Write the contribution of Mendeleef in the creation of the ‘periodic table’. [3]
OR
What is meant by the atomic radius of an atom? Arrange the first three elements C, Si and Ge of group 14 of long periodic table in the order of their increasing atomic radii. [2 + 1]
WBBSE
Class X
Physical Science
Periodic Table
03 Mark
2023
Mendeleev’s contributions to the creation of the periodic table include:
- Periodic Law: He arranged elements in order of increasing atomic mass and discovered that elements with similar properties appeared at regular intervals (periodicity).
- Predictions: Mendeleev left gaps in the table for undiscovered elements and accurately predicted their properties, such as gallium and germanium.
- Grouping of Elements: He successfully grouped elements with similar chemical properties into columns, establishing the foundation for the modern periodic table.
OR
The atomic radius of an atom is the distance from the center of the nucleus to the outermost shell of electrons. It represents the size of the atom.
For group 14 elements (C, Si, Ge):
C < Si < Ge
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