Question

What is the Kinetic Energy of an electron in the n=4 Bohr orbit?

Answer 1

Do you have a velocity?

Answer 2

nope

Answer 3

are you thinking KE=1/2(mv^2) ?

Answer 4

I was thinking more of hf-hf(sub-0)=KE

Answer 5

If you're sure you need KE and not total energy, the following expression gives the kinetic energy of an electron in a Bohr orbital, n:\[KE=\frac{ 13.6Z ^{2} }{n ^{2} }eV\]where Z is the atomic number; and n is the orbital number. For hydrogen, Z=1, which simplifies the equation to:\[KE=\frac{ 13.6 }{ n ^{2} }eV\]. Be sure to note that the units of the answer will be in eV. If you need other units, such as joules, you'll need to convert once you've got an answer.

Answer 6

Note that 13.6eV is worth memorizing because it's the ground state energy for the Hydrogen atom's electron. It's also known as the Rydberg energy.

Answer 7

Oh... I didn't convert to Joules... Thank you.

Answer 8

You're welcome.