Helpful steps?

Question

Calculate the predicted atomic radius for potassium, K, given the atomic radius of rubidium, Rb, (0.247 nm) and cesium, Cs, (0.265 nm).

Answer 1

If that's the only information available to you I would suggest that you subtract 0.265-0.247 to find how much the radius decreases from period 6 to period 5 and subtract that difference from Rb to make an educated guess at K that's down one more period.

Answer 2

we only subtract 0.265 out off 0.247 to find the radius decreases from period 6 to period 5. so the answer is = 0.018 nm.

Answer 3

0.229nm