Question

which of the following elements has the same number of valence electrons as the element boron, b, atomic #5?
carbon, c, atomic #6
beryllium, be, atomic #4
mercury, hg, atomic #80
aluminum, al, atomic #13

Explanation:

Step1: Determine boron's valence electrons

Boron (B) has atomic number 5. Its electron - configuration is 1s²2s²2p¹. It has 3 valence electrons.

Step2: Analyze each option

• Carbon (C) with atomic number 6 has electron - configuration 1s²2s²2p² and 4 valence electrons.
• Beryllium (Be) with atomic number 4 has electron - configuration 1s²2s² and 2 valence electrons.
• Mercury (Hg) with atomic number 80 has a complex electron - configuration but has 2 valence electrons in its outermost shell.
• Aluminum (Al) with atomic number 13 has electron - configuration 1s²2s²2p⁶3s²3p¹. It has 3 valence electrons.

Answer:

D. Aluminum, Al, atomic #13