D,J,Z,E and L are 15th group elements belonging to Modern periodic table. The correct trend of electron donating power of hydrides is DH3 > JH3 > ZH3 > EH3 > LH3. The element ‘J’ in the sequence is
Down the group as the size of the atom increases affinity of hydrogen towards central atom decreases. Therefore
a) X-H bond enthalpy decreases….N-H>P-H>As-H>Sb-H>Bi-H ;
b) Thermal stability decreases….NH3>PH3>AsH3>SbH3>BiH3 ;
NH3 is exothermic product,remaining four hydrides are endothermic products.
c) Reducing power increases….NH3<PH3<AsH3<SbH3<BiH3 ;
d) Acidic strength (Ka) increases….NH3<PH3<AsH3<SbH3<BiH3 ;
e) pKa decreases……NH3>PH3>AsH3>SbH3>BiH3 ;
Down the group as vanderwaal's forces increases
Melting and boiling points increases
Expected BP and MP….NH3<PH3<AsH3<SbH3<BiH3
Due to H-bonding in NH3, it has higher BP and MP than expected.
BP trend…...PH3<AsH3<.NH3<SbH3<BiH3
MP trend…..PH3<AsH3<.SbH3<BiH3<NH3
Central atom in these hydrides contain one lone pair, according to Bent rules
As the Electronegativity of central atom decreases,
Bond angle decreases….NH3>PH3>AsH3>SbH3>BiH3 ;
Down the group as the size of central atom increases, electron density on central atom decreases. Thus
a) Basicity decreases,Lewis base strength decreases…..NH3>PH3>AsH3>SbH3>BiH3 ;
b) Electron donating power decreases……NH3>PH3>AsH3>SbH3>BiH3 ;
c) Ligand strength and ability to form dative bond decreases….NH3>PH3>AsH3>SbH3>BiH3 ;