How is the modern periodic table arranged?

• A. By the order of element discovery
• B. By increasing atomic mass
• C. By alphabetical order of element names
• D. By increasing atomic number

Answer: (D)

Verified step by step guidance

1. Understand that the modern periodic table is arranged based on a fundamental property of elements called the atomic number, which is the number of protons in an atom's nucleus.
2. Recall that earlier versions of the periodic table were arranged by increasing atomic mass, but this caused inconsistencies in element properties and groupings.
3. Recognize that arranging elements by increasing atomic number resolves these inconsistencies because the atomic number uniquely identifies each element and determines its chemical behavior.
4. Note that the periodic table groups elements with similar chemical properties into columns called groups or families, which arise naturally when elements are ordered by atomic number.
5. Conclude that the modern periodic table is arranged by increasing atomic number, not by order of discovery, atomic mass, or alphabetical order.