How are elements arranged in the modern periodic table?

• A. By increasing atomic mass
• B. By the number of neutrons
• 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 the nucleus of an atom.
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 arranging elements by increasing atomic number resolves these inconsistencies because the atomic number uniquely identifies each element and determines its chemical properties.
4. Note that the number of neutrons varies among isotopes of the same element and does not affect the element's position in the periodic table.
5. Understand that alphabetical order is not used because the periodic table is designed to reflect periodic trends in element properties, which depend on atomic number, not names.