Chemistry

Atoms and Molecules

Valencies of Some Common Metal Elements Valencies of Some Common Non-Metal Elements

Element	Symbol	Valency
Lithium Sodium Potassium Silver Copper Mercury Magnesium Calcium Zinc Iron Aluminium	Li Na K Ag Cu Hg Mg Ca Zn Fe Al	1 1 1 1 1 and 2 1 and 2 2 2 2 2 and 3 3

Element	Symbol	Valency
Hydrogen Fluorine Chlorine Bromine Iodine Oxygen Sulphur Nitrogen Phosphorus Carbon	H F Cl Br I O S N P C	1 1 1 1 1 2 2 3 3 4

Though the usual valency of sulphur is 2 as shown in the second table, it also shows valencies of 4 and 6 in some compounds. For example, the valency of S in

H

₂S is 2,in

SO

₂ is 4 and in SO3 is 6.Similarly,though the usual valency of nitrogen and phosphorus is 3, they also show a valency of 5 in some compounds.Please note that an element having a valency of 1 is called monovalent ; valency 2 elements are called divalent ; valency 3 elements are called trivalent ; valency 4 elements are called tetravalent ; valency 5 elements are called pentavalent whereas the valency 6 elements are called hexavalent. Dear student, we have given so many details here so that you are able to write the formulae of various compounds easily and correctly. We will now give the methods of writing the formulae of compounds.

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Notes

Atoms and Molecules - Notes

1. Drawbacks of Dalton’s Atomic Theory

2. Monovalent Cations (Cations Having a Valency of 1+)

3. Divalent Cations (Cations Having a Valency of 2+)

4. Dalton’s Symbols of Elements

5. Trivalent Cations (Cations Having a Valency of 3+)

6. Formulae of Some Molecular Compounds

7. An Important Discussion

8. Molecular Formulae of Some Common Elements

9. As an example, let us give the significance of the formula H₂O

10. an example, let us give the significance of symbol C

11. Molecules

12. 2. A Negatively Charged Ion is Known as Anion

13. Chemical Formulae

14. Molecules of Compounds

15. Explanation of the Law of Conservation of Mass

16. Molecular Mass

17. Atoms

18. Atoms, Molecules and Ions

19. Some Ionic Compounds

20. Mole of Molecules

21. John Dalton

22. Formulae of Elements

23. Gram Atomic Mass And Gram Molecular Mass

24. Formula Mass

25. 1. A Positively Charged Ion is Known as Cation

26. 1. Molecules of Elements

27. Simple Ions and Compound Ions (Polyatomic Ions)

28. Symbols of Elements

29. Mole of Atoms

30. Explanation of the Law of Constant Proportions

31. Formulae of Compounds

32. Dalton's Atomic Theory

33. Ions

34. Some Common Ions

35. Significance of the Formula of a Substance

36. Molecular Masses of Some Common Elements

37. Laws Of Chemical Combination

38. Ionic Compounds

39. How Do Atoms Exist

40. Calculation of Molecular Mass

41. Experiment to Verify Law of Conservation of Mass

42. Problems Based On Moles Of Molecules

43. Atoms And Molecules

44. Formula Unit of Ionic Compounds

45. Writing Of Formulae Of Ionic Compounds

46. Divalent Anions (Anions Having a Valency of 2-)

47. Gram Molecular Mass

48. Gram Atomic Mass

49. Atomic Mass Of An Element

50. Problems Based On Moles Of Atoms