British Sign Language Glossaries of Curriculum Terms

BSL Chemistry Glossary - alkane - Definition

Alkanes are a group of hydrocarbons that only contain hydrogen and carbon and no other elements - just C and H.

Alkanes only have single bonds (no double bonds). Here is the list that makes up the group; as you go down the number of carbons in each molecule increases from one at the top, then two (you can see one more added there); to three, then four, five, six, seven and eight. You need to remember the names as we run down the list.

The first one is called methane, next is ethane, then propane. These names relate to the number of carbons - methane has one carbon, ethane two, propane three, butane will have 4 carbons.

Each of these names ends in -ane which means it has a single bond (not to be confused with Alkenes which have a double bond). These compounds can be written out in different ways, either like this, or on the far right, using the full structural formula which you will see is just made up of Cs and Hs.

If you need to work out the number of carbons and hydrogen atoms in any of these there's a general formula and that's it here (points) Cn H₂n+2 and this applies to Alkanes only.

If we take butane for example, if we look at our list we see it has 4 carbons, then if we want to know how many hydrogen atoms there are it's 2x4 = 8+2 = 10. Therefore the chemical formula for butane is C₄H₁₀.

The last thing to mention is that all Alkanes have similar chemical properties.