Question

Rank these atoms and ions according to radius.
K-, K+, K

Answer 1

First of all, you should know that the atomic radius is the distance between the nucleus and the outermost electron shell. Going by this, an atom having greater no. of electron shells would have a larger radius naturally. Again, electron shell are constituted of electrons. Greater the number of electrons, greater is the no. of electron shells usually. Then, K- would have a greater number of electrons than K which in turn will have greater no. of electrons than K+.Hence, the order will be K->K>K+. Hope this helps.