How did Dmitri Mendeleev organize the elements in his periodic table?

• A. By alphabetical order of element names
• B. By the number of neutrons in each element
• C. By increasing atomic mass and grouping elements with similar chemical properties
• D. By increasing atomic number only

Answer: (C)

Verified step by step guidance

1. Understand the historical context: Dmitri Mendeleev created the periodic table before the discovery of protons and neutrons, so atomic number and neutron count were not known at that time.
2. Recognize that Mendeleev arranged elements primarily by increasing atomic mass, which was the measurable property available to him.
3. Note that Mendeleev also grouped elements with similar chemical properties into columns, which allowed him to predict the existence and properties of undiscovered elements.
4. Understand that the arrangement was not alphabetical, nor based on the number of neutrons, since these concepts were not used in his organization.
5. Summarize that Mendeleev's periodic table was organized by increasing atomic mass and by grouping elements with similar chemical properties, which was a key insight leading to the modern periodic table.