Question

why copper has two valancies

Answer 1

Copper has two valencies 2 and 3 because of its electronic configuration the configuration is 2,8,18,1 in this case copper's valency is 1 because it needs to donate only 1 electron to become stable and in the other case configuration is 2,8,17,2 so copper donates 2 electrons to become stable and exhibiting the valency of 2 . Hope you like this answer

Answer 2

1) Hydrogen (H)

Atomic Number -- 1
Valency -- 1

2) Helium (He)

Atomic Number --2
Valency -- 0

3) Lithium (Le)

Atomic Number -- 3
Valency -- 1

4) Beryllium (Be)

Atomic Number -- 4
Valency -- 2

5) Boron (B)

Atomic Number-- 5
Valency -- 3

6)Carbon(C)
Atomic Number: 6
Valency = 4

7) Nitrogen (N)

Atomic Number --7
Valency -- 3

8) Oxygen (O)

Atomic Number --8
Valency --2

9) Fluorine (F)

Atomic Number -- 9
Valency --1

10) Neon (Ne)

Atomic Number -- 10
Valency -- 0

11)Sodium (Na)

Atomic Number --11
Valency -- 1

12) Magnesium (Mg)

Atomic Number -- 12
Valency -- 2

13) Aluminum (Al)

Atomic Number -- 13
Valency -- 3

14) Silicon (Si)

Atomic Number -- 14
Valency -- 4

15) Phosphorus (P)

Atomic Number -- 15
Valency -- 5 , 3

16) Sulfur (S)

Atomic Number -- 16
Valency -- 2

17) Chlorine (Cl)

Atomic Number -- 17
Valency -- 1

18) Argon (Ar)

Atomic Number -- 18
Valency -- 0

19) Potassium (K)

Atomic Number --19
Valency -- 1

20) Calcium (Ca)

Atomic Number -- 20
Valency -- 2

21) Scandium (Sc)

Atomic Number -- 21
Valency -- 3

22) Titanium (Ti)

Atomic Number --22
Valency -- 4

23) Vanadium (V)

Atomic Number --23
Valency -- 5 , 4

24) Chromium (Cr)

Atomic Number --24
Valency -- 2

25) Manganese (Mn)

Atomic Number -- 25
Valency -- 7 , 4 , 2

26) Iron (Fe)

Atomic Number -- 26
Valency -- 2 , 3

27) Cobalt (Co)

Atomic Number -- 27
Valency -- 3 , 2

28) Nickel (Ni)

Atomic Number -- 28
Valency -- 2

29) Copper (Cu)

Atomic Number -- 29
Valency -- 2 , 1

30 ) Zinc (Zn)

Atomic Number --30
Valency -- 2

Hope This Helps You!