Chapter 6.1, Problem 1SSC

Interpretation Introduction

Interpretation:

The contributions made by Lavoisier, Newlands, Mendeleev and Moseley in the periodic table needs to be described

Concept introduction:

To study the elements, classification of the elements is necessary. So, some of the scientists in the 18^th century began grouping the elements of similar characteristics. Lavoisier, Newlands, Mendeleev etc. are some of the scientist who gave their contribution to make the periodic table.

Answer to Problem 1SSC

Lavoisier groups the elements of that in four groups, Newlands gave the law of octaves, Mendeleev gave the first law of periodicity considering the atomic mass and Moseley gave the modern periodic law.

Explanation of Solution

In the late 1700, Lavoisier compiled a list of all elements that were known at that time. The list contained 33 elements categorized in four groups, gases, metals, non-metals and Earths.

In 1866, John Newlands proposed the law of octaves. According to this law, According to this law, on arranging elements in order of increasing atomic mass, every 8^th element possesses properties similar to first.

Mendeleev in 1869 published his theory for the formation of the periodic table. He gave a law which is Mendeleev periodic law. This law states that the elements are arranged in the periodic table in order of increasing atomic masses.

In 1913, the modern periodic law is proposed by Moseley, which states that physical and chemical properties of elements vary with the atomic number of the elements. So, elements are arranged in the periodic table in order of their increasing atomic numbers.

Conclusion

Earlier the arrangement of elements are based on their atomic masses but the later the modern periodic law given by Moseley, which is based on atomic number is accepted for constructing the modern periodic table.