Organic compounds have low melting points, non-electrolytes and form chains in straight lines, circular patterns or branched patterns. These can be linked up in single, double or triple bonds.
Alkanes are saturated hydrocarbons where all the bonds are single bonds. Each carbon atom forms four bonds and each hydrogen forms a single bond to a carbon. The bonds are tetrahedral which form an angle of 109.5 deg.
| Selected Properties of the First 10 Normal Alkanes | |||||
| Name | Formula | Molar Masses | Melting Point (°C) | Boiling Point (°C) | Number of Structural Isomers |
| Methane | CH4 | 16 | –183 | –162 | 1 |
| Ethane | C2H6 | 30 | –183 | –89 | 1 |
| Propane | C3H8 | 44 | –187 | –42 | 1 |
| Butane | C4H10 | 58 | –138 | 0 | 2 |
| Pentane | C5H12 | 72 | –130 | 36 | 3 |
| Hexane | C6H14 | 86 | –95 | 68 | 5 |
| Heptane | C7H16 | 100 | –91 | 98 | 9 |
| Octane | C8H18 | 114 | –57 | 126 | 18 |
| Nonane | C9H20 | 128 | –54 | 151 | 35 |
| Decane | C10H22 | 142 | –30 | 174 | 75 |
Formula for writing alkanes: CnH2n+2. Where n = number of carbon atoms.
Hydrocarbons can also have side branches. Branched hydrocarbons are hydrocarbon molecules where the carbon atoms are not arranged in a simple chain, but are arranged in a network of multiple chains.
Naming branched hydrocarbons
| Substituent Formula | Number of C Atoms | Name of Substituent |
|---|---|---|
| CH3 | 1 | methyl- |
| CH3CH2 | 2 | ethyl- |
| CH3CH2CH2 | 3 | propyl- |
| CH3CH2CH2CH2 | 4 | butyl- |
| CH3CH2CH2CH2CH2 | 5 | pentyl- |
- Find and name the longest continuous carbon chain and place it at the end of the name.
- Identify and name the groups attached to the chain
- Number the chain, starting at the side nearest to the side group
- Designate the location of each side group by an appropriate number and name
- Assemble the name, listing groups in alphabetical order.
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