## Molecular Formula and Chemical Structure

Michelle_Nguyen_3F
Posts: 40
Joined: Wed Sep 21, 2016 2:59 pm

### Molecular Formula and Chemical Structure

Hello!

I know that alkanes have the general molecular formula: $C_{n}H_{2n+2}$ and that any compound with this carbon and hydrogen ration must be an alkane. In the course reader, it asks if we are able to determine the structure from the molecular formula. It then says we do not know the structure from the molecular formula if there are 4 or more carbons. Why is this the case? Thank you!

mikezargari
Posts: 20
Joined: Wed Sep 21, 2016 2:56 pm
Been upvoted: 1 time

### Re: Molecular Formula and Chemical Structure

When dealing with molecules that have four or less carbons the chemical structure can only be unbranched in order to accommodate all carbons and hydrogens in the molecule. When a molecule contains 5 or more carbons the molecule's structure can begin to take various forms. Each of these forms are equally valid structures, which prevents us from being able to know which one the molecular formula is intending to represent. Hope this helped.