How many core electrons are there in a ground state phosphorus atom?
core electrons
15-5 = ?
To determine the number of core electrons in a ground state phosphorus (P) atom, we need to know the electron configuration of phosphorus atom.
Phosphorus has an atomic number of 15, indicating that it has 15 electrons in total.
The electron configuration of phosphorus can be written as: 1s² 2s² 2p⁶ 3s² 3p³.
In this electron configuration, the first two electrons occupy the 1s orbital, the next two electrons occupy the 2s orbital, and the next six electrons occupy the 2p orbital. Finally, the remaining five electrons occupy the 3s and 3p orbitals.
Since the core electrons are the inner electrons that are closer to the nucleus, they include all the electrons except those in the outermost (valence) shell. In the case of phosphorus, the outermost shell is the third shell (3s² 3p³), so the core electrons are those in the first and second shells.
Adding up the electrons in the first and second shells, we have: 2 + 2 + 2 + 6 = 12.
Therefore, a ground state phosphorus atom has 12 core electrons.