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

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

Answer: (B)

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 of their chemical properties.
3. Recognize that arranging elements by increasing atomic number resolves these inconsistencies and groups elements with similar chemical properties into columns called groups or families.
4. Note that the periodic law states: 'The properties of elements are a periodic function of their atomic numbers,' meaning elements show repeating patterns of properties when arranged by atomic number.
5. Therefore, the elements in today's modern periodic table are arranged in order of increasing atomic number, not by discovery date, alphabetical order, or atomic mass.