[Ticklezpanda]

Hi,

I am beginning to understand molecular orbital theory and I am able to develop the electronic configuration of molecules like O₂, B₂²⁺, etc. however I am unsure of how isotopes affect molecular configuration. Since neutrons carry no charge, they should not affect the molecular orbital configuration and they shouldn't affect molecular overlap. Am I understanding that correctly or is my reasoning flawed? For example the electronic configuration and bond order should be the same for deuterium and H₂ based on this reasoning.

Thanks for the help.

[mjc123]

To a first approximation, you are correct. The different mass of isotopes does have a very small effect, but for most practical purposes it is negligible.

[Irlanur]

Since most chemical theories/calculations use the Born-Oppenheimer approximation, which in the easiest way means that the instantaneous movements of electrons and nuclei are independent, electronic configurations/wavefunctions for different isotopes are the same.