Chemistry

This is killing my brain cells.

Amphetamine:

C9H13N
Mol. Mass: 135.2084

Dextroamphetamine:

C9H13N
Mol. Mass: 135.2062

They have the same formula, the same structure, but different Mol. Masses and different chemical properties. How?!

If you've read your lessons on isomers, just take a gander at them and you'll understand why. Mostly, it's to do with the molecular structure's change, strength of bonds between molecules, etc. responsible for altered mol. weights.

As to the chemical properties, stereo isomerism changes the entire 3-D structure of a molecule, which basically gives it different reactive properties. This is a simple explanation, basically nutshell style, so take coal and diamonds as sort of an example. Refer to your lessons for a more detailed bit though.

We aren't covering it. Chemistry Honors in High School and I'm still confuzzled... They have the same 3D model though, no?

here, just take an example model and flip it over 180 degrees, and you have your stereo isomer structure for any compound that applies for the same.