Which statement correctly compares periods and groups in the modern periodic table?
- A) Periods are vertical columns containing elements with identical valence electron configurations, while groups are horizontal rows representing increasing mass numbers.
- B) Periods are horizontal rows that correspond to the number of occupied electron shells, while groups are vertical columns containing elements that share similar chemical properties due to having the same number of valence electrons.
- C) Periods are horizontal rows where all elements exhibit identical chemical reactivity, while groups are vertical columns where elements have the same principal quantum number.
- D) Periods are vertical columns showing changes in nuclear charge, while groups are horizontal rows categorized strictly by physical states at room temperature.
