# Answer the following question. For s-block and p-block elements show that the number of valence electrons is equal to its group number. - Chemistry

For s-block and p-block elements show that the number of valence electrons is equal to its group number.

#### Solution

1. 3Li is an s-block element and its electronic configuration is 1s2 2s1. Since it has one valence electron, it is placed in group 1.
2. Therefore, for s-block elements, group number = number of valence electrons.
3. However, for p-block elements, group number = 18 – number of electrons required to attain complete octet.
4. 7N is a p-block element and its electronic configuration is 1s2 2s2 2p3. Since it has five electrons in its valence shell, it is short of three electrons to complete its octet.
5. Therefore, its group number = 18 – 3 = 15.
Concept: Periodic Table and Electronic Configuration
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#### APPEARS IN

Balbharati Chemistry 11th Standard Maharashtra State Board
Chapter 7 Modern Periodic Table
Exercises | Q 5. (G) | Page 109