To determine which element will pair with a group 7 halogen, such as chlorine (Cl), in a 1:1 ratio based on valence electrons, we need to understand the valence electron configuration of each of the given elements. Group 7 halogens, like chlorine, have 7 valence electrons. They need 1 more electron to achieve a stable octet configuration. Therefore, they will pair with elements that have 1 valence electron to form a 1:1 ratio.
Let's analyze the valence electrons of each given element:
1. Carbon (C): Carbon is in group 14 of the periodic table, which means it has 4 valence electrons.
2. Sodium (Na): Sodium is in group 1 of the periodic table, which means it has 1 valence electron.
3. Boron (B): Boron is in group 13 of the periodic table, which means it has 3 valence electrons.
4. Phosphorus (P): Phosphorus is in group 15 of the periodic table, which means it has 5 valence electrons.
Now, we need to find out which element pairs with chlorine (Cl) in a 1:1 ratio:
- Carbon (C) has 4 valence electrons, so it does not pair in a 1:1 ratio with chlorine (Cl).
- Sodium (Na) has 1 valence electron, so it can donate 1 electron to chlorine (Cl), achieving a 1:1 pairing.
- Boron (B) has 3 valence electrons, so it does not pair in a 1:1 ratio with chlorine (Cl).
- Phosphorus (P) has 5 valence electrons, so it does not pair in a 1:1 ratio with chlorine (Cl).
Therefore, the element that pairs with chlorine (Cl) in a 1:1 ratio based on valence electrons is:
Sodium (Na).
