Question

(i) State the limitations of J.J. Thomson‟s model of an atom. (ii) Define valency by taking the examples of magnesium (At. no8) and oxygen (At. no8) (iii) S2 has completely filled K,L and M shells. Find its atomic number.

Answer 1

according to jj Thomson model atomicstructure is just like water melon .red part is positive and seeds are negative. but in this model we don't understand the concept of nucleus, configuration of atom spectrum phenomena etc.
mg atm no 24 a/c theory 1s2 2s2 2p6 3s2 3p6 4s2 3d4 so valency is 6
o atm no 8 1s2 2s2 2p4 here valency is 2

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 !!