Question

Classification of elements
pes of elements?
3. What are the smallest particles of matter called?
4. What is the difference between the molecules of elements and
compounds
We have learnt in the previous standards that all the atoms of an element are of only
one type. Today 118 elements are known to the scientific world. However, around year
1800 only about 30 elements were known. More number of elements were discovered in
the course of time. More and more information about the properties of these elements was
gathered. To case the study of such a large number of elements, scientists started studying
the patter if any, in the vast information about them. You know that in the initial
classification elements were classified into the groups of metals and nonmetals. Later om
another class of elements called metalloids was noticed. As the knowledge about elements
and their properties went on increasing different scientists started trying out different
methods of classification
Dobereiner's Triads
In the year 1817 a German scientist Dobereiner suggested that properties of elements
are related to their atomic masses. He made groups of three elements each, having similar
chemical properties and called them triads. He arranged the three elements in a triad in an
increasing order of atomic mass and showed that the atomie mass of the middle element
was approximately equal to the mean of the atomic masses of the other two
However, all the known elements could not be classified into the Dobereiner"​

Answer 1

Answer:

Classification of elements - metals and non- metals in earlier times

3. What are the smallest particles of matter called?

Atom

4. What is the difference between the molecules of elements and compounds

elements are made up of pure atoms while compounds are made up of two different atoms.

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