Question

List of first 20 elements with atomic mass,symbol,atomic number,valency

Answer 1

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Answer 2

The first 20 elements of the periodic table with their atomic mass, symbol, atomic number and valence are given below:

Atomic no. - Element - Symbol - A. Mass- Valency

1 - Hydrogen- H- 1 - 1

2 - Helium - He- 4 - 0

3 - Lithium - Li- 7 - 1

4 - Beryllium - Be- 9 - 2

5 - Boron - B- 11 - 3

6 - Carbon - C- 12 - 4

7 - Nitrogen - N- 14 - 3

8 - Oxygen - O- 16 - 2

9 - Fluorine - F- 19 - 1

10 - Neon - Ne- 20 - 0

11 - Sodium - Na- 23 - 1

12 - Magnesium - Mg- 24 - 2

13 - Aluminium - Al- 27 - 3

14 - Silicon - Si- 28 - 4

15 - Phosphorus - P- 31 - 3

16 - Sulphur - S- 32 - 2

17 - Chlorine - Cl- 35.5 - 1

18 - Argon - Ar- 40 - 0

19 - Potassium - K- 39 - 1

20 - Calcium - Ca- 40 - 2

( A.Mass is the atomic mass of the element. The valency of an element is defined as the number of electrons in the outermost shell till 4 and if the electrons are more than 4 then the valency will be the subtraction of the electrons from 8.)