can CH3F, CH2Cl2, or XeCl2F2 have isomers?

Question

This is a question on my chem hw and i was just wondering how i would find out this answer. Can someone please explain what an isomer is and how it relates to these molecules? thanks

Answer 1

There are three types of isomers: structural isomers, geometric isomers and enantiomers.

Structural isomers are compounds which have their atoms and functional groups joined together in various ways, for example C3H8 can be made into quite a few differing compounds.

Geometric isomers usually are a result of double bonds. Because double bonds are inflexible, having an arrangement on one side makes the compound different than if that arrangement were on the other side of the double bond.

Enantiomers are simply compounds which are a mirror-image of each other.

In response to your question, CH3F and CH2Cl2 do not have isomers that I am aware of, because each structure is simply a central carbon with four atoms bound to it. XeCl2F2 I am not positive about because of the fact that Xe has several oxidation states, so it is possible that it can have an isomer.

Answer 2

Start at the beginning. Compound isomers have the same formula, but differ in structure. They have slightly different properties from other isomers. The compounds listed have what is called "sp3" molecular orbitals. The center atom (in the first two examples, carbon and the last, xenon) has four bonds, each of which is directed at the corner of a tetrehedral pyramid. This is a pyramid with a triangular base and 3 triangular sides as opposed to the Egyptian pyramids.
At each corner is an atom to which the center atom is bonded.

Such a compound could be an isomer if it could not, by simple moving or turning of the molecule, become identical to another molecule of the compound. This is easier to show in alkene compounds, where there is cis-trans isomers based on positions relative to the double-bonded carbons. In the examples you have, they don't have isomers. However, if you had a molecule like CH2ClBr, you would have two isometric forms. Just take some putty and eight toothpicks and try it out.