The most energetic electron in any atom at the end of a period of the periodic table is in:
A)an ℓ=0 state
B)an ℓ=1 state
C)an ℓ=2 state
D)an n = 0 state with unspecified angular momentum
E)an n = 1 state with unspecified angular momentum

Question

Quizplus · Accepted Answer

The end of a period corresponds to the highest principal quantum number in that period. For example, in period 1, the highest principal quantum number is n=1, while in period 2, the highest principal quantum number is n=2. The most energetic electron in any atom at the end of a period will be in the highest energy level available, which corresponds to the highest value of n. However, within a given energy level, the energy of the electron depends on its angular momentum, characterized by the quantum number ℓ. The energy of an electron in a given energy level typically increases with increasing value of ℓ, so the most energetic electron in any atom at the end of a period will be in an ℓ=1 state, which is higher in energy than an ℓ=0 state and lower in energy than an ℓ=2 state.

The Most Energetic Electron in Any Atom at the End