Question

Name	Molecular formula	Condensed Structural formula	Number of carbon atoms	Number of -CH2 - units	Boiling point °C
Ethene	C2H4	\[\ce{CH2 = CH2}\]	2	0	−102
Propene	C3H6	\[\ce{CH3 - CH = CH2}\]	3	1	−48
1-Butene	C4H8	\[\ce{CH3 - CH2 - CH = CH2}\]	4	2	−6.5
1-Pentene	C5H10	\[\ce{CH3 - CH2 - CH2 - CH = CH2}\]	5	3	30

The above table shows the homologous series of alkenes. Inspect the molecular formulae of the members of this series. Do you find any relationship, in the number of carbon atoms and the number of hydrogen atoms in the molecular formulae?

Answer 1

If we look at the molecular formulas of alkenes in the mentioned homologous series, we can see that there are half as many carbon atoms as hydrogen atoms.