B1.1.1 Chemical properties of a carbon atom Notes

Why Is Carbon So Essential?

1. From the DNA in your cells to the food you eat, carbon forms the foundation of all biological molecules, enabling the complexity of life as we know it.
2. But why is it the element of life, rather than something more common, like oxygen or nitrogen?

The answer lies in its bonding abilities, versatility, and role in molecular diversity.

Covalent Bonding: The Key to Stability

1. A covalent bond forms when two atoms share a pair of electrons. Carbon is exceptional because:
   1. Stability: Covalent bonds are the strongest type of bonds in biological systems, perfect for creating durable molecules like DNA and proteins.
   2. Electron Configuration: Carbon has four electrons in its outer shell but needs eight for stability.
   3. This allows it to form four covalent bonds, giving rise to complex structures.

Carbon’s Bonding Potential: The Foundation of Molecular Diversity

Carbon can form a variety of structures, ranging from simple chains to complex rings, making life’s molecular diversity possible.

1. Single Bonds: Creating Long Chains
   1. Straight chains (e.g., fatty acids in cell membranes).
   2. Branched chains (e.g., isobutane, which affects molecular interactions and function).
2. Double and Triple Bonds: Adding Rigidity and Reactivity
   1. Double bonds introduce kinks in molecules (e.g., unsaturated fatty acids, which impact membrane fluidity).
   2. Triple bonds (less common but extremely strong) alter molecular properties.
3. Carbon Rings: The Basis of Life’s Chemistry
   1. Single Ring (e.g., glucose): Soluble, making it ideal for energy transport in the body.
   2. Multiple Rings (e.g., cholesterol): Strengthens cell membranes and serves as a precursor for hormones.

Functional Groups: The Source of Chemical Diversity

While the carbon backbone provides structure, functional groups determine a molecule’s reactivity and interactions.