What is actually butane? Linear alkanes

You’ve probably used butane to cook at least once in your life or know someone who has. But what is actually butane?

Perhaps we should talk about alkanes first. An alkane is a compound consisting of hydrogen and carbon only (a hydrocarbon) with all its carbon atoms bonded to four other atoms (that is, saturated). The simplest alkanes have a linear structure. Their linear chain is formed by carbon atoms which are bond to as many hydrogen atoms as necessary to complete the four bonds.

Butane is an alkane with a four-carbon-atom chain. It can be represented:

butane (source)

Methane — main component of natural gas and which humans expel in farts — is an alkane with one only carbon atom.

The formulas of butane and methane are, respectively, CH₃−CH₂−CH₂−CH₃ (or C₄H₁₀) and CH₄. It’s not necessary to represent the bonds between carbon atoms, thus butane would be CH₃CH₂CH₂CH₃. Some observation reveals that the numbers of hydrogen atoms equals the double amount of carbon atoms plus two. Therefore, C_nH_{2n + 2} is the general formula for alkanes.

Alkanes are named with a prefix related to the number of carbon atoms in their chain and the ending for alkanes according to each language.

Nomenclature and formulas for some alkanes.

English	Catalan	Spanish	Portuguese	extended formula	general formula
alkane	alcà	alcano	alcano		CnH2n + 2
methane	metà	metano	metano	CH4	CH4
ethane	età	etano	etano	CH3CH3	C2H6
propane	propà	propano	propano	CH3CH2CH3	C3H8
butane	butà	butano	butano	CH3(CH2)2CH3	C4H10
pentane	pentà	pentano	pentano	CH3(CH2)3CH3	C5H12
hexane	hexà	hexano	hexano	CH3(CH2)4CH3	C6H14
heptane	heptà	heptano	heptano	CH3(CH2)5CH3	C7H16
octane	octà	octano	octano	CH3(CH2)6CH3	C8H18
nonane	nonà	nonano	nonano	CH3(CH2)7CH3	C9H20
decane	decà	decano	decano	CH3(CH2)8CH3	C10H22

The four first alkanes, from methane to butane, are gases at room temperature and atmospheric pressure. From pentane and to the 17-carbon-atom alkane (heptadecane), they are liquids, and they are solids over 18 carbon atoms at room temperature and atmospheric pressure.