Question

What do you mean by dobereiner triad , Newland law of octave and explain their limitations (3 mark questions) good answer will be Mark as brainliest

Answer 1

Definitions :

Dobernier's Law of triads is the law which states that "when elements are arranged in increasing order of their atomic weights , they form groups of three called triads in which the atomic weight of the middle element is generally found to be the mean or arithmetic average of the other two elements."

Newland's Law of Octaves states that " when elements are arranged in increasing order of their atomic weights , they form groups of eight in which the properties of the first element is similar to the properties of the eighth element which is the same as that of a musical note ".

Limitations :

Dobereneir's law of triads is discarded since method did not hold true for all elements.

Newland's Law of Octaves failed to leave space for undiscovered elements.

Answer 2

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$\bold{a)\:Dobereiner\:triad:-}$


=> Dobereiner found some groups of three elements which showed similar properties.


=> These groups were called as triads.


=> In these triads, atomic mass of the middle element is approximately equal to the mean of other two elements.


=> Also these elements shows similarities in properties.


$\bold{Limitations:-}$


(i) All known elements could not be classified into groups of triads.


(ii) Not all groups obeyed the Law of Triads.


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$\bold{b)\:Newlands\:law\:of\:octaves:-}$


=> Newlands arranged the elements in the order of increasing atomic masses.


=> He started with the element having the lowest atomic mass.


=> And, he ended at thorium which was the 56th element.


=> He found that every eighth element had properties similar to that of the first, like the octaves found in music.


=> He called this the ‘Law of Octaves’.


$\bold{Limitations:-}$


(i) This law was applicable only upto calcium.


(ii) It was not applicable to elements of higher atomic mass.


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