Mendeleev Periodic Table vs. Modern Periodic Table

Attribute	Mendeleev Periodic Table	Modern Periodic Table
Creator	Dmitri Mendeleev	Various scientists contributed to its development
Arrangement	Arranged elements by increasing atomic mass	Arranged elements by increasing atomic number
Number of elements	63 known elements	118 known elements
Periods	7 periods	7 periods
Groups	8 groups	18 groups
Use of atomic mass	Used atomic mass to predict properties of missing elements	Atomic mass is not used for arrangement

Introduction

The periodic table is a tabular arrangement of the chemical elements, organized by their atomic number, electron configuration, and recurring chemical properties. The two most well-known versions of the periodic table are the Mendeleev Periodic Table and the Modern Periodic Table. While both tables serve the same purpose of organizing elements, they have some key differences in their attributes and organization.

History and Development

The Mendeleev Periodic Table was created by Russian chemist Dmitri Mendeleev in 1869. Mendeleev arranged the elements in order of increasing atomic weight and grouped them based on their chemical properties. He left gaps in the table for elements that had not yet been discovered, predicting their properties based on the trends he observed. In contrast, the Modern Periodic Table was developed by Henry Moseley in 1913. Moseley arranged the elements by increasing atomic number, which led to a more accurate organization of the elements based on their properties.

Organization of Elements

In the Mendeleev Periodic Table, elements were arranged in rows and columns based on their atomic weight and chemical properties. Mendeleev also grouped elements with similar properties into columns, known as groups. The Modern Periodic Table, on the other hand, organizes elements by increasing atomic number and groups them based on their electron configuration and chemical properties. This arrangement allows for a more accurate prediction of an element's properties based on its position in the table.

Periods and Groups

Both the Mendeleev Periodic Table and the Modern Periodic Table have periods and groups that help to organize the elements. In the Mendeleev Periodic Table, there were eight groups, with elements in each group having similar chemical properties. The Modern Periodic Table has 18 groups, which are arranged based on the number of valence electrons in the outer shell of the elements. The periods in both tables represent the number of electron shells an element has, with each period corresponding to a new energy level.

Properties of Elements

One of the key differences between the Mendeleev Periodic Table and the Modern Periodic Table is how they predict the properties of elements. Mendeleev's table was able to predict the properties of undiscovered elements based on the trends he observed in the known elements. This predictive power was a significant achievement at the time. The Modern Periodic Table, with its more accurate arrangement based on atomic number, allows for a more precise prediction of an element's properties based on its position in the table.

Use in Chemistry

Both the Mendeleev Periodic Table and the Modern Periodic Table are essential tools in the field of chemistry. They provide a systematic way to organize the elements and predict their properties. The Modern Periodic Table is more widely used today due to its accuracy and ability to predict the behavior of elements more effectively. However, Mendeleev's table laid the foundation for the development of the modern table and remains an important part of the history of chemistry.

Conclusion

In conclusion, the Mendeleev Periodic Table and the Modern Periodic Table are both important tools for organizing the elements and predicting their properties. While Mendeleev's table was groundbreaking in its time and laid the foundation for the modern table, the Modern Periodic Table is more accurate and widely used today. Both tables have their own attributes and organization methods, but they ultimately serve the same purpose of helping chemists understand the behavior of the elements.