Unit 10 Topic 1- Chemistry

Organic Chemistry

Organic Molecules

• Organic molecules must contain both carbon and hydrogen.
  • Example: $CH<em>4$ vs. $CO</em>2$
• Organic molecules may contain other elements.
• A hydrocarbon is an organic molecule that contains only carbon and hydrogen.
  • Example: $C<em>2H</em>6$ vs. $C<em>2H</em>5COOH$

Properties of Organic Compounds

• Many organic compounds share similar properties:
  • Most are non-polar molecules (symmetrical with H on every side).
    • This causes most of them to be insoluble in water.
    • This also causes most of them to have low melting points due to weak intermolecular forces; as only Van der Waals forces are present.
  • They are nonelectrolytes (they don’t dissociate & conduct electricity; organic acids are an exception).
  • They are involved in slow chemical reactions.
  • Organic molecules tend to have more/stronger bonds than ionic compounds.
  • Organic molecules are often large and complex.
    • Since carbon has 4 valence electrons, it can form 4 covalent bonds, more than most other elements.
    • Carbon is considered to be the “skeleton” of organic molecules.
    • Chains or rings of carbons bonded to other carbons are often formed.
  • Organic molecules make up over 65% of Earth’s molecules.

Isomers

• Isomers are molecules with the same molecular formula but different structural formulas.
• More carbons present results in more possible isomers.
• Isomers are NOT the same molecule just bent in a new way.
  • Check that the molecular formulas match.
  • Next, check that the structures differ in some way (you can use the Finger-Tracing method).
• Examples of isomers:
  • Butane and 2-methyl propane.
  • Propanal and Propanone.

Isomer Examples

• Example 1: Distinguishing isomers by comparing structural formulas.
• Example 2: Given different structural formulas, identify which two represent compounds that are isomers of each other.