What is the basis of Mendeleev’s periodic law?

Mendeleev's periodic law is the fundamental principle that forms the basis of the modern periodic table of elements. It was proposed by Russian chemist Dmitri Mendeleev in 1869. The law states that the properties of elements are a periodic function of their atomic masses. In other words, when elements are arranged in order of increasing atomic masses, their properties repeat in a regular pattern.

Key points of Mendeleev's periodic law include:

Elements are arranged in increasing order of atomic masses: Mendeleev listed the known elements of his time in order of increasing atomic masses, similar to how they are organized in the modern periodic table.

Periodic repetition of properties: Mendeleev noticed that elements with similar chemical and physical properties occurred at regular intervals. This repetition forms what is known as "periods" in the periodic table.

Grouping elements with similar properties: Mendeleev grouped elements with similar properties into vertical columns, which are now called "groups" in the modern periodic table.

Gaps in the table: While organizing the elements, Mendeleev also noticed that some places in the table were empty, suggesting that there were yet-to-be-discovered elements. He even predicted the properties of these unknown elements, and many of his predictions were later confirmed with the discovery of new elements.

Mendeleev's periodic law laid the foundation for the development of the modern periodic table, which has evolved over time to include new elements and has been further refined based on atomic number instead of atomic mass. The modern periodic table not only arranges elements by increasing atomic number but also provides additional information about the elements' electron configurations, chemical properties, and relationships between elements.