Question

Answer the following question:
Q#1. Define valency. Explain its types with examples.
Q#2. How does an element show positive and negative valencies.
Q#3. Calculate the valencies of first twenty elements.

Answer 1

Answer:

Valency of an element is the combining capacity of the atoms of the element with atoms of the same or different elements. There are two types of valency : Electrovalency and covalency

The valency of an element is either negative or positive. When an element having 1,2,3 electrons in its outermost shell tends to obtain nearest inert gas configuration it will loose these valence electrons and form a cation. Then its valency is positive. ... Then its valency is said to be negative.

Valency of first 20 elements

Hydrogen (H) = 1.

Helium (He) = 0.

Lithium (Li) = 1.

Beryllium (Be) = 2.

Boron (B) = 3.

Carbon (C) = 4.

Nitrogen (N) = 3.

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