To determine which element has the greatest number of valence electrons, let's carefully examine the electron configurations provided for each element in the table.
1. Hydrogen (Period 1):
- Electron Configuration: [tex]\( 1s^1 \)[/tex]
- Hydrogen has 1 valence electron (the electron in the [tex]\( 1s \)[/tex] orbital is its only electron, making it the valence electron).
2. Lithium (Period 2):
- Electron Configuration: [tex]\( 1s^2 2s^1 \)[/tex] or [tex]\( [He] 2s^1 \)[/tex]
- Lithium has 1 valence electron (the electron in the [tex]\( 2s \)[/tex] orbital).
3. Sodium (Period 3):
- Electron Configuration: [tex]\( 1s^2 2s^2 2p^6 3s^1 \)[/tex] or [tex]\( [Ne] 3s^1 \)[/tex]
- Sodium has 1 valence electron (the electron in the [tex]\( 3s \)[/tex] orbital).
4. Potassium (Period 4):
- Electron Configuration: [tex]\( 1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 \)[/tex] or [tex]\( [Ar] 4s^1 \)[/tex]
- Potassium has 1 valence electron (the electron in the [tex]\( 4s \)[/tex] orbital).
From this analysis, we can see that each of these Group 1 elements (Hydrogen, Lithium, Sodium, and Potassium) has exactly 1 valence electron. Therefore, they all have the same number of valence electrons.
Thus, the correct answer to the question "Atoms of which element have the greatest number of valence electrons?" is:
c. They all have the same number of valence electrons.
