Question

Which of the following electronic configuration shows that the atom is in excited state?

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

Answer 1

The correct option is E $1s^{2}2s^{2}3s^1$

$1s^{2}2s^{2}3s^1$ is the electronic configuration that shows that the atom is in excited state. The corresponding ground state electronic configuration is $1s^{2}2s^{2}2p^1$. The configuration that corresponds to the lowest electronic energy is called the ground state. Any other configuration is an excited state. The valance electron in given configuration is excited from $2p$ subshell to $3s$ energy state as deduced from the Aufbau principle.