The Modern Periodic Table

The modern periodic table is a classification of elements based on their increasing atomic numbers. This arrangement allows for a more accurate prediction of element properties, making it an improvement over Mendeleev’s Periodic Table. It is also referred to as the Long Form of the Periodic Table.

Features of the Modern Periodic Table:

• Elements are arranged by atomic number, eliminating most of the drawbacks of Mendeleev’s table.
• Electronic configuration is directly linked to atomic number, providing a clear periodic trend.
• Ambiguity about hydrogen’s position remains unresolved.

Henry Moseley’s Contribution (1913):

Conducted X-ray experiments and found that the square root of X-ray frequency is directly proportional to the atomic number of an element. This proved that atomic number is a fundamental property, leading to the formulation of Modern Periodic Law: "The physical and chemical properties of elements are periodic functions of their atomic numbers."

This discovery led to the modification of Mendeleev’s Periodic Law, adopting atomic number as the basis of classification.

Advantages of the Modern Periodic Table:

• More precise prediction of element properties.
• Systematic arrangement based on atomic number removes inconsistencies.
• Clearer relation between atomic number and electronic configuration enhances understanding of periodic trends.