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प्रश्न
What is Debereiner's law of triads? Explain with the help of one example of a Dobereiner's triad.
उत्तर
According to Dobereiner's law of triads, when elements are arranged in increasing order of their atomic masses, a group of three elements with similar chemical properties is obtained. This group is called a triad. The atomic mass of the middle element is equal to the arithmetic mean of the atomic masses of the other two elements.
For example, the set of elements: calcium (Ca), strontium (Sr) and barium (Ba), with atomic masses 40, 88 and 137 respectively form a triad because they have similar chemical properties, and the atomic mass of strontium is approximately equal to the average of the atomic masses of calcium and barium.
Arithmetic mean of atomic masses of calcium and barium =`(40+137)/2 =88.5`
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संबंधित प्रश्न
What were the limitations of Dobereiner’s classification?
The three imaginary elements X, Y and Z represent a Dobernener's triad. If the atomic mass of element X is 14 and that of element Y is 46, then the atomic mass of element Z will be:
(a) 28
(b) 60
(c) 78
(d) 72
In Dobereiner’s triads Li, Na, K, the atomic masses of Lithium and Potassium are 6.9 and 39.1 respectively, then what will be the atomic mass of sodium?
With an example, explain Dobereiner's Triads.
Can the following groups of elements be classified as Dobereiner's triad:
Be, Mg, Ca
Atomic mass of Be - 9, Mg - 24, Ca - 40.
Justify your answer.
Explain why Dobereiner’s method of classification of elements did not hold much weightage for future classification.
Dobereiner laid down the _______ rule.
According to Dobereiner’s triads rule, three elements in an increasing order of atomic mass shows _______.
In Dobereiner’s triads, the atomic weight of the middle element is ______ the of the atomic masses of 1st and 3rd elements.
Match the following.
| 1. | Triads | Newlands |
| 2. | Alkali metal | Calcium |
| 3. | Law of octaves | Henry Moseley |
| 4. | Alkaline earth metal | Sodium |
| 5. | Modern Periodic Law | Dobereiner |
