Question

Who gives the law of triads?

Answer 1

Hint:The law of triads was an attempt in the grouping of elements based on similar physical and chemical properties. The scientist who has this law is known for the periodic law of chemical elements. He is also credited to inventing the first lighter which is named in his memory. In the later stages he became a professor of chemistry and pharmacy at the University of Jena, Germany.

Complete step-by-step answer:We know that in the course of 17th and 18th century, many new elements were discovered Due to this the broad classification of elements as metals and non-metals became inefficient and obsolete.
Several experiments were carried out in order to identify elements having similar physical and chemical properties and hence can be grouped together.
Dobereiner stated in the law of triads that the arithmetic mean of the atomic masses of the first and third element in the triad should be equal to or almost equal to the atomic mass of the second element present in the triad. He also suggested that this law could be extended for other quantifiable properties of elements for e.g. density.
The first of these triads were identified in 1817 and consisted of the alkali earth metals, calcium, strontium and barium.
Thus, we can conclude that the law of triads was given by the scientist Johann Wolfgang Dobereiner.

Additional information:
There more triads were identified by the end of 1829. The three triads are mentioned below:
Triad 2:
- Lithium
- Sodium
- Potassium
Triad 3:
- Chlorine
- Bromine
- Iodine
Triad 4:
- Sulfur
- Selenium
- Tellurium

Note:Although Dobereiner was successful in identifying the common properties between elements, it had some shortcomings as well. Some are mentioned below:
- The identification of new elements made his law of triads incapable and obsolete
 -Newly discovered elements had no place in the triads
- Only a total of 5 triads were able to be formed
- Some known elements at that moment couldn’t be grouped with the existing triads