Question

Would an electron have to absorb or release energy to jump from the second energy level to the third energy level according to Niels Bohr?

Answer 1

According to Bohr, the energy level nearest the nucleus, n=1, is the lowest energy shell. Successive shells are higher in energy. Your electron would have to gain energy to be promoted from n=2 to n=3 shell.

In reality, we define the energy infinitely far away from the nucleus as zero, and the actual energy of all the energy levels is negative. The n=1 (innermost) shell has the most negative energy, and the energies get larger (less negative) as we get further from the nucleus. Just the same, moving an electron from n=2 (a more negative energy level) to n=3 (a less negative energy level) requires the electron to gain energy.