The periodic table is organized by

• A. Alphabetical order
• B. Mass number only
• C. Number of isotopes
• D. Physical and chemical properties

Answer: (D)

The periodic table is organized to reveal recurring physical and chemical properties of elements as their electrons are arranged. As atomic number increases, the pattern of valence electrons repeats in a way that groups of elements behave similarly and form predictable trends in reactivity, bonding, and other properties. Elements in the same column share similarities because they have the same or similar valence electron configurations, while moving across a period shows gradual changes as a new electron shell begins to fill. This organization lets you predict how an element might react, what kinds of bonds it forms, and where it sits in relation to others with comparable behavior. Alphabetical order wouldn’t show these patterns, organizing by mass ignores how properties shift with electron structure, and counting isotopes doesn’t correspond to how elements actually behave chemically.