How are the elements organized on the periodic table?

• A. By increasing atomic mass only
• B. By alphabetical order of element names
• C. By their chemical reactivity
• D. By increasing atomic number

Answer: (D)

Verified step by step guidance

1. Understand that the periodic table is a systematic arrangement of elements based on their properties.
2. Recall that the atomic number of an element is the number of protons in its nucleus, which uniquely identifies each element.
3. Recognize that the modern periodic table is organized by increasing atomic number, not atomic mass, alphabetical order, or chemical reactivity.
4. Know that arranging elements by atomic number results in a periodic pattern of chemical properties, which is the basis for the table's structure.
5. Conclude that the correct organization principle of the periodic table is by increasing atomic number, which explains the periodic trends observed.