Question

Elements A, B and C have atomic numbers $17$, $19$ and $10$ respectively. State which one is: ​

(ii) a metal​

Answer 1

Electronic configuration of element B (atomic number $=19$) is $2,8,8,1$. It has one electron in its outermost shell so it loses that electron to maintain its stability. Therefore, B is a metal. ​

Additional information:​

Metals are defined as the elements which form positive ions by the loss of electrons. Potassium (atomic number $=19$) has $1$ electron in its outermost shell, so it loses one electron to complete its octet.​