Postulates of Mendeleev Periodic Table

Mendeleev's periodic table is a tabular arrangement of the elements in order of their increasing atomic masses. The postulates of Mendeleev's periodic table are as follows:

• Periodic Law: The physical and chemical properties of elements are periodic functions of their atomic masses.


• Elements are arranged in order of their increasing atomic masses: Mendeleev arranged the elements in rows and columns based on their atomic masses.


• Periodicity: The properties of the elements repeat in a periodic manner.


• Grouping: Elements with similar properties are grouped together in the same column.


• Prediction of new elements: Mendeleev left gaps in his periodic table for elements that were yet to be discovered. He predicted the properties of these elements based on the properties of the elements in the same group.

Explanation of the Postulates of Mendeleev Periodic Table

Periodic Law: The periodic law states that the physical and chemical properties of elements are periodic functions of their atomic masses. This means that as the atomic mass of an element increases, its properties will repeat in a periodic manner. For example, the properties of lithium, sodium, and potassium are similar because they are in the same group and have similar atomic structures.

Elements are arranged in order of their increasing atomic masses: Mendeleev arranged the elements in rows and columns based on their atomic masses. He noticed that elements with similar properties tended to have similar atomic masses, and he used this observation to organize the elements into a periodic table.

Periodicity: The periodicity of the elements refers to the fact that their properties repeat in a periodic manner. For example, the elements in Group 1 (the alkali metals) all have similar properties such as being highly reactive and having a single valence electron.

Grouping: Elements with similar properties are grouped together in the same column. Mendeleev grouped the elements into eight groups based on their properties, and these groups are still used in the modern periodic table.

Prediction of new elements: Mendeleev left gaps in his periodic table for elements that were yet to be discovered. He predicted the properties of these elements based on the properties of the elements in the same group. The discovery of new elements, such as gallium and germanium, confirmed Mendeleev's predictions and helped to establish the periodic table as a fundamental tool in chemistry.