Which property is primarily used to organize elements in the modern periodic table?

• A. Atomic number
• B. Atomic mass
• C. Number of neutrons
• D. Electronegativity

Answer: (A)

Verified step by step guidance

1. Understand that the modern periodic table is arranged based on a fundamental property of elements that reflects their identity and order.
2. Recall that the atomic number represents the number of protons in the nucleus of an atom, which uniquely identifies each element.
3. Recognize that earlier versions of the periodic table were sometimes organized by atomic mass, but this led to inconsistencies in element placement.
4. Note that properties like the number of neutrons or electronegativity vary among isotopes or groups and are not used for the primary organization of the table.
5. Conclude that the atomic number is the primary property used to organize elements in the modern periodic table, ensuring a consistent and logical arrangement.