Question
Write the atomic number of the element present in the third period and seventeenth group of the periodic table.
Solution
In the third period the filling up of only 3s and 3p-orbitals occur. Therefore, in this period there are only two s- and six p-biock elements. Since the third period (n = 3) starts with Z = 11 and ends at Z = 18, hence the element is chlorine (CI) with atomic number (Z) = 17 which is present in the third period and seventeenth group of the periodic table.
