What is the electron configuration for phosphorus (P)? [Ne3s23p4] [He3s23p3] [1s2 2s2 2p6 3s2 3p4] [1s2 2s2 2p6 3s2 3p3]
The Correct Answer and Explanation is:
Correct answer:
[1s² 2s² 2p⁶ 3s² 3p³]
Explanation:
Phosphorus (P) is an element in the third period and group 15 of the periodic table, with an atomic number of 15. This means a neutral phosphorus atom contains 15 protons and 15 electrons. To determine the electron configuration, electrons are filled into atomic orbitals in a specific order based on the Aufbau principle, which prioritizes orbitals with lower energy levels.
The first two electrons occupy the 1s orbital, the next two go into the 2s orbital, and the next six fill the 2p orbital, completing the second shell. That accounts for 10 electrons:
1s² 2s² 2p⁶
The next two electrons fill the 3s orbital, and the remaining three electrons enter the 3p orbital. This completes the configuration for all 15 electrons:
1s² 2s² 2p⁶ 3s² 3p³
This configuration matches the option:
[1s² 2s² 2p⁶ 3s² 3p³]
This arrangement reveals that phosphorus has five valence electrons located in the third shell (3s² 3p³). These valence electrons explain the element’s chemical properties, such as its tendency to form three covalent bonds in molecules like phosphine (PH₃).
Incorrect choices:
- [Ne 3s² 3p⁴] represents sulfur (atomic number 16), not phosphorus.
- [He 3s² 3p³] is incorrect because helium (He) only accounts for two electrons, whereas phosphorus has 15.
- [1s² 2s² 2p⁶ 3s² 3p⁴] corresponds to sulfur, not phosphorus.
Thus, the accurate configuration for phosphorus is [1s² 2s² 2p⁶ 3s² 3p³].
