Question

Define the following terms: (a) electron-deficient (b) electron - precise (c) electron-rich compound. Justify your answer with an example?

Answer 1

Electron deficient:

• Electron-deficient compounds are those compounds that don't have a sufficient number of electrons to complete the octet of the central atom.
• These compounds contain insufficient numbers of electrons to form normal electron-pair bonds between each pair of bonded atoms.
• Electron deficient compounds exist in polymorphic forms to complete their electron deficiency.
• Example: The compounds containing less than 8 electrons in the valence shells are called electron-deficient compounds such as B₂H₆, AlH₃, etc.

Electron precise :

• Electron precise compounds of hydrogen contain sufficient valence electrons to form covalent bonds.
• The type of hydrides that have the exact number of electrons to form a covalent bond is called electron precise.
• These types of compounds are usually formed by group 14 elements.
• The compounds usually have a tetrahedral shape.

Example: CH₄, SiH₄, etc.

Electron rich:

• The type of hydrides that have more electrons than required for bonding is called electron-rich hydrides.
• The excess number of electrons is mainly the lone pair of electrons on the central atom.
• These types of compounds are usually formed by groups of 15, 16, and 17 elements.
• Example: NH₃, PH₃, etc.

Example: NH₃, PH₃, etc.