Predicting position of element in modern periodic table
Question

# An element with Z = 42 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 Hint7)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=106, 74, 42, 24….belong to 6th(V1B) group;(106-32)=74; (74-32)=42; (42-18)=24;(n-1)d1-10ns1-2 ;Note : Many elements of d-block have anomalous configuration. So only GEC of each group is highlighted;Z = 24…….Cr…  4s13d5….….n=4…..4th period……d-block….….6th group;Z = 42…….Mo………….….….n=5….5th period……d-block……...6th group;Z = 74…….W…………..………n=6….6th period……..d-block…..……6th group;Z = 106….Sg…………..……n=7…..7th period……d-block..……. 6th group;

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