What do you understand by (i) electron rich (ii) electron-precise, and (iii) electron-deficient? – compounds of hydrogen, Provide justification with suitable examples.
(i) Electron deficient compounds of hydrogen do not have sufficient number of electrons to form normal covalent bonds. Examples include hydrides of group 13 such as BH3,AlH3 etc. They exist in polymeric forms such as B2H6,Al2H6. Thus, they make up their deficiency. (ii) Electron precise compounds of hydrogen contain sufficient valence electrons to form covalent bonds. Examples include group 14 hydrides CH4,SiH4,GeH4,SnH4,PbH4 etc. These compounds have tetrahedral shape. (iii) Electron rich compounds of hydrogen contain excess valence electrons to form covalent bonds. Examples include group 15 and group 17 hydrides such as NH3,PH3,HCl,HBr etc. These compounds contains lone pairs of electrons.
