(i) Periodic properties and their variations in groups and periods. Definitions of the following periodic properties and trends in these properties in groups and periods should be studied: Atomic size Metallic character Non-metallic character Ionisation potential Electron affinity Electronegativity (ii) Periodicity on the basis of atomic number for elements. The study of modern periodic table up to period 4 (students to be exposed to the complete modern periodic table but no questions will be asked on elements beyond period 4 – Calcium); Periodicity and other related properties to be explained on the basis of nuclear charge and shells (not orbitals).

(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 (example: hydrogen, chlorine, nitrogen, ammonia, 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 help of electron dot diagrams