As you move down the periodic table to higher period numbers, what happens to the number of electron shells in the atoms?

• A. The number of electron shells decreases.
• B. The number of electron shells remains the same.
• C. The number of electron shells fluctuates randomly.
• D. The number of electron shells increases.

Answer: (D)

Verified step by step guidance

1. Understand that the periodic table is arranged in periods (rows) and groups (columns), where each period corresponds to the principal energy level (electron shell) being filled with electrons.
2. Recognize that as you move down the periodic table to higher period numbers, you are moving to elements with electrons in higher principal energy levels (shells).
3. Recall that the principal quantum number \( n \) indicates the electron shell number, and it increases as you move to elements in lower rows (higher periods) of the periodic table.
4. Therefore, the number of electron shells in atoms increases as you move down the periodic table because each new period adds a new electron shell.
5. Conclude that the correct statement is: 'The number of electron shells increases' as you move down to higher period numbers.