Question

according to the periodic table, which of these elements has the most electron energy levels?
a. sodium (na)
b. rubidium (rb)
c. calcium (ca)
d. fluorine (f)

Explanation:

Step1: Recall electron - energy - level rule

The number of electron energy levels of an element is equal to its period number in the periodic table.

Step2: Find the period of each element

Sodium (Na) is in period 3. Rubidium (Rb) is in period 5. Calcium (Ca) is in period 4. Fluorine (F) is in period 2.

Step3: Compare the period numbers

Since 5 > 4 > 3 > 2, rubidium has the highest period number among the given elements.

Answer:

B. rubidium (Rb)