CLASS 10 CHEMICAL BONDING ICSE NOTES
· Chemical bonding: The force by which two (or more) atoms are held together to form a stable molecule.
ü
Why
do atoms participate in chemical bonding ?
Reason:
The elements with unstable electronic configuration participate in chemical
bonding to attain stable electronic configuration.
ü How
do the atoms form chemical bonds and attain stable electronic configuration?
Ans: The atoms having unstable
electronic configuration lose or gain electrons or share electrons with other
atoms to attain stability.
ü What
is stable electronic configuration?
If an element has 8 electrons in
its valence shell (outer most orbit) or completely filled valence shell then it
is said to have stable electronic configuration.
e.g : Noble gases posses stable
electronic configuration.
Noble gas
|
Electronic configuration
K L M
N
|
Helium
|
2
|
Neon
|
2 8
|
Argon
|
2 8
8
|
Krypton
|
2 8
18 8
|
v Since
the noble gases have stable electronic configuration they do not participate in
chemical bonding hence they are inert.
v Helium
has duplet configuration i.e. 2 electrons in valence shell
v Noble
gases other than Helium have octet configuration i.e. 8 valence electrons.
·
“The
elements with unstable electronic configuration tend to attain the stable electronic configuration of
the nearest noble gas by either electron transfer or sharing electrons”- Octet
rule
Stable
electronic configuration (stability) is attained by an in the following ways:
i)
By electron transfer between two atoms- Electrovalent bond
ii)
By the mutual sharing of electrons
between the atoms- Covalent bond
Electrovalent
bond (or) Ionic bond: The transfer of electron/s
between the atoms with a higher difference in their electronegativity values
leads to the formation of Electrovalent bond.
Covalent
bond : The mutual sharing of electrons between the atoms whose
electronegativity difference is negligible results in a Covalent bond.
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