Science, asked by ashutosh6557, 11 months ago

There were 63 known elements that Mendeleev included in his periodic table excluding eka-Boron,eka-aluminium,eka-silicon. Hence, total number of elements should be 63 but in NCERT total number of elements is 63 even after including scandium (eka-Boron), aluminum (eka-aluminium), silicon (eka-silicon),how is it possible?​

Answers

Answered by perfect2003
1
Elements are arranged in the periodic table in the increasing order of their relative atomic masses.

Mendeleev divided his periodic table in eight groups and seven periods.

Groups from I to VII are meant for normal elements and group VIII is for transition elements.

Groups from I to VII have been divided in two sub groups, while group VIII is meant for three elements.

Periods from 4th to 7th have been divided in two series: 1st series and 2nd series.

Elements having similar properties have been kept in the same group. For example; lithium, potassium, rubidium, etc. are in 1st group.

Two general formulae; one for oxides and second for hydrides; have been given for the elements of each group in the periodic table. For example: R2O for oxides and RH for hydrides, of the elements; of 1st group.

Using the given general formulae; the formula of oxides and hydrides can be written for the elements of each group. For example; hydrogen, sodium, potassium, etc. belong to the first group. The general formula of oxides for the elements of 1st group is R2O. Accordingly they form H2O, Na2O, K2O, etc.


ashutosh6557: I know this and this wasn't the answer I was looking for anyways thanks for answering.
Answered by rajesh460
0
those elements were not known at that time and were not discovered.mendeleev predicted the properties of the elements by referring the properties of other elements in his perioddic table

ashutosh6557: sorry Rajesh this wasn't the answer I was looking for.
rajesh460: what is the problem with this answer
ashutosh6557: Actually my question was there were 63 known elements when Mendeleev formed his table right?
ashutosh6557: but scandium gallium and germanium weren't known by then
ashutosh6557: so if we disclude these three elements and count rest of the elements in his table then it should be 63
ashutosh6557: but in NCERT book's table if we don't include these elements then Total no' of elements are 60 that's my question!
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