Question

in which of the following groups of ions are the charges all shown correctly? ca²+, al³+, br- k²-, f-, mg²+ li-, o²-, s²+ na+, i-, rb-

Explanation:

• For \(Ca^{2 +}\): Calcium (\(Ca\)) is in Group 2 of the periodic table. Elements in Group 2 tend to lose 2 electrons, so the ion charge is \(+2\).
• For \(Al^{3+}\): Aluminium (\(Al\)) is in Group 13. It loses 3 electrons to form an ion with a \(+3\) charge.
• For \(Br^{-}\): Bromine (\(Br\)) is in Group 17. It gains 1 electron to form an ion with a \(-1\) charge.

Now let's check other options:

• In \(K^{2 -}\), potassium (\(K\)) is in Group 1. It loses 1 electron to form \(K^{+}\), not \(K^{2 -}\).
• In \(Li^{-}\), lithium (\(Li\)) is in Group 1. It loses 1 electron to form \(Li^{+}\), not \(Li^{-}\). Also, sulfur (\(S\)) is in Group 16 and gains 2 electrons to form \(S^{2 -}\), not \(S^{2+}\).
• In \(Rb^{-}\), rubidium (\(Rb\)) is in Group 1. It loses 1 electron to form \(Rb^{+}\), not \(Rb^{-}\).

Answer:

\(Ca^{2 +},Al^{3+},Br^{-}\)