
• Comprised of subatomic particles.
• Subatomic particles define specific atoms (elements).
• Key regions include the nucleus and orbitals around the nucleus.

Subatomic Particles

• Protons
  • Positively charged.
  • Found in the nucleus.
  • Define the element (atomic number represents number of protons).
• Neutrons
  • Neutral charge.
  • Found in the nucleus.
  • Number can vary, leading to isotopes.
• Electrons
  • Negatively charged.
  • Found in orbitals around the nucleus.
  • Define chemical bonding.

Understanding Atomic Structure

• Atomic number = number of protons.
• Atomic mass = protons + neutrons.
• Neutrons = Atomic mass - Atomic number.
• Atoms are mostly neutral (equal number of protons and electrons).

Isotopes and Their Significance

• Isotopes differ in number of neutrons.
• Carbon Example
  • Carbon-12 vs. Carbon-14 (used in radiolabeling and dating).
• Radioactive isotopes can trace biological processes, e.g., glucose metabolism in the brain.

Importance of Elements in Biology

• Major Elements in Living Organisms
  • Hydrogen, Oxygen, Carbon, Nitrogen (96% of human body).
  • Carbon is a backbone for macromolecules.
  • Nitrogen is essential for proteins and nucleic acids.
• Trace Elements
  • Essential for various biological functions.
  • Examples: Calcium (bone health), Phosphorus (ATP), Sulfur (amino acids), Iodine (thyroid function), Manganese (antioxidant effects).

The Periodic Table

• Focus on the first three periods (C, O, H, P, S, N).
• Noble gases are inert (do not form chemical bonds).
• Reactivity patterns across periods and groups.

The Bohr Model of the Atom

• Represents electrons in orbitals around the nucleus.
• Electron Shells
  • First shell holds 2 electrons.
  • Second and third shells hold up to 8 electrons (Octet rule).
• Understanding shell filling and chemical bonding tendencies.

Key Patterns

• Rows in the periodic table share similar reactivity.
• Example: Hydrogen, Lithium, Sodium follow a pattern in electron configuration and reactivity.

Conclusion

• Overview of atomic structure and periodic table.
• Emphasis on protons, neutrons, electrons, and isotopes.
• Importance of elements and their roles in biological processes.