How many unpaired electrons are present in the ground state P atom?
0
3
1
2
4
The correct answer and explanation is :
The correct answer is 3 unpaired electrons.
Explanation:
Phosphorus (P) has an atomic number of 15, meaning it has 15 electrons in its neutral ground state. To determine how many unpaired electrons are present in the ground state of a phosphorus atom, we need to look at the electron configuration of the atom.
The electron configuration of phosphorus can be written as:
[ 1s^2 2s^2 2p^6 3s^2 3p^3 ]
This shows that:
- The first two electrons fill the 1s orbital: ( 1s^2 )
- The next two electrons fill the 2s orbital: ( 2s^2 )
- The next six electrons fill the 2p orbitals: ( 2p^6 )
- The next two electrons fill the 3s orbital: ( 3s^2 )
- The last three electrons occupy the 3p orbitals: ( 3p^3 )
Now, let’s focus on the 3p orbitals, which are the most relevant for determining the number of unpaired electrons. The 3p subshell can hold a maximum of 6 electrons, but phosphorus only has 3 electrons in this subshell.
The 3p orbitals will be filled according to Hund’s rule, which states that electrons will fill degenerate orbitals (orbitals with the same energy level) singly before pairing up. Therefore, the three electrons in the 3p orbitals will each occupy one of the three available 3p orbitals, and none of them will be paired.
As a result, all three electrons in the 3p subshell are unpaired.
Thus, the phosphorus atom in its ground state has 3 unpaired electrons.