Predicting position of element in modern periodic table
Question

# An element with Z = 81  belongs to ………block of modern periodic table

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=113, 81, 49, 31, 13, 5….belong to 13th(IIIA) group;(113-32)=81; (81-32)=49; (49-18)=31; (31-18)=13;Z = 13…..Al….3s23p1…..n=3….3rd period……p-block….valence electrons(3)….13th group;Z = 31…..Ga….4s24p1…..n=4….4th period……p-block….valence electrons(3)….13th group;Z = 49…..In….5s25p1…..n=5….5th period……p-block….valence electrons(3)….13th group;Z = 81…..Tl….6s26p1…..n=6….6th period……p-block….valence electrons(3)….13th group;Z = 113…..Nh….7s27p1…..n=7….7th period……p-block….valence electrons(3)….13th group;

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