Question

AN ANYONE GIVE ME ALL DRAWBACKS AND CONTRIBUTION OF DOBEREIGNER , NEWLAND AND MENDELEEV . I WILL MARK BRAINLIEST PLUS GIVE ALL MY POINTS . BUT I NEED BOTH DRAWBACKS AND CONTRIBUTION OF ALL PERSONS ..

Answer 1

DOBREINEIR'S TRIADS :

advantages=1.mass of middle element was roughly avg. atomic mass of other 2 elements.

disadvantage=1.he could identify only 3 TRIADS

Answer 2

DOBERENIER'S TRAIDS

_Contributions:

He arranged the elements with similar properties in a group of three known as triads in such a manner that the atomic masses of the middle element was approximately the average of the other two elements.

Eg: lithium, sodium and potassium .

_limitations:only three triads were identified from the element known at that time has this classification was not useful.

NEWLAND'S LAW OF OCTAVES

_ contribution:

-He arranged the elements in the order of increasing atomic masses starting with hydrogen and ended with thorium having atomic mass of 56.

according to him the properties of every 8th element was similar to the first element.

And it was compared to the music notations sa ,re ,ga ,ma, pa, da, Ni, sa and does the name newlands law of octaves.

_ limitations:

1.the newland law of octave was applicable only for lighter element having atomic mass up to 40 that is up to calcium.

2.he believed that only 56 element existed in the nature but later or more elements are discovered whose properties did not fit into newlands law of octaves

3.some elements having different properties were grouped together like Cobalt and nickel having been placed with halogens.

MENDELEEV'S PERIODIC TABLE

_ contribution:

--Mendeleev periodic law states that the properties of elements are the periodic functions of their atomic masses

--He arranged the elements in order of increasing atomic masses ,similarity in physical and chemical properties of element, properties of hydrides and oxides of different element was studied and elements with similar properties were group together.

--He classified the elements in table consisted of vertical columns called groups and horizontal rows call periods.

Merits:

--He left some blank spaces for an discovered elements

--The noble gases which was discovered later could be played without disturbing the existing order

-- He predicted the discovery of some elements and name them as eka boron, eka aluminium and eka silicon.

Limitations:

--Position of hydrogen was not assign properly as hydrogen resembles alkali metals as well as halogens.

--no separate position has been given two isotopes of an element .

isotopes are placed in the same position though they have a different atomic masses.

--some element having higher atomic masses are placed before the element with lower atomic masses