Question

Good afternoon

My name is VANDITA YADAV and I am student of BYJUS 9th grade.

My doubt is related with chemistry : We have to learn the periodic table or just need to understand it.

In the first chapter of chemistry, the 2nd sub-chapter has table of cations where in the valency 4 - tetravalent elements, lead has the valency of 3+ instead of 4+. Is it an error or the lead has a valency of 3+ ? If yes then how?

Answer 1

Good after noon vandita,
I will explain what is balance electrone and what is valancy
Valency
The outermost electron shell of an atom is called valence shell.
The electrons present in outermost shell of an atom are called as valence electrons.
The valence electron of an atom take part in a chemical reaction because they have more energy than all the inner electrons.
For Ex:
1) Sodium(Z=11)
The electronic configuration of sodium is
K L M
2 8 1
Valence Electrons=1
2)Chlorine(Z=17)
The electronic configuration of chlorine is
K L M
2 8 7
Valence electrons=7
3)Magnesium(Z=12)
The electronic configuration of magnesium is
K L M
2 8 2
Valence Electrons=2
The combining capacity of an atom of an element to form chemical bond is called its valency.
The valency of an element is
1)Equal to the number of valence electrons
2)Equal to the number of electrons required to complete eight electrons in valence shell.
Valency of a metal=No. of Valence electrons
Valency Of a non-metal=8-No. of valence electrons
For Ex:
1)Sodium(Z=11)
Electronic Configuration=2,8,1
Valency=1
2)Magnesium(Z=2)
Electronic Configuration=2,8,2
Valency=2
3)Chlorine(Z=17)
Electronic Configuration=2,8,7
Valency=8-7=1
4)Oxygen=16
Electronic Configuration=2,8,6
Valency=8-6=2
There are some elements which do not combine with other elements.They are known as noble gases or inert gases.
For Ex:1)Helium(Z=2)
Electronic Configuration=2
Valency=2
2)Neon(Z=10)
Electronic Configuration=2,8
Valency=8
3)Argon(Z=18)
Electronic Configuration=2,8,8
Valency=8
4)Krypton(Z=36)
Electronic Configuration=2,8,18,8
Valency=8
All the noble gases have completely filled outermost shells.
1)Atoms having 8 electrons in their outermost shell are very stable and chemically unreactive.
2) Electrons in outermost shell is stable only when the atom has just one shell,k,shell.
The atoms combine with each other to achieve the inert gas electron arrangement and become more stable.
An atom can achieve the inert gas configuration by:
1)Losing one or more electrons(Valence electron=1,2,3)
2)Gaining one or more electrons(valence electron=5,6,7)
3)Sharing one or more electrons(Valence electrons=4)