Question

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Class 9th
Ch - Structure Of The Atom
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Answer 1

Answer

The valency of both the elements are:

• Nitrogen (N) = -3
• Chlorine (Cl) = -1

Step-by-step Explanation

What is valency?

Valency is known as the combining power of an element. The valency of an element is related to how many electrons are in the outer shell.

Findind valency of given elements:

• Nitrogen (N)

For finding valency, we will first make their electronic configuration. As the Atomic Number (Z) is less than 20, we will configure it as- 2,8,8.

⇛ Nitrogen (N) Atomic number = 7

⇛ Electronic configuration = 2,5

Now, we will find the valency of electrons in outer shell.

⇛ Valency = 8-5

⇛ Valency = 3

As it gains electrons in outer shell, the valency will be-

⇛ Valency = -3

• Chlorine (Cl)

Same here, for finding valency, we will first make their electronic configuration. As the Atomic Number (Z) is less than 20, we will configure it as- 2,8,8.

⇛ Clorine (Cl) Atomic Number = 17

⇛ Electronic configuration = 2,8,7

Now, we will find the valency of electrons in outer shell.

⇛ Valency = 8-7

⇛ Valency = 1

As it gains electrons in outer shell, the valency will be-

⇛ Valency = -1

Answer 2

The valency of Nitrogen and Chlorine is 3- and 1-.

This is because,

Atomic number of N = 7

So, electronic configuration is 2, 5 (by 2n²).

∴ Valency = 8 - 5 = 3.

Atomic number of Cl = 17

So, electronic configuration is 2, 8, 7.

∴ Valency = 8 - 7 = 1.