How is the modern periodic table organized?

• 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 organized 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 because some elements did not fit well in groups with similar properties.
3. Recognize that the atomic number provides a more accurate and consistent way to order elements because it directly relates to the element's identity and chemical behavior.
4. Know that arranging elements by increasing atomic number results in a periodic pattern of chemical properties, which is the basis for the periodic law.
5. Therefore, the modern periodic table is organized by increasing atomic number, not by order of discovery, atomic mass, or alphabetical order.