ICSE CHEMISTRY - Chemical bonding

ICSE CHEMISTRY - Chemical bonding

   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.