Same chapter3 marksDifficulty: Medium
State two advantages of the modern periodic table over Mendeleev's table.
The Periodic Table
2 marksDifficulty: Easy
State Mendeleev's periodic law and the modern periodic law, and say why the law was changed.
Original Khojo Papers practice question — not from a past board paper.
Answer
Mendeleev's law stated that the properties of elements are a periodic function of their atomic masses. The modern law states that they are a periodic function of their atomic numbers. The change was made because certain pairs, such as argon and potassium, had to be placed out of order of atomic mass to fit their properties, and the anomaly disappears when atomic number is used.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
The atomic number was shown by Moseley to be the fundamental property of an element.
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