Explain vakency with suitable example

The first 20 elements of the periodic table :

1.H —Hydrogen

2.He—Helium

3.Li—Lithium

4.Be—Beryllium

5.B—Boron

6.C—Carbon

7.N—Nitrogen

8.O—Oxygen

9.F—Fluorine

10.Ne—Neon

11.Na—Sodium

12.Mg—Magnesium

13.Al—Aluminum

14.Si—Silicon

15.P—Phosphorus

16.S—Sulfur

17.Cl—Chlorine

18.Ar—Argon

19.K—Potassium

20.Ca—Calcium

The valency of first 20 elements is as follows :-

1. Hydrogen (H) = 1

2. Helium (He) = 0

3. Lithium (Li) = 1

4. Beryllium (Be) = 2

5. Boron (B) = 3

6. Carbon (C) = 4

7. Nitrogen (N) = 3

8. Oxygen (O) = 2

9. Fluorine (F) =1

10. Neon (Ne) = 0

11. Sodium (Na) = 1

12. Magnesium (Mg) = 2

13. Aluminium (Al) = 3

14. Silicon (Si) = 4

15. Phosphorus (P) = 3, 5

16. Sulphur (S) = 2

17. Chlorine (Cl) = 1

18. Argon (Ar) = 0

19. Potassium (K) = 1

20. Calcium (Ca) = 2

Explanation:

First 20 elements in the periodic table start with H and end with Ca. The quickest way to remember the number of valence electrons is to form a relationship with the number of the group the element is located in.

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