Question

In an atom, an electron in which of these sublevels can absorb a photon of energy but cannot emit one?

a. 3s
b. 2s
c. 3p
d. 1s
e. 3f

Would it be 1s? I don't really understand, if someone could explain this to me I'd appreciate it

Answer 1

Yes, it's the 1s. An electron in the 1s level can absorb energy and promote it to the the 2s (actually it can't go to the 2s BUT that IS higher), 2p, 3p, etc. While electrons in the outer levels can emit a photon while the electrons move to a lower level but at the 1s level, there is no lower level to go to.

Answer 2

That makes sense, thank you!