The property used by Mendeleev to classify the elements in his periodic table is `"________"`.

Options

A. There is no correlation in the properties and atomic weights of the elements
B. The properties of the elements are a periodic function of their atomic numbers
C. The properties of the elements are a periodic function of their atomic weights
D. The properties of the elements are a periodic function of their empirical formula.

Answer

**Step-by-Step Solution:**

1. **Understanding Mendeleev's Contribution**: Dmitri Mendeleev is known for creating one of the first periodic tables of elements. His work laid the foundation for the modern periodic table.

2. **Identifying the Property Used**: Mendeleev classified the elements based on their atomic weights. He observed that when elements were arranged in order of increasing atomic weight, certain properties of the elements appeared to repeat periodically.

3. **Periodic Function of Atomic Weight**: Mendeleev's principle can be summarized as: "The properties of the elements are a periodic function of their atomic weight." This means that elements with similar properties occur at regular intervals when arranged by atomic weight.

4. **Challenges Faced**: While Mendeleev's periodic table was groundbreaking, he faced challenges with elements that did not fit neatly into the order of atomic weights. For instance, he placed tellurium before iodine to group elements with similar properties, even though tellurium had a higher atomic weight than iodine.

5. **Conclusion**: The correct answer to the question is that Mendeleev used "atomic weight" as the property to classify the elements in his periodic table.

**Final Answer**: The property used by Mendeleev to classify the elements in his periodic table is "atomic weight".

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