Question

What electron configuration represents an atom in the excited state?

Answer 1

Hint : To understand the excited state of the configuration, we must understand and learn the electron configuration and different energy level orbits. In the excited state, the electrons of the outermost or valence orbit get excited i.e. get energized and they jump to the higher energy level from their standard energy level at the ground state.

Complete Step By Step Answer:
To understand the electronic configuration of the excited state, we must first understand the excitation of the electrons.
At the ground state, the electrons have the least possible energy and hence are the most stable at this energy level.
To transfer an electron to an excited state, energy is required to be given externally as the energy is higher at the bigger energy levels.
To energize the electron, energy is given in the form of photons. The photons are bombarded over the electrons, and the electrons absorb the photon energy and if the energy is sufficient, it will reach a higher energy level. For most of the cases, the energy is only sufficient to reach the immediate higher level energy state.
To understand the excited electronic configuration in excited state, let us consider an example of Sodium
The electronic configuration of Sodium at ground level is $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{1}}$
Now, the inner orbits are completely filled and hence, they are stable. The valence electron is unpaired and the farthest from the nucleus. Hence, on excitation only the valence electron will try to jump to a higher orbit.
Now, let us suppose that the energy is enough to reach the immediate higher energy level. Hence, the electron configuration after the electron jumps to higher energy level is $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{p}^{1}}$
This is the excited electronic configuration. Hence, the electronic configuration where the electron is present in a higher energy level orbit compared to the ground state represents the excited state.

Note :
The simplest method to find whether the electron is in an energized state is to compare the given electronic configuration with the electronic configuration of the atom in the ground state. The energized state of an electron is a highly unstable condition and thus the electron will fall back to the ground state and emit the energy absorbed in the excitation. This is one of the basic principles used in the Light Emitting Diodes.