Overview
This lecture introduces hydrocarbons, focusing on alkanes, their structure, general formula, and key characteristics in organic chemistry.
Introduction to Organic Chemistry
- Organic chemistry studies compounds containing carbon.
- Carbon atoms can form four strong covalent bonds, often with hydrogen or other carbons.
Hydrocarbons
- Hydrocarbons are compounds made only of carbon and hydrogen atoms.
- Example: Butane (C4H10) is a hydrocarbon; butanol (which contains oxygen) is not.
Alkanes
- Alkanes are the simplest type of hydrocarbons.
- The first four alkanes are methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10).
- In alkanes, each subsequent molecule differs by one carbon and two hydrogens.
- Alkanes form a homologous series, meaning they have similar properties and reactions.
- The general formula for alkanes is CnH2n+2.
Calculating Molecular Formulas
- To find the formula, multiply the number of carbons (n) by two and add two for hydrogens.
- Example: Octane, with 8 carbons, has the formula C8H18.
Saturation in Alkanes
- Alkanes are saturated compounds; all carbon atoms have four single covalent bonds.
- No double bonds exist in alkanes.
- Introducing a double bond (by removing hydrogens) changes a molecule from an alkane to an alkene.
Key Terms & Definitions
- Organic Chemistry — study of carbon-containing compounds.
- Hydrocarbon — compound made of only hydrogen and carbon.
- Alkane — saturated hydrocarbon with single bonds, general formula CnH2n+2.
- Homologous Series — group of compounds with the same general formula and similar properties.
- Saturated Compound — molecule where all carbons have single bonds.
- Alkene — unsaturated hydrocarbon with at least one double bond.
Action Items / Next Steps
- Review the general alkane formula and practice calculating more molecular formulas.
- Prepare for the next lesson on the properties and combustion equations of alkanes.