How are the elements on the periodic table primarily arranged?

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

Answer: (A)

Verified step by step guidance

1. Understand that the periodic table is a systematic arrangement of elements based on their properties.
2. Recall that the atomic number of an element is the number of protons in its nucleus, which uniquely identifies each element.
3. Recognize that the modern periodic table arranges elements in order of increasing atomic number, not by atomic mass or other properties.
4. Note that arranging by atomic number ensures elements with similar chemical properties fall into the same groups or columns.
5. Conclude that the primary arrangement principle of the periodic table is by increasing atomic number.