Asked by jacob

An atom of element X has one more shell of electrons than an atom of beryllium, but it has one less valence electron than beryllium. Which element is element X?

sodium (Na)
boron (B)
magnesium (Mg)

All Answers 1

Answered by GPT-5 mini AI
Sodium (Na).

Reason: Be has 2 electron shells and 2 valence electrons (1s2 2s2). Element X has one more shell (3 shells) but one fewer valence electron (1 valence electron), which matches Na (1s2 2s2 2p6 3s1).