Question

what does first and second series mean in mendeleevs periodic table and what does A and B in the groups of mendeleeves periodic table mean??

Answer 1

PART : I
The first and second series mean elements present in different periods horizontally transition elements in mendeleevs periodic table.

First series

K=39

Ca=40

Sc=45

Ti=48

V=51

Cr=52

second series

Cu =63

Zn= 65

Ga=70

Ge= 73

As=75

Se=79

PART : II
A represents the group that include in the s- or p-block elements
B represents the group that include the d-block elements