Who arranged the elements with chemically similar properties, such as lithium, sodium, and potassium, and showed that the properties of the middle element could be predicted from the properties of the other two?

Johann Dobereiner

The correct answer is option 1. Johann Dobereiner.

The scientist who arranged the elements with chemically similar properties, such as lithium, sodium, and potassium, and showed that the properties of the middle element could be predicted from the properties of the other two, is Johann Dobereiner.

Johann Dobereiner, a German chemist, proposed the concept of triads in 1817. He observed that certain groups of three elements (triads) had similar chemical properties, and the atomic mass of the middle element in each triad was approximately the average of the atomic masses of the other two elements. This concept laid the foundation for the later development of the periodic table.