The ions of potassium (K) and calcium (Ca) both contain 18 electrons.?

Question

Would you expect the chemical behaviors of these elements to be similar

Answer 1

similar but not exactly the same. We do a lab in my class where we compare the alkali metal to each other and to the alkali earth metals.
The reaction of the alkali metals and Alkali Earth metals to water is similar, both making hydroxides, but the reaction rate of the alkali Earth metals is much slower.

Answer 2

K and the other Alkali metals will react faster than the Ca and its' Alkali Earth buddies.

It is easier for K to loose that one electron than it for Ca to loose its' two.

Get an "A".