Write The Ground State Electron Configuration For An Arsenic Atom, Showing The Number Of Electrons In Each Subshell
The correct answer and explanation is :
The ground-state electron configuration for an arsenic (As) atom, which has an atomic number of 33, is:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p³
Explanation (300 Words)
Arsenic (As) is an element in Group 15 (or VA) of the periodic table and is classified as a metalloid. To determine its ground-state electron configuration, we follow the Aufbau principle, which states that electrons occupy orbitals in order of increasing energy.
Step 1: Identify the Number of Electrons
Since arsenic has an atomic number of 33, it has 33 electrons in a neutral state.
Step 2: Fill the Electron Orbitals in Order of Energy Levels
Electrons fill the orbitals according to the following sequence:
- 1s² → The 1s orbital can hold 2 electrons.
- 2s² → The 2s orbital can hold 2 electrons.
- 2p⁶ → The 2p orbital can hold 6 electrons.
- 3s² → The 3s orbital can hold 2 electrons.
- 3p⁶ → The 3p orbital can hold 6 electrons.
- 4s² → The 4s orbital can hold 2 electrons.
- 3d¹⁰ → The 3d orbital can hold 10 electrons.
- 4p³ → The 4p orbital can hold 3 electrons.
Step 3: Verify the Total Number of Electrons
Adding up all the electrons:
2 (1s) + 2 (2s) + 6 (2p) + 2 (3s) + 6 (3p) + 2 (4s) + 10 (3d) + 3 (4p) = 33 electrons, which is correct.
Why 4p³?
Arsenic belongs to Group 15, meaning it has three valence electrons in the p subshell (4p³). These electrons play a key role in arsenic’s chemical behavior, including bonding and reactivity.
Thus, the correct ground-state electron configuration of As is:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p³.