All questions of Introduction to Chemistry for Class 6 Exam

Significant Contribution of Dmitri Mendeleev
Dmitri Mendeleev, a Russian chemist, made one of the most significant contributions to the field of chemistry by creating the modern periodic table. His work laid the foundation for understanding the relationships between various elements.
Development of the Periodic Table
- Mendeleev published the first version of the periodic table in 1869.
- He arranged the elements in order of increasing atomic mass, which highlighted patterns in their properties.
Key Features of Mendeleev's Periodic Table
- Periodic Law: Mendeleev proposed that the properties of elements are a periodic function of their atomic masses.
- Grouping Elements: He grouped elements with similar chemical properties into vertical columns, known as groups.
- Prediction of Missing Elements: Mendeleev left gaps for undiscovered elements and accurately predicted their properties based on the patterns he observed. For instance, he predicted the existence of gallium and germanium.
Impact on Chemistry
- Mendeleev's periodic table helped scientists organize and categorize elements, making it easier to study their behaviors and properties.
- His work paved the way for future developments in chemistry, including the modern periodic table, which is organized by atomic number instead of atomic mass.
In summary, Mendeleev's creation of the modern periodic table was a groundbreaking advancement that transformed the understanding of chemical elements and their interactions, establishing a systematic approach that is still used in chemistry today.