Question

how to find which group or period of the element

Answer 1

$\huge\purple{As-Salamu-Alykum}$


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Its pretty much easier to find which group or period an element belongs to ...


If......


Their Electronic configuration is known .

$\huge\red\bold{Example :}$

For example an element has electronic configuration :-

Outer electron is in :-

4s1

-•-

So........


This 4 represent Period in which this element is present


And.....

1 is the group that is it belongs to group 1

The digit on left side of a subshell shows period and that on right side shows group.

So Periods will be 7 and groups will be 8 (Complete octet )


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$\huge\orange{INSHALLAH it will help U}$

Answer 2

.      The period of element relates the number of shells of an atom of the given element.

    2.      The group is similar to the no of valence electrons of given element.

   3.      The valency is the no of electrons it accepts or donates. So in case of non-metals        valency = 8-valence electrons & in case of metals valency=valence electrons... This is B’COZ  non-metals accept so lacked electrons only considered.

    4.      The number of element in each period is calculated by 2n2.

                                                                             

   Steps to find the position of an non-transitional element in periodic table

    1.      First take the Atomic number of the given element. Say Cl... Atomic no. 17

    2.      Then calculate the electronic configurationusing the atomic number 2+8+7=17 therefore the electronic configuration will be 2, 8, 7.

    3.      Here we find that the no of valence electrons of element is 7 as the valence shell has 7 electrons.

    4.      So know we easily understand that the group is 7 because the no of valence electrons is 7.

    5.      Now to find the period we have to understand that the period is the number of shellthe element is having therefore here chlorine has 3 shells (K-2, L-8, and M-7). So the period of the given element is 3.

Thus the position of the given element (here chlorine) is …..

Group

VII A (17th)

B’COZ VALENCE ELECTRONS = 7

Period

3rd

B’COZ NO OF SHELLS = 3

 

NB: Valency 8 refers to the group 0 and the element must be a Noble Gas.