How are the elements in the periodic table primarily arranged?

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

Answer: (B)

Verified step by step guidance

1. Understand that the periodic table is a systematic arrangement of elements based on their properties.
2. Recall that early versions of the periodic table were arranged by increasing atomic mass, but this caused inconsistencies in element properties.
3. Recognize that the modern periodic table is arranged by increasing atomic number, which is the number of protons in an atom's nucleus.
4. Know that arranging elements by atomic number aligns elements with similar chemical properties into columns (groups or families).
5. Conclude that the primary arrangement of elements in the periodic table is by increasing atomic number, not by atomic mass, number of neutrons, or alphabetical order.