What is the correct electron configuration of phosphorus $(P)$?
A. $1 s^2 2 s^2 2 p^6 3 s^2 3 p^3$
B. $1 s^2 2 s^2 2 p^3 3 s^2 3 p^3$
C. $1 s^2 2 s^2 2 p^6 2 d^5$
D. $1 s^2 2 s^2 2 p^6 3 s^1 3 p^4$
Answer (2)
Determine the number of electrons in phosphorus: 15.
Fill the electron shells and subshells according to the Aufbau principle.
Write the electron configuration based on the filling order: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 3 .
The correct electron configuration of phosphorus (P) is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 3 .
Explanation
Determine the number of electrons Phosphorus (P) has an atomic number of 15, which means a neutral phosphorus atom has 15 electrons. We need to determine the correct electron configuration that represents the arrangement of these 15 electrons in the atom's energy levels and sublevels.
Apply the Aufbau principle We fill the electron shells and subshells according to the Aufbau principle, which dictates the order of filling orbitals: 1s, 2s, 2p, 3s, 3p, 4s, 3d, etc. The s subshells can hold up to 2 electrons, p subshells can hold up to 6 electrons, and d subshells can hold up to 10 electrons.
Fill the subshells Filling the subshells until all 15 electrons are assigned:
1s can hold up to 2 electrons: 1 s 2 (2 electrons used)
2s can hold up to 2 electrons: 2 s 2 (4 electrons used)
2p can hold up to 6 electrons: 2 p 6 (10 electrons used)
3s can hold up to 2 electrons: 3 s 2 (12 electrons used)
3p can hold up to 3 electrons: 3 p 3 (15 electrons used)
Write the electron configuration The electron configuration is therefore 1 s 2 2 s 2 2 p 6 3 s 2 3 p 3 .
Compare with the options Comparing the derived electron configuration with the given options, we find that option A matches our result.
Examples
Understanding electron configuration is crucial in chemistry for predicting how elements will interact to form chemical bonds. For instance, knowing the electron configuration of phosphorus helps us understand its bonding behavior in compounds like phosphates, which are essential in biological systems for energy transfer (ATP) and DNA structure. Similarly, in materials science, the electron configuration dictates the electronic and optical properties of phosphorus-containing semiconductors used in electronic devices.
The correct electron configuration of phosphorus is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 3 . This matches with option A. Phosphorus has a total of 15 electrons, which fill the orbitals according to the Aufbau principle.
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