1. Find the element's atomic number: Phosphorus has an atomic number of 15, meaning it has 15 protons and 15 electrons.
2. Identify the preceding noble gas: The noble gas that comes before phosphorus on the periodic table is Neon (Ne), which has an atomic number of 10.
3. Write the noble gas symbol in brackets: This represents the filled electron shells up to Neon. So we start with [Ne].
4. Fill in the remaining electrons: Phosphorus has 5 more electrons than Neon. We need to account for these. The electron configuration for the remaining electrons is 3s² 3p³.
Putting it all together, the noble gas notation for phosphorus is:
[Ne] 3s² 3p³
