2. Chemical Bonding
Electrovalent, covalent and co-ordinate bonding, structures of various compounds, Electron dot structure.
(a) Electrovalent bonding:
- Electron dot structure of Electrovalent compounds NaCl, MgCl₂, CaO.
- Characteristic properties of electrovalent compounds – state of existence, melting and boiling points, conductivity (heat and electricity), dissociation in solution and in molten state to be linked with electrolysis.
(b) Covalent Bonding:
- Electron dot structure of covalent molecules on the basis of duplet and octet of electrons.
- Non-polar covalent compounds (example: hydrogen, chlorine, oxygen, nitrogen, carbon tetrachloride, methane.)
- Polar Covalent compounds – based on difference in electronegativity: Examples – HCl, NH₃ and H₂O including structures.
- Characteristic properties of Covalent compounds – state of existence, melting and boiling points, conductivity (heat and electricity), ionisation in solution. Comparison of Electrovalent and Covalent compounds.
(c) Coordinate Bonding:
- Definition.
- The lone pair effect of the oxygen atom of the water molecule and the nitrogen atom of the ammonia molecule to explain the formation of H₃O⁺ and OH⁻ ions in water and NH₄⁺ ion. The meaning of lone pair; the formation of hydronium ion and ammonium ion must be explained with the help of electron dot diagrams.