Covalent or molecular Hydrides are non-stoichiometric. True or False?
Covalent or molecular Hydrides are non-stoichiometric. True or False?
The correct option is B False
The hydrides of most of the P block elements are covalent - for instance NH3, CH4 and H2O. Being covalent, these compounds tend to be more volatile than ionic hydrides. Molecular hydrides are further classified according to the relative numbers of electrons and bonds in their Lewis structure into:
1.electron-deficient
2.electron-precise
3.electron-rich hydrides
An electron-deficient hydride: In hydrides of group 13 elements, the central atom usually has an incomplete octet . These are electron deficient and exist in polymeric forms as in (AlH3)n. In these structures, Hydrogen atoms seem to be bonded to two or more atoms via multi-centre bonding. Diborane (B2H6), the simplest boron hydride is a lewis acid (electron pair acceptor).
Electron precise - group 14 CH4
Al4C3+12HCl→3CH4+4AlCl3
In methane, all the atoms have stable, noble-gas electronic configurations. All the electrons are involved in bonding.
Electron-rich hydrides
1.These covalent hydrides have excess electrons in the form of lone pairs. Elements of group 15-17 form such compounds. (NH3 has 1- lone pair, H2O - 2 and HF -3 lone pairs).
2.They would behave as lewis bases (electron pair donor).
Note: as we move from Boron to Flourine in the same period, the tendency of the hydrides has an interesting pattern. Hydrides of Boron are electron deficient. Methane is electron precise while moving further away reveals a progressively electron-rich trend. As we can see, these compounds have a definite stoichiometric ratio between the binary elements. They have a definite ratio
False
The hydrides of most of the P block elements are covalent - for instance NH3, CH4 and H2O. Being covalent, these compounds tend to be more volatile than ionic hydrides. Molecular hydrides are further classified according to the relative numbers of electrons and bonds in their Lewis structure into:
1.electron-deficient
2.electron-precise
3.electron-rich hydrides
An electron-deficient hydride: In hydrides of group 13 elements, the central atom usually has an incomplete octet . These are electron deficient and exist in polymeric forms as in (AlH3)n. In these structures, Hydrogen atoms seem to be bonded to two or more atoms via multi-centre bonding. Diborane (B2H6), the simplest boron hydride is a lewis acid (electron pair acceptor).
Electron precise - group 14 CH4
Al4C3+12HCl→3CH4+4AlCl3
In methane, all the atoms have stable, noble-gas electronic configurations. All the electrons are involved in bonding.
Electron-rich hydrides
1.These covalent hydrides have excess electrons in the form of lone pairs. Elements of group 15-17 form such compounds. (NH3 has 1- lone pair, H2O - 2 and HF -3 lone pairs).
2.They would behave as lewis bases (electron pair donor).
Note: as we move from Boron to Flourine in the same period, the tendency of the hydrides has an interesting pattern. Hydrides of Boron are electron deficient. Methane is electron precise while moving further away reveals a progressively electron-rich trend. As we can see, these compounds have a definite stoichiometric ratio between the binary elements. They have a definite ratio
