To determine which of the given elements will pair with a group 7 halogen like bromine (Br) in a 1:1 ratio based on the trends in valence electrons, we need to examine the valence electrons of each element.
1. Barium (Ba)
- Barium is in Group 2 of the periodic table.
- Elements in Group 2 have 2 valence electrons.
2. Aluminum (Al)
- Aluminum is in Group 13 of the periodic table.
- Elements in Group 13 have 3 valence electrons.
3. Potassium (K)
- Potassium is in Group 1 of the periodic table.
- Elements in Group 1 have 1 valence electron.
4. Sulfur (S)
- Sulfur is in Group 16 of the periodic table.
- Elements in Group 16 have 6 valence electrons.
Group 7 halogens, like bromine (Br), need 1 electron to complete their valence shell. Therefore, they tend to form a 1:1 ratio with elements that have exactly 1 valence electron.
Out of the given elements, potassium (K) has 1 valence electron. Thus, potassium will pair with bromine in a 1:1 ratio.
Therefore, the element that will pair with a group 7 halogen, such as bromine (Br), in a 1:1 ratio is:
Potassium (K).
