Atomic number and not the atomic weight is the fundamental property of a element was enunciated by ?

Options

A. Dalton
B. Bohr
C. Mosley
D. Mendeleev

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the scientist who stated that the atomic number, rather than atomic weight, is the fundamental property of an element.

2. **Identifying Key Scientists**: The key scientists mentioned in the context of periodic properties are Mendeleev, Moseley, Dalton, and Bohr. Each of these scientists contributed to the field of chemistry but in different ways.

3. **Reviewing Mendeleev's Contribution**: Dmitri Mendeleev created the first periodic table based on atomic weights. However, his arrangement had some inconsistencies, which were later addressed.

4. **Introducing Moseley's Contribution**: Henry Moseley conducted experiments that led to the conclusion that atomic number (the number of protons in an atom's nucleus) is a more accurate way to organize the elements than atomic weight.

5. **Moseley’s Modern Periodic Law**: Moseley proposed the modern periodic law, which states that the properties of elements are a periodic function of their atomic numbers. This was a significant advancement over Mendeleev's periodic table.

6. **Conclusion**: Based on the above analysis, the scientist who enunciated that atomic number is the fundamental property of an element is **Henry Moseley**.

**Final Answer**: Henry Moseley

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