Question

Mass no and valency of first 20elements

Answer 1

Atomic number Element Atomic mass Valency Protons Neutrons 1Hydrogen 1 1 1 0
2Helium 4 0 2 2
3Lithium 7 1 3 4
4Beryllium 9 2 4 5
5Boron 11 3 5 6
6Carbon 12 4 6 6
7Nitrogen. 14 3 7 7
8Oxygen. 16 2 8 8
9Fluorine 19 1 9 10
10Neon 20 0 10 10
11Sodium 23 1 11 12
12Magnesium. 24 2 12 12
13Aluminium 27 3 13 14
14Silicon. 28 4 14 14
15Phosphorous 31 5,3 15 16
16Sulphur 32 2 16 16
17Chlorine 35 1 17 18
18Argon 40 0 18 22
19Potassium 39 1 19 20
20Calcium 40 2 20 20

Answer 2

element. valency.
hydrogen. 1
helium 0
lithium. 1
beryllium 2
boron 3
carbon 4
nitrogen. 3
oxygen. 2
fluorine. 1
neon. 0
sodium. 1
magnesium. 2
aluminum 3
silicon. 4.