Metallic & non metallic oxides nature
As the effective nuclear charge increases, the atomic radii decreases in a period & electronegativity increases. The ionization enthalpy & negative electron gain enthalpy also increase. This shows that the tendency to gain electrons is increasing that is non metallic character increases & metallic character decreases from left to right in a period.
On the other hand, moving down the group the shielding effect increases. Thus reducing the nuclear force of attraction on electrons , consequently the atomic radius increases. The electronegativity decreases, the ionization enthalpy & negative electron gain enthalpy value decreases. This shows that the tendency to donate electron increases that is metallic character character increases and non metallic character decreases.
Generally metallic oxides are basic in nature & non metallic oxides are acidic in nature. The element in higher oxidation state forms acidic oxide & in lower oxidation state forms basic oxides.
Al2O3 – Amphoteric Oxides
CO,NO,N2O – Neutral oxides
Diagonal Relationship:
On observation it had been found that the elements of second period have a striking similarity with the elements of the third period placed diagonally to each other, belonging to different groups. The behavior of lithium & berrylium is more similar to magnesium & aluminium respectively. This similarity in properties of elements placed diagonally to each other is called diagonal relationship in periodic properties.
Li shows similar properties with Mg
Be shows similar properties with Al
B shows similar properties with Si