First slide
Predicting position of element in modern periodic table
Question

An element with Z = 77 of modern periodic table belongs to same group as that of the element with Z = 

Moderate
Solution

Hints to predict the position of element in the Modern periodic table :

1)Elements from Z = 58-71……Lanthanoids…..4f series….6th period……3rd(IIIB) group;

2)Elements from Z = 90-103……Actinoids…..5f series….7th period……3rd(IIIB) group;

3)Elements from Z = 104-118………..Last two digits gives group number….. 7th period;

4)Elements from Z = 31-57….subtract 18 to get preceding element;

5)Elements from Z = 72-89….subtract 32 to get preceding element;

6)Elements from Z = 104-120….subtract 32 to get preceding element ;

For Z=104-120….simplest Hint

7)Elements from Z = 104-120….subtract 82 to get a lower member(Z<30) belonging to same group;

Hints 4, 5 and 6 can be used repeatedly until an element belonging to same group with Z < 30 is obtained;

Elements with Z < 30 with their group, period and block can be known from Electronic configuration;

Ex : Z=109, 77, 45, 27….belong to 9th(VIII) group;

(109-32)=77; (77-32)=45; (45-18)=27;

(n-1)d1-10ns1-2 ;

Note : Many elements of d-block have anomalous configuration. So only GEC of each group is highlighted;

Z = 27…….Co…  4s23d7…….n=4…..4th period…..d-block….…..9th group;

Z = 45…….Rh………….….….n=5….5th period……d-block……...9th group;

Z = 77…….Ir…………..………n=6….6th period……d-block…..…9th group;

Z = 109…..Mt…………..……..n=7…..7th period……..d-block..……..9th group;

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