Which electron configuration represents an atom in an excited state? ? 1s² 2s² 2p³ 3s¹ ? 1s² 2s² 2p? 3s¹ ? 1s² 2s³ 2p³ 3s¹ ? 1s² 2s² 2p³
The Correct Answer and Explanation is:
The correct electron configuration that represents an atom in an excited state is:
1s² 2s² 2p³ 3s¹
In an atom, electrons are normally arranged in the lowest possible energy levels, which is called the ground state. However, when an atom absorbs energy (such as from light or heat), some of its electrons can jump to higher energy levels, resulting in what is known as the excited state.
Explanation:
- Ground state configuration: In the ground state, electrons fill the atomic orbitals starting with the lowest energy levels. The electron configuration for the ground state of an atom with 9 electrons (such as fluorine) would be 1s² 2s² 2p⁵. In this configuration, all electrons are in the most stable arrangement.
- Excited state configuration: In an excited state, one or more electrons are promoted to higher energy levels. This could involve an electron moving from the 2p orbital to the 3s orbital, for example. This is what happens in the configuration 1s² 2s² 2p³ 3s¹. Here, instead of having all three electrons in the 2p orbital (as would be the case in the ground state), one electron has been excited to the 3s orbital.
In this configuration, the atom has absorbed energy, and the electron configuration no longer represents the most stable arrangement. This excited state is temporary, and the atom will typically return to the ground state by releasing the excess energy, often in the form of light.
The other configurations you provided are either incomplete or do not represent a typical excited state:
- 1s² 2s² 2p? 3s¹ lacks the proper number of electrons to be a valid configuration for an atom in an excited state.
- 1s² 2s³ 2p³ 3s¹ is invalid because it suggests that the atom has more than the allowed number of electrons in the 2s orbital (which can hold a maximum of 2 electrons).
- 1s² 2s² 2p³ represents a stable configuration (with all electrons in the lowest energy orbitals) and not an excited state.
