Question

Define atomic number , mass number and valency(explain with example in hindi )

Answer 1

atomic number > number of protons present in atom represent atomic number
ex C6, Na11

mass number > the sum of proton and neutron of an atom is called mass number
ex, Na^11+12

valency > the combining capacity of an atom is called valency
ex, carbon has 4 valency

Answer 2

What is valency ?

=> Valency is the combining capacity of an atom with another atom (s) .

This is normally given by the number of Valence electrons or by 8 minus the Valence electrons (Only when the number of Valence electrons is more than 4) .

Valency of first 20 elements is given below.
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

#Be Brainly !!