P-Block elements give reasons Flashcards
There is a considerable increase in covalent radius from N to P, but a small difference from As to Bi
Presence of completely filled D and / F orbitals in heavier members
Ionization enthalpy of group 15 is more than that of group 16
Presence of half filled p orbitals in group 15 elements, making it extra stable
In group 15, stability of +5 decreases and that of +3 increases down the group
Inert pair effect
Nitrogen exhibits +1, +2, +4, +5 oxidation state, but does not form compounds of +5 oxidation state with halogens
It does not have d orbital to accommodate other electrons to form a bond
N is restricted to a maximum covalency of 4
only four orbitals are available for bonding (one s and three p)
Heavier group 15 elements dont form p Pi - p Pi bond
atomic orbitals are so large and diffuse that they cannot have effective overlapping
Single N-N bond is weaker that single bond of other group 15 elements
High interelectronic repulsion of non bonded electrons, since N-N bond length is small
NH3 has higher boiling & melting points that PH3
NH3 exhibits hydrogen bonding in solids as well as liquids
Pentahalides are more covalent that trihalides
In pentahalides, +5 oxidation state exists while in trihalides +3 exists. Since elements in +5 oxidation state will have more polarizing power than +3, Covalent character of bonds is more in pentahalides.
Dinitrogen is quite inert at room temperature
high bond enthalpy of NN triple bond
NH3 has a small molecular mass, but has high boiling and melting points
It is associated through hydrogen bonds in the solid and liquid state.
Ammonia aqueous solution is weakly basic
Formation of OH- ions
NH3 acts as a lewis base
There is a lone pair of electrons on the Nitrogen atom
Group 16 elements have lower ionization enthalpy as compared to Group 15
Group 15 has half filled P orbitals, giving it extra stability
Oxygen has less negative electron gain enthalpy than Sulphur
Compact nature of O
There is a large difference in melting and boiling points of O and S
Oxygen exists as a diatomic molecule, (O2), Sulphur exists as a polyatomic molecule (S8).
Oxygen displays oxidation states of 2, and rarely , 4. But other group 16 elements show variations
Oxygen shows absence of d orbital
Combination of O with other is highly exothermic. To initiate the reaction, heating is required
Because O-O bond enthalpy is high
During preparation of Ozonized oxygen , a silent electrical discharge is required.
Since the process is endothermic, silent electrical discharge is required to prevent its decomposition.
Ozone is thermodynamically unstable as compared to oxygen
Its decomposition into oxygen results in the liberation of heat, (H= -ve) and increase in entropy (S= +ve )
since G = H - TS, Gibbs free energy is -ve.
Nitrogen oxides are threatening to the ozone layer
particularly nitrogen monoxide, NO, combines rapidly with ozone , O3 , there is a possibility that nitrogen oxides emitted from aircrafts are depleting the concentration of the ozone layer
Care should be taken while diluting concentrated diluted Sulphuric acid
Sulphuric acid dissolving in water is a highly exothermic reaction.
Wet gases are passed through suphuric acid
Sulphuric acid is a good dehydrating agent
Sulphuric acid seems to char carbohydrates
H2SO4 removes water from organic compounds
