Question

Arrange the following elements in the decreasing order of the number of shells. (top to bottom)

• A. Ce
• B. Rb
• C. K
• D. Na
• E. Li

Answer 1

In the modern periodic table, when we go down the group, the number of shells increases by one.
For example, hydrogen has only K shell; lithium has K and L shells; sodium has K, L and M shells and so on.