Question

Which of the following elements has the fewest valence electrons?

Answer 1

Answer is: lithium has the fewest valence electrons.

1) Electron configuration of lithium: ₃Li: 1s² 2s¹, it has one valence electron in 2s orbital.

2) Electron configuration of beryllium: ₄Be: 1s² 2s², it has two valence electrons in 2s orbital.

3) Electron configuration of boron: ₅B: 1s² 2s² 2p¹, it has three valence electrons in 2s and 2p orbitals.

4) Electron configuration of carbon: ₄C: 1s² 2s² 2p², it has four valence electrons in 2s and 2p orbitals.

Answer 2

I think your claim is correct.

Because for Li, Be, B and C, their valence electron are all located in the second orbital, so based on their sequence, Li must has fewest valence electrons.