How is the modern periodic table arranged?

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

Answer: (C)

Verified step by step guidance

1. Understand that the modern periodic table is arranged based on a fundamental property of elements called the atomic number, which is the number of protons in an atom's nucleus.
2. Recall that earlier versions of the periodic table were sometimes arranged by increasing atomic mass, but this led to inconsistencies in element properties.
3. Recognize that arranging elements by increasing atomic number resolves these inconsistencies and groups elements with similar chemical properties into columns (groups or families).
4. Note that the order of element discovery or alphabetical order of element names are not used for the arrangement because they do not reflect the elements' chemical behavior or structure.
5. Therefore, the modern periodic table is arranged by increasing atomic number, which organizes elements in a way that highlights periodic trends and chemical similarities.