Force of Attraction between two ions?

[Saladsamurai]

Homework Statement

Calculate the force of attraction between Ca²⁺ and O^2- ions whose centers are separated by 1.25 nm.

The Attempt at a Solution

Well, I believe this is a matter of electrostatic force (Coulomb's Law)...but I am not sure what to use for the values of q₁ and q₂
Is it just the elementary charge multiplied by 2 for each ion (since they both have a net charge of 2)?

Is this the right idea?

 

[Borek]

Yes.