In pentahalides, the oxidation state is +5 and in trihalides, the oxidation state is 3. Since the metal ion with a high charge has more polarizing power, pentahalides are more covalent than trihalides.
As we move down a group, the atomic size increases and the stability of the hydrides of group 15 elements decreases. Since the stability of hydrides decreases on moving from NH3 to BiH3, the reducing character of the hydrides increases on moving from NH3 to BiH3 .
The two N atoms in N2 are bonded to each other by very strong triple covalent bonds. The bond dissociation energy of this bond is very high. As a result, N2 is less reactive at room temperature.
Uses of neon gas: (i) It is mixed with helium to protect electrical equipments from high voltage. (ii) It is filled in discharge tubes with characteristic colours. (iii) It is used in beacon lights. Uses of Argon gas: (i) Argon along with nitrogen is used in gas-filled electric lamps. This is because Ar is more inert than N. (ii) It is usually used to provide an inert temperature in a high metallurgical process. (iii) It is also used in laboratories to handle air-sensitive substances.
NH3 acts as a Lewis base. It donates its electron pair and forms a linkage with metal ion. Cu 2+ + 4 NH3 ↔ [Cu(NH3 ) 4]2+
White phosphorous dissolves in boiling NaOH solution (in a CO2 atmosphere) to give phosphine, PH3 . P4 + 3NaOH + 3 H2 O ? PH3 + 3 NaH2 PO2
All the bonds that are present in PCl5 are not similar. It has three equatorial and two axial bonds. The equatorial bonds are stronger than the axial ones. Therefore, when PCl5 is heated strongly, it decomposes to form PCl3 . PCl5 → PCl3 + Cl2
PCl5 + D2 O → POCl3 + 2DCl2 POCl3 + 3D2 O → D3 PO4 + 3DCl Therefore, the net reaction can be written as PCl5 + 4 D2 O → D3 PO4 + 5DCl
H3 PO3 , on heating, undergoes disproportionation reaction to form PH3 and H3 PO4 . The oxidation numbers of P in H3 PO3 , PH3 , and H3 PO4 are 3, ?3, and 5 respectively. As the oxidation number of the same element is decreasing and increasing during a particular reaction, the reaction is a disproportionation reaction. 4H3 PO3 → 3H3 PO4 + PH3
Sulphur mainly exists in combined form in the earth crust primarily as sulphates [gypsum (CaSO4 .2H2 O), Epsom salt (MgSO4 .7H2 O), baryte (BaSO4 )] and sulphides [galena (PbS), zinc blends (ZnS), copper pyrites (CuFeS4 )].
H2 O has oxygen as the central atom. Oxygen has smaller size and higher electronegativity as compared to sulphur. Therefore, there is extensive hydrogen bonding in H2 O, which is absent in H2 S. Molecules of H2 S are held together only by weak Van der Waals forces of attraction. Hence, H2 O exists as a liquid while H2 S as a solid.
Pt is a noble metal and does not react very easily. All other elements, Zn, Ti, Fe, are quite reactive. Hence, oxygen does not react with platinum (Pt) directly.
(i) C2 H4 + O2 → 2CO2 + 2 H2 O (ii) 4Al + 3O2 → 2Al2 O3
Ozone is not a very stable compound under normal conditions and decomposes readily on heating to give a molecule of oxygen and nascent oxygen. Nascent oxygen, being a free radical, is very reactive. O3 → O2 + [O] Therefore, ozone acts as a powerful oxidising agent.
Noble gases do not form molecules. In case of noble gases, the atomic radii corresponds to Van der Waals radii. On the other hand, the atomic radii of other elements correspond to their covalent radii. By definition, Van der Waals radii are larger than covalent radii. It is for this reason that noble gases are very large in size as compared to other atoms belonging to the same period.