Why, in terms of atoms, are #CH_3CH_2OH# and #CH_3CHO# not isomers of each other?

1 Answer

Answer:

Because they don't follow the definition of an isomer

Explanation:

Here is the Oxford Dictionary definition of an isomer
"Each of two or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties."

#CH_3CH_2OH# has one more #O# and #H# than #CH_3CHO#

An example of an isomer is #C_4H_8#, as shown in this picture
www.chemguide.co.uk/organicprops/alkenes/background.html
It has the same amount of C and H atoms, but they're just arranged differently.