Natura - nature actualia - actual entities Mundus Plinius - physical world naturalia - natural bodies "crystal-kingdom" chemical substances chemical compounds Class hydrocarbons [CxHy] - compounds consisting of carbon and hydrogen only Class alkanes [CnH2n+2] - saturated acyclic hydrocarbons branched alkanes 1.1 isobutane - C4H10 1.2 neopentane - C5H12 2 isopentane - C5H12 3.1 isohexane - C6H14 3.2 3-methylpentane - C6H14 3.3 2,2,4-trimethylpentane - C8H18