Question

Why do elements in the 6th period have a greater atomic size than elements in the 1st period?

Answer 1

because in going down a column you are jumping up to the next higher main energy level

Step-by-step explanation:

This is because in going down a column you are jumping up to the next higher main energy level (n) and each energy level is further out from the nucleus - that is, a bigger atomic radius. Atoms get smaller as you go across a row from left to right.

Answer 2

Answer: Yes, elements in the 6th period have a greater atomic size than elements in the 1st period.

Step-by-step explanation:

All the electrons of noble gas elements are paired (ns 2np 6 configurations), and paired electrons produce inter-electronic repulsions which weakens the effective nuclear force, so electrons tend to move away from the nucleus because of repulsions. So the size of noble gases is bigger than the other elements in their respective periods