What's wrong w/ this answer? Diatomic molecule oxygen O2 is rotating?

Question

in the xy plane about the z axis passing through its center, perpendicular to its length. The mass of each oxygen atom is 2.66 x 10^-26 kg, and at room temperature, the average separation distance between the two oxygen atoms is
2.02 x 10^-10 m (atoms treated as point masses). if the angular speed of the molecule about the z axis is 5.61 x10^12 rad/s, what is the rotational kinetic energy (answer in J)?


This is wrong, & I can't figure why???????
KE=(1/2)*I*omega^2
I=m*r^2 for each atom, r being half the distance that seperates them, so in total 2*m*r^2
omega= 5.61 x 10^12 rad/s

Answer 1

KE= 1/2 I Omega^2

I= 2 (m r^2) for the two atoms

KE = 1/2 * 2 * m * r^2 * Omega^2 = m * r ^2 * Omega^2
m= 2.66 e-26
r = 1/2 * 2.02 e-10 = 1.01 e-10 (remember you want radius, 1/2 the distance between them)
Omega = 5.61 e 12

I get 8.54 x 10^-21 kg m^2/s^2