B1.1.1 — Chemical Properties of Carbon and Its Role in Biological Molecules

1. Chemical Properties of Carbon

Bonding Ability of Carbon

• Atomic Number: 6 → Carbon has 4 electrons in its outer (valence) shell.
• Needs 4 more electrons to complete its octet → can form 4 covalent bonds with other atoms.
• This allows for diverse molecular structures:
  • Single, double, or triple bonds
  • Chains (branched or unbranched)
  • Rings (single or fused)
  • Large, complex molecules like macromolecules

Types of Atoms Carbon Can Bond With

• Carbon (C)
• Hydrogen (H)
• Oxygen (O)
• Nitrogen (N)
• Sulfur (S)
• Phosphorus (P)

2. Covalent Bonds: Cause and Consequence

Definition of Covalent Bond

• A covalent bond is a strong chemical bond formed when two atoms share one or more pairs of electrons.

Cause

• Atoms share electrons to achieve a full outer shell (more stable configuration).
• In carbon, this means forming four covalent bonds to achieve a full valence shell of 8 electrons.