Question

what is the valency of 1 to 20 element

Answer 1

The first 20 elements in the periodic table start with H and end with Ca. As acc. to the periodic table the valencies are 
1 Hydrogen 1 
2 Helium 0 
3 Lithium 1 
4 Beryllium 2 
5 Boron 3 
6 Carbon 2, 4 
7 Nitrogen 3, 5 
8 Oxygen 2 
9 Fluorine 1 
10 Neon 0 
11 Sodium 1 
12 Magnesium 2 
13 Aluminium 3 
14 Silicon 4 
15 Phosphorus 3, 5 
16 Sulphur 2, 4, 6 
17 Chlorine 1, 3, 5, 7 
18 Argon 0 
19 Potassium 1 
20 Calcium 2