If an atom has the electron conifig.1s^2 2s^2 2p^3, is the p orbital the valence shell or is it the 2p and 2s?

Question

Because the 2p orbital has slightly more energy than the 2s orbital, I was wondering which one is considered the valence shell? Is it the 2p orbital because it is the highest on the energy spectrum, or is it both the 2p and the 2s orbitals because they both have the same principle quantum number?

Answer 1

its always the last s number so its 2s

Answer 2

1s2 2s2 2p3 is nitrogen. It has 5 electrons in the valence shell according to electron population in the 2s and the 2p orbitals.

In general, you want to group it by principal quantum numbers. The greatest changes in energy state is between different levels of principal quantum numbers. All the orbitals allowed for a given principal quantum number is considered to be in the same shell, even though the orbitals have slightly different energy states.

When you get into the d and f blocks, the simple octet rule breaks down as far as figuring out common oxidation states go. An element will partially filled d or f orbitals is kind of a mess. The valence shell is still all the electrons with the same principal number. It's just that the octet rule for predicting chemical behavior of the element doesn't work.