26 POINTS AND Select the correct answer.

Scientists classify rocks into three different types. What is the main basis for the classification system they chose?

A. color of the rock
B. shape of the rock
C. how the rock formed
D. who discovered the rock

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

the answer for sodium is 0.186

the answer for rubidium is 0.251