How are the elements arranged in the modern periodic table?

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

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 arranged by atomic number.
4. Note that the number of neutrons varies among isotopes of the same element and is not used to arrange elements in the periodic table.
5. Confirm that elements are not arranged alphabetically, as this would not reflect their chemical properties or periodic trends.