Question

.The electronic configuration of an element T is 2, 8,
8, 1.
(i) What is the group number of T?
(ii) What is the period number of T?
(ii) How many valence electrons are there in an atom
of T ?
(iv) What is the valency of T?
(v) Is it a metal or a non-metal?
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Answer 1

Answer:-

Given:-

Electronic configuration of an element T : (2 , 8 , 8 , 1) i.e., T - 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹

i) Group number is equal to the number of electrons filled in the last shell.

In the element T, 1 electron is filled in the last shell.

So, T belongs to 1st or I A group.

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ii) Period number is equal to the shell number (higher n value) where the differentiating electron (last electron) is present.

In T , The last electron is present in 4s orbital. The value of n in 4s orbital is 4

So, T belongs to 4th period.

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iii) Valence electrons are nothing but the electrons present in the last shell.

The last shell in T is 4th shell. And it has 1 electron in s - orbital.

So, There is 1 Valence electron in T.

___________________________

iv) Valency is the combining capacity of an element. It is equal to the number of Valence electrons (only if no.of Valence electrons < 4).

In T , there is only 1 Valence electron.

Hence, Valency of T is 1.

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v) We know, If an element has valency < 3 , then it is a metal and if it has valency ≥ 3 , it is a non metal.

Valency of T is 1 and 1 < 3.

So, T is a metal.

Answer 2

Answer:

Given :-

$\mapsto$ The electronic configuration of an element T is 2 , 8 , 8 , 1.

To Find :-

• What is the group number of T.
• What is the period number of T.
• How many valence electrons are there in an atom of T.
• What is the valence of T.
• Is it a metal or non-metal.

Solution :-

$\bigstar$ (i) What is the group number of T :

$\implies$ The number of electrons in the outer most shells is n = 4 is 1.

So, it is belong to the group no 1.

$\rule{150}{2}$

$\bigstar$ (ii) What is the period number of T :

$\implies$ The number of electrons in the outer most shells is 4.

So, it has a period number of T is 4.

$\rule{150}{2}$

$\bigstar$ (iii) How many valence electrons are there in an atom of T :

$\implies$ It has only one electrons in the outer most shells.

So, there are only one valence electron.

$\rule{150}{2}$

$\bigstar$ (iv) What is the valency of T :

$\implies$ As it is T need to lose one electron to complete it's octet.

So, the valency of T is 1.

$\rule{150}{2}$

$\bigstar$ (v) Is it a metal or non-metal :

$\implies$ As it is has only one electrons in the outer most shells.

So, it is a metal.

$\rule{150}{2}$

EXTRA INFORMATION :

➲ Groups and their names :

1) Group-1 elements ➠ Alkali Metals

2) Group-2 elements ➠ Alkali earth metals

3) Group-11 elements ➠ Coinage metals

4) Group-15 elements ➠ Pnictogens

5) Group-16 elements ➠ Chalcogens

6) Group-17 elements ➠ Halogens

7) Group-18 elements ➠ Noble Gases