Answer: Option B) oxygen (O)
Explanation:
The number of valence electrons in an element refers to the number of electrons in its outermost shell.
Hence, for each of the given elements, they are as follows:
- Phosphorus (P) has an atomic number of 15, with an electronic configuration of 1s2, 2s2 2p6, 3s2 3p3. Hence, it has 5 valence electrons.
- Oxygen (0) has an atomic number of 8, with an electronic configuration of 1s2, 2s2 2p6. Hence, it has 6 valence electrons.
- Sodium (Na), has an atomic number of 11, with an electronic configuration of 1s2, 2s2 2p6, 3s1. Hence, it has 1 valence electron.
- Magnesium (Mg) has an atomic number of 12, with an electronic configuration of 1s2, 2s2 2p6, 3s2. Hence, it has 2 valence electrons.
Thus, oxygen with 6 outermost electrons has the greatest number of valence electrons among the given elements.
