Question

If in the ground state an atom has seven valence electrons, which of the following is the correct electronic configuration of the atom in the ground state?

• A. $3s^{1}3p^6$
• B. $3s^{6}3p^1$
• C. $3s^{1}3p^{4}3d^2$
• D. $3s^{3}3p^{4}3d^1$
• E. $3s^{2}3p^5$

Answer 1

The correct option is E $3s^{2}3p^5$

The correct electronic configuration of the atom in ground state is $3s^{2}3p^5$. Here, 3s orbital will be completely filled before an electron enters 3p orbital.
In excited state it would be $3s^{1}3p^6$.