How are the elements in today's modern periodic table arranged?

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

Answer: (C)

Verified step by step guidance

1. Understand that the modern periodic table is organized based on a fundamental property of atoms 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 based on their chemical 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 behavior.
4. Note that the periodic table groups elements with similar chemical properties into columns called groups or families, and these groups repeat periodically as the atomic number increases.
5. Conclude that the correct arrangement of elements in the modern periodic table is by increasing atomic number, not by alphabetical order, atomic mass, or number of neutrons.