Why are alkenes and alkynes called unsaturated compounds?
Alkenes and alkynes are called unsaturated compounds because the carbon atoms that they contain are bonded to fewer hydrogen atoms than they can possibly hold.
Alkenes and alkynes are called unsaturated compounds because the carbon atoms do not have as many hydrogen atoms as they possibly could.
A saturated compound contains a chain of carbon atoms joined by single bonds, with hydrogen atoms filling all of the other bonding orbitals of the carbon atoms.
An example is butane, CH₃-CH₂-CH₂-CH₃.
It is saturated because every carbon holds as many hydrogen atoms as possible.
Alkenes such as but-2-ene (CH₃-CH=CH-CH₃) and alkynes such as but-2-yne, (CH₃-C≡C-CH₃) are unsaturated because the middle carbons contain fewer hydrogen atoms than they possibly could.