The properties of the elements, as well as the formulae and properties of their compounds depends in a periodic manner on the atomic weights of the elements. This periodic law was given by

Answer

To solve the question regarding who proposed the periodic law stating that the properties of elements depend on their atomic weights, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Periodic Law**: The periodic law states that the properties of elements are a periodic function of their atomic weights. This means that when elements are arranged in order of increasing atomic weight, elements with similar properties appear at regular intervals.

2. **Identifying the Scientist**: The scientist who is credited with formulating this periodic law is Dmitri Ivanovich Mendeleev, a Russian chemist.

3. **Mendeleev's Contribution**: Mendeleev arranged the known elements in a table according to their atomic weights and observed that elements with similar properties occurred at regular intervals. This led to the development of the periodic table.

4. **Conclusion**: Therefore, the answer to the question is that the periodic law was given by D.I. Mendeleev.

### Final Answer:
The periodic law was given by D.I. Mendeleev.

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