Question

an element has same electron in 1st and 2nd shells as in 3rd and 4th shells

1) write down the electronic configuration of the element
2) valency
3) group no. and period to which it belongs

Answer 1

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TᕼE ᗩᑎᔕᗯEᖇ Iᔕ " Bྂeྂrྂyྂlྂlྂiྂuྂmྂ "

the beryllium contains 4 electrons so it's electronic configuration becomes..

1s(2) , 2s(2)

so 2 electrons are present in both the 1st and 2nd shell

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Answer 2

●The element which has same electron in its 1st and 2nd shell is ... Be (beryllium )

•its electronic configuration is (2 ,2 )

•its valency is 2

• group number is 2 and period is also 2 ....

● the element which has same electron in its 3rd and 4th shell is ..

Fe ( iron )

•its electronic configuration is (2,8,8,8)

•its valency is 2 and 3 .... { NOTE : valency of d block varies }

•its group number is 8 and period number is 4 ....

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