Q. Which of the following is not based on atomic mass?
- Dobereiner triads
- Newland's law of octaves
- Mendeleev classification
- Modern periodic table
Select the correct answer from the codes given below:
Answer:
Only 4
Notes: Döbereiner showed that when the three elements in a triad were written in the order of increasing atomic masses; the atomic mass of the middle element was roughly the average of the atomic masses of the other two elements. In 1866, John Newlands, an English scientist, arranged the then known elements in the order of increasing atomic masses. He started with the element having the lowest atomic mass (hydrogen) and ended at thorium which was the 56th element. When Mendeléev started his work, 63 elements were known. He examined the relationship between the atomic masses of the elements and their physical and chemical properties. Mendeléev's Periodic Law was modified and atomic number was adopted as the basis of Modern Periodic Table and the Modern Periodic Law can be stated as follows: 'Properties of elements are a periodic function of their atomic number.’