Re: [Phys-L] Energy & Bonds

[rjensen@ualberta.ca]

> Instructors should keep in mind that bonded O_2 has less mass than 2 oxygen atoms.  Maybe if biology and chemistry introduced this concept it would be simpler to explain forming and breaking of bonds??  Instructors should spend time up front explaining the MAKING of bonds (decrease of mc^2). Then to break a bond you have to add enough energy to have the separate masses, followed by a rebonding into a different form with less mc^2 and more KE.

Does the decreased mass account for the exact binding energy (498
kJ/mol; 5.16 eV)? or are other factors at play?

I can find masses of atomic isotopes, but not molecular entities.
References to this information would be appreciates so I can do the
above calculation.

Thanks,
 Dr. Roy Jensen
(==========)-----------------------------------------¤
 Lecturer, Chemistry
 E5-33F, University of Alberta
 780.248.1808