Question

Please help i don't get the answer. How much energy, in kilojoules per mole, is released when an electron makes a transition from n=5 to n=2 in an hydrogen atom?

Answer 1

E = 2.180E-19J x (1/4 - 1/25)
1/4 is 1/n^2 = 1/2^2 for the lower level
1/25 is 1/n^2 = 1/5^2 for the higher level

Answer 2

-5.10x10-19