question_answer 1)

Write the atomic number of the element present in the third period and seventeenth group of the periodic table.

Answer:

The third period starts with \[3{{s}^{1}}\] and completes with\[3{{p}^{6}}\]. Thus, the electronic configuration of the element in question is: \[[Ne]3{{s}^{2}}3{{p}^{5}}\] Therefore, the atomic number of the element is \[=10+2+5=17\].