Give the number of core electrons for phosphorus.
A) 3
B) 6
C) 10
D) 7
E) 11

Question

Quizplus · Accepted Answer

Phosphorus has an atomic number of 15, which means it has 15 electrons total. The first two electrons fill the 1s orbital, the next two fill the 2s orbital, and the remaining six fill the 2p orbital. These valence electrons are involved in chemical bonding, while the first ten electrons (2 in the innermost shell and 8 in the second shell) are considered core electrons and do not participate in bonding. Therefore, phosphorus has 10 core electrons (3s2 + 3p6 = 10). Choice C is the only option that correctly states the number of core electrons for phosphorus.

Give the Number of Core Electrons for Phosphorus