Drawing Structual formulas?

Question

How do I know when to use single, double or triple bonds?

Please explain in very basic terms as chemistry is all new to me.

cheers

Answer 1

The easiest way to remember it is that carbon always wants to have 4 bonds, and hydrogen onlywants 1 bond.  Take C2H6, C2H4 and C2H2.  In order for carbon to have it's 4 bonds, C2H6 will have to only have single bonds, one bond per hydrogen and one bond linking the two carbons.  With C2H4 in order for carbon to have four bonds and each hydrogen one bond you will have 2 single bonded hydrogen's to each carbon and a double bond between the 2 carbons.  With C2H2, each hydrogen will have 1 bond between it and the carbon so in order for each carbon to have its required 4 bonds, they will need to be triple bonded to each other.

Answer 2

If only 2 electrons are shared i.e. 1 by each then a single bond is formed,if 4 electrons are shared i.e. 2 by each then

double bond is formed and when 6 electrons are shared i.e. 3 by each then triple bond is formed

Answer 3

For instance..

Hydrocarbons that contain a carbon-carbon double bond are known as alkenes. The simplest alkene is ethene,C2H4

We derived the IUPAC name of an alkene from the "parent" alkane bearing the same number of carbons by replacing the  -ane suffix with  -ene.Thus,

ethane(with a single bond) becomes ethene(with a double bond)

Alkynes are hydrocarbons that contain a carbon-carbon triple bond. The simplest alkyne is ethene, C2H2. We replace the  -ane suffix with -yne.

Thus,

ethane(having single bond) becomes ethyne(having triple bonds)..

hope it helps..