\(\left\{{}\begin{matrix}\text{pA+pB=19}\\\text{pB-pA=9}\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}\text{pB=14}\\\text{pB=5}\end{matrix}\right.\)
\(\text{B: 1s2 2s2 2p6 3s2 3p2}\)
Ở ô 14 chu kì 3 nhóm IVA
\(\text{B: 1s2 2s2 2p1}\)
Ô 5 chu kì 2 nhóm IIIA