Question

can any body tell me how to find valancy

Answer 1

hello here is your answer ..

$<b><i><u>To tell you I am taking example of magnesium </b></i></u>$

$<b><i><u> see as we know that magnesium comes on 12 the number in the periodic table </b></i></u>$

◆◆And now ,
as we know that the first shell is having the total capacity to take 2 electrons and second shell is having the total capacity to take 8 electrons ◆◆

now what is valeced shell?

$<b><i><u> The outermost shell is called the valences shell </b></i></u>$

➡so now raise to your question how to calculate the valecy ?
$<b><i><u> so the number of electrons contained in the outermost shell of the atom is called it's valencey </b></i></u>$

so now we represent magnesium as shells ...

There is distribution of electrons in four cells that we represent as K L M N

➡Now in the first shell there are total 2 electrons i.e. in k as I tell you first .

➡And in second shell there are total 8 electrons as I tell you first .

➡so now there must be 2 cells in the outer because it's total no. of electrons is 12 as it's on 12th number in periodic table and 2 and 8 electrons are carried by first and second shell so 12-10 = 2..

as I tell you in first that the number of electrons in the outermost shell is called it's valencey ..

➡ so it's electronic configuration is 2,8,2 and there are 2 electrons its outer shell so it's valecy is 2..

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And now I would like to tell you how to determine its charge ..
so here we go ➡

see there are 2 electrons in outer shell and it is not possible to take 6 electrons from anywhere maximum to maximum it can take 3 or 4 electrons ..

but it can remove 2 electrons to become stable . And after removing it . it's become stable and no need for further any electrons .

$<b><i><u> And remember one thing that if it removes electron then their is 'positive'charge and if it takes atom then their is ' negative ' charge </b></i></u>$

so here it is removing so magnesium charge is "posotive"
so here the magnesium charge comes as 2+

And we represent magnesium as Mg^2+

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$\mathfrak{\huge{\blue{hope \:it \:helps\: you }}}$