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Questions
What were the limitations of Dobereiner’s classification?
State limitations of Dobereiner's law of triads?
Solution
- All known elements could not be classified into groups of triads on the basis of their properties.
- Dobereiner could find only three triads; .i.e total of 9 elements only.
- However, the total number of elements was more than that of those encompassed in Dobereiner’s Triad.
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RELATED QUESTIONS
Did Dobereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
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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
The atomic masses of three elements X, Y and Z having similar chemical properties are 7, 23 and 39 respectively.
(a) Calculate the average atomic mass of elements X and Z.
(b) How does the average atomic mass of elements X and Z compare with the atomic mass of element Y?
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Give reason for your answer.
(Atomic masses : Be 9 ; Na 23 ; Mg 24 ; Si 28 ; Cl 35.5 ; Ca 40)
In Dobereiner’s triad containing Li, Na, K, if atomic masses of Lithium & Potassium are 6.9 and 39.1, then what will be the atomic mass of Sodium?
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?
A, B and C are the elements of a Dobereiner's triad. If the atomic mass of A is 7 and that of C is 39, what should be the atomic mass of B?
Why was Dobereiner's triad discarded?
Did Dobereiners triads also exist in the columns of Newland's Octaves? Compare and find out.
Can the following groups of elements be classified as Dobereiner's triad:
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Atomic mass of Na - 23, Si - 28, Cl - 35.
Justify your answer.
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.
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State Dobereiner’s Law of Triads with suitable examples.
Dobereiner laid down the _______ rule.
Find the odd one out and give its explanation.
Find the odd one out and give its explanation.
Write the name.
The atom having the biggest atomic size from period 2.
In Dobreiner's triads, three elements appear to be arranged in ascending order of their atomic number.
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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 |
Can the following groups of elements be classified as Döbereiner's triad?
- Na, Si, Cl
- Be, Mg, Ca
Atomic mass of Be 9; Na 23; Mg 24; Si 28; Cl 35; Ca 40 Explain by giving reason.
