Question

Explain the Modern Periodic Law , also define salient features of modern periodic table

Answer 1

Ans : Modern Periodic Law :
Based on the concept of atomic number Bohr , Werner & Bury proposed the modern periodic law as ;
“The physical & chemical properties of all elements are periodic functions of their atomic numbers.”
It is also known as Bohr’s Long Form Of Periodic Table.
Salient features of the Modern Periodic Table :
Groups :
The vertical columns are called groups. In periodic table there are basically eight groups which are further subdivided into Sub group A & B & so total 16 groups. Sub group A represents “Main or Representative elements “ while Sub group B represents “Transition elements”. The group number indicates the total number of electrons in valency shell of that element.
Periods :
The horizontal columns are called periods. In periodic table there are seven periods. The physical & chemical properties of elements change from metallic to non metallic along a period.