Question

the electronic configuration of an element T is 2,8,7. 1) what is valency of t 2) is t is a metal pr non-metal​

Answer 1

Answer:

2,8,7 is the electronic configuration.

a)T can accept one electron to gain octet configuration.Hence, valency is -1.

b)It is a non-metal(halogen compound).

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Answer 2

Answer- The given question is from the chapter 'Periodic Classification of Elements'.

Valency: Valency is the combining capacity of an atom of an element.

The number of valence electrons help in determining valency.

Examples:

Sodium (Na) has atomic number 11 and its electronic configuration is 2, 8, 1.

Since Na can easily lose 1 electron to attain stability, it has valency +1. Thus, it is electropositive and is a metal.

Fluorine (F) has atomic number 9 and its electronic configuration is 2, 7.

Since F can easily gain 1 electron to attain stability, it has valency -1. Thus, it is electronegative and is a non-metal.

Metals have 1, 2, 3 as valent electrons. Therefore, their valency is +1, +2 and +3.

Non-metals have  5, 6, 7 as valent electrons. Therefore, their valency is -3, -2, -1. (Case is different for non-metals like: Carbon with tetravalency.)

Given question: The electronic configuration of an element T is 2,8,7.

1) What is valency of T?

2) Is T a metal or a non-metal?

Solution: For an element T,

Electronic Configuration = 2, 8, 7

1) We know that T can gain 1 electron to complete its valent shell rather than losing 7 electrons to complete the octet and attain stability.

So, valency of T= 1

2) We know that non-metals gain electrons. Since, T has gained one electron, therefore, it is a non-metal.

Conclusion:

1) Valency of T= 1

2) T is a non-metal.