Alkene and double bond?

Question

Why Alkene has double bond but alkane has single bond? Tell me reasons.

Answer 1

Quite simply, because we define it that way. Alkenes are molecules with at least one carbon-carbon double bonds, and alkenes are molecules with exclusively carbon-carbon single bonds.

If you are interested in the electronic structure that differentiates single and double bond you can check out molecular orbital theory in any chemistry text, or perhaps check out the wiki article for alkane / alkene /alkyne.

Answer 2

These are just different nomenclature classifications. Alkanes have only single bonds and alkenes contain carbon to carbon double bonds. A simple way of thinking of the formulas is that alkanes are CnH(2n+2) while hydrocarbons containing 1 C=C will be CnH2n. The difficulty here is that compounds containing a "ring" will also be CnH2n.

Answer 3

When naming hydrocarbons, alkanes havae single bonds, by definition, alkenes have one double bond between carbons, and alkynes havae one triple bond, by definition. There can be molecules with more than one double bond or more than one triple bond., named differently.

Answer 4

That is simply due to naming. Single bonded hydrocarbons are called alkanes while double bonded hydrocarbons are called alkenes. (FYI: triple bonded hydrocarbons are called alkynes)