Notes on Carbon & Organic Compounds - Chapter 2.3

Organic Chemistry

• Organic chemistry is the study of compounds that contain carbon, regardless of origin.
• Organic compounds range from simple molecules to colossal ones.
• Because carbon can form four bonds, these building blocks can be used to make an inexhaustible variety of organic molecules.
• The great diversity of organisms on the planet is due to the versatility of carbon.

Carbon

• Carbon contains carbon in organic molecules; organic molecules are abundant in living organisms.
• Carbon has $4$ electrons in its outer shell, so it can form up to $4$ covalent bonds.
• Carbon forms only covalent bonds.
• Carbon can form polar or nonpolar bonds.
• Hydrocarbons are nonpolar; they have only C–C and C–H bonds; they are hydrophobic and poorly soluble in water.
• Oxygen and nitrogen form polar bonds with carbon; these bonds tend to be hydrophilic and increase solubility in water.

Hydrocarbons

• Hydrocarbons are organic molecules consisting of only carbon and hydrogen.
• Many organic molecules, such as fats, have hydrocarbon components.
• Hydrocarbons can undergo reactions that release a large amount of energy.

Isomers

• Isomers are compounds with the same molecular formula but different structures and properties.
• Structural isomers have different covalent arrangements of their atoms.
• Cis-trans isomers (also called geometric isomers) have the same covalent bonds but differ in their spatial arrangements.
• Enantiomers are isomers that are mirror images of each other.

Chemical Groups

• Distinctive properties of organic molecules depend on the carbon skeleton and the chemical groups attached to it.
• These groups help give each molecule its unique properties.
• Example: Estradiol and testosterone are both steroids with a common carbon skeleton in the form of four fused rings.

Functional Groups

• Functional groups are the components of organic molecules that are most commonly involved in chemical reactions.
• The number and arrangement of functional groups give each molecule its unique properties.
• Example: the amino group $\mathrm{-NH_2}$ acts as a base.

Functional Groups (Seven Major Groups)

• The seven functional groups that are most important in the chemistry of life are the following:
  • Hydroxyl group
  • Carbonyl group
  • Carboxyl group
  • Amino group
  • Sulfhydryl group
  • Phosphate group
  • Methyl group

The Chemical Elements of Life: A Review

• The versatility of carbon makes possible the great diversity of organic molecules.
• Variation at the molecular level lies at the foundation of all biological diversity on our planet.