Butane:C4H10 CH3CH2CH2CH3 n-butane CH3 CH3CHCH3 iso-butane Constitutional isomers are compounds with the same molecular formula but the carbons are connected differently. Chapter 3 6 Chapter 3 6 Butane: C4H10 Constitutional isomers are compounds with the same molecular formula but the carbons are connected differently. CH3CH2CH2CH3 n-butane CH3CHCH3 iso-butane CH3