How are elements arranged in the modern periodic table?

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

Answer: (A)

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 the pattern properly.
3. Recognize that arranging elements by increasing atomic number resolves these inconsistencies and reflects the periodic law, which states that the properties of elements repeat periodically when elements are ordered by atomic number.
4. Note that the number of neutrons varies among isotopes of the same element and is not used for arranging elements in the periodic table.
5. Conclude that the correct way elements are arranged in the modern periodic table is by increasing atomic number.