Question

write down the symbols and atomic number of fixed 20 elements​

Answer 1

Hydrogen (H)        Atomic Number: 1  Valency = 1

Helium (He)          Atomic Number: 2  Valency = 0

Lithium(Le)           Atomic Number: 3  Valency = 1

Beryllium(Be)       Atomic Number: 4  Valency = 2

Boron(B)               Atomic Number: 5  Valency = 3

Carbon(C)            Atomic Number: 6  Valency = 4

Nitrogen(N)          Atomic Number: 7  Valency = 3  

Oxygen(O)              Atomic Number: 8  Valency = 2

Fluorine(F)           Atomic Number: 9  Valency = 1

Neon (Ne)               Atomic Number: 10 Valency = 0

Sodium(Na)            Atomic Number: 11 Valency = 1

Magnesium(Mg)                Atomic Number: 12 Valency = 2

Aluminium(Al)               Atomic Number: 13 Valency = 3

Silicon(Si)                 Atomic Number: 14 Valency = 4

Phosphorus(P)              Atomic Number: 15 Valency = 3  

Sulphur(S)                  Atomic Number: 16 Valency = 2

Chlorine(Cl)       Atomic Number: 17 Valency = 1

Argon(Ar)           Atomic Number: 18 Valency = 0

Answer 2

Answer:

Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Florin Neon Sodium Magnesium Aluminium Silicon Phosphorous Sulphur Chlorine Argon Potassium Calcium

Explanation:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20