1. Determine the Electron Configuration:
* Phosphorus (P) has an atomic number of 15, meaning it has 15 electrons.
* The electron configuration of phosphorus is: 1s² 2s² 2p⁶ 3s² 3p³
2. Identify Core Electrons:
* Core electrons are the electrons in the inner energy levels (shells) of an atom.
* Valence electrons are the electrons in the outermost energy level.
3. Count the Core Electrons:
* The core electrons in phosphorus are those in the 1s, 2s, and 2p orbitals:
* 1s² (2 electrons)
* 2s² (2 electrons)
* 2p⁶ (6 electrons)
4. Total Core Electrons: 2 + 2 + 6 = 10 core electrons
