In the modern periodic table, how are atoms (elements) arranged?

• A. Alphabetically by element name, grouped by common isotopes.
• B. By increasing atomic number, so elements with similar properties recur periodically in columns (groups).
• C. By increasing atomic mass only, with no exceptions.
• D. By decreasing atomic number, with metals always placed above nonmetals.

Answer: (B)

Verified step by step guidance

1. Understand that the modern periodic table arranges elements based on a fundamental property of atoms called the atomic number, which is the number of protons in the nucleus of an atom.
2. Recognize that arranging elements by increasing atomic number means listing them in order from the element with the smallest number of protons to the largest.
3. Know that elements with similar chemical properties are grouped together in vertical columns called groups or families, which recur periodically as the atomic number increases.
4. Recall that this periodic recurrence of properties is the basis for the periodic law, which states that the properties of elements are a periodic function of their atomic numbers.
5. Therefore, the correct arrangement is by increasing atomic number, with elements having similar properties appearing in the same columns, making the periodic table a powerful tool for predicting element behavior.