Question

1. what do the periods (rows) on the periodic table represent?

the number of valence electrons
the number of neutrons in the nucleus
the number of electrons in the outermost shell
a principal energy level
clear all

Explanation:

• Analyze each option:
• Valence electrons/outermost shell electrons are related to groups (columns), not periods.
• Neutrons in the nucleus are not related to period arrangement.
• Periods (rows) in the periodic table correspond to a principal energy level (the main electron shell energy level).

Answer:

D. A principal energy level