Difference Between Mendeleev and Moseley Periodic Table

Key Difference – Mendeleev vs Moseley Periodic Table
 

The periodic table of elements is the arrangement of all the known chemical elements in a table that represent their periodic trends. The chemical elements are arranged based on their atomic numbers. These chemical elements can be categorized in different ways; as metals, non-metals and metalloids, s block, p block and d block elements. The very first organized periodic table was proposed by Mendeleev in 1869. But the modern periodic table that we use was proposed by Henry Moseley in 1913. The key difference between Mendeleev and Moseley periodic table is that Mendeleev periodic table is created based on the atomic masses of chemical elements whereas Moseley periodic table is created based on the atomic numbers of chemical elements.

CONTENTS

1. Overview and Key Difference
2. What is Mendeleev Periodic Table
3. What is Moseley Periodic Table
4. Side by Side Comparison – Mendeleev vs Moseley Periodic Table in Tabular Form
5. Summary

What is Mendeleev Periodic Table?

Mendeleev Periodic Table was proposed by Dimitri Mendeleev in 1869. It was a tabular arrangement of chemical elements based on their atomic masses. This periodic table also indicated that there are relationships between chemical and physical properties with the atomic mass of chemical elements. In his periodic table, chemical elements with similar properties were in the same vertical columns.

In that time, there were only 56 known elements. The first and foremost periodic table created by Mendeleev was a very small table containing only 9 chemical elements. then he proposed the extended periodic table with some gaps in periods “horizontal rows”. He assumed that those chemical elements have not been discovered yet.

Apart from that, Mendeleev attempted to determine the atomic masses of missing chemical elements and to predict their properties. Most of the chemical elements he predicted were turned to be correct after the discovery of them.

What is Moseley Periodic Table?

The well-organized periodic table containing chemical elements arranged based on their atomic numbers was first proposed by Henry Gwyn Jeffreys Moseley in 1913. This periodic table shows the following groups;

• Alkali metals (group 1)
• Halogens (group 7)
• Noble gases (group 8)
• Transition metals

Before this prediction, the atomic number of a chemical element was considered as a semi-arbitrary number that is sequential based on the sequence of atomic mass. But the discovery of Henry Moseley demonstrated that the atomic number is not just an arbitrary number, it has a strong experimental basis of physics.

What is the Difference Between Mendeleev and Moseley Periodic Table?

Mendeleev vs Moseley Periodic Table
Mendeleev Periodic Table was proposed by Dimitri Mendeleev in 1869.	The well-organized periodic table containing chemical elements arranged based on their atomic numbers was first proposed by Henry Gwyn Jeffreys Moseley in 1913.
Arrangement
The Mendeleev periodic table has chemical elements arranged based on their atomic masses.	The Moseley periodic table has chemical elements arranged based on their atomic numbers.
Composition
Mendeleev periodic table had only 56 chemical elements.	Moseley periodic table had 74 chemical elements.

Summary – Mendeleev vs Moseley Periodic Table

The development of modern periodic table was not a single step development and it has many improvements time after time. The first well-arranged periodic table was proposed by Dimitri Mendeleev in 1869. Then the key to the modern periodic table was proposed by Henry Moseley in 1913. The difference between Mendeleev and Moseley periodic table is that Mendeleev periodic table is created based on the atomic masses of chemical elements whereas Moseley periodic table is created based on the atomic numbers of chemical elements.

Reference:

1.“Periodic table.” Wikipedia, Wikimedia Foundation, 25 Feb. 2018. Available here 
2.Moseley’s Periodic Table. Available here   
3.“Henry Moseley.” Wikipedia, Wikimedia Foundation, 20 Feb. 2018. Available here

Image Courtesy:

1.’Dmitri Mendeleev’By unknown (Public Domain) via Commons Wikimedia