Atomic Bonding Test - 4

The covalency of 'N' in NH₄⁺ ion is equal to number of covalent and co-ordinate bonds.

The electon configuration of boron is 1s², 2s², 2p¹ and three electron in its valence shell. Thus due to three electrons in its valence shells of the central atom it form BF₃ molecule.

Electrolyte is a solution and a medium that consists of free ions which help in the conduction of electricity. Ammonia in water is an example for weak electrolyte. It exists as molecule in water and to some extent get dissociated as ion. Since the weak electrolytes have fewer ions in the solution, it acts as weak conductor of electricity.

Ionic bond is formed when atoms of an element (usually metal), whose ionization energy is low, release some of their electrons to achieve a stable electron configuration. In doing so, cations are formed. The atom of another element (usually non-metal), whose electron affinity is positive, then accepts the electron(s), again to attain a stable electron configuration, and after accepting electron(s) the atom becomes an anion.

MgH₂ is an ionic hydride because hydride formed by alkali metals are known as ionic hydride.

Metals can form ionic hydride by the lose of electrons. But CH₄ is a covalent molecule as it is formed by only sharing of electrons.

Covalent bonds are formed by sharing of electrons. They do not have a free electron that is required for electricity transfer (electricity is the flow of free electrons. Thus, they are bad conductors of electricity, e.g. CH₄ and Cl₂.

Whereas, ionic compounds are good conductors of electricity only in molten state and in their aqueous solutions. This is because in molten state/aqueous solution, the free ions move around freely and conduct electricity, e.g. MgCl₂(aq).

Moreover, NaCl(s) is an ionic compound but is a bad conductor because it is in its solid state as the ions are not free to move.

Polar compound is a compound in which the electric charge is not symmetrically distributed, so that there is a separation of charge or partial charge and formation of definite positive and negative poles, H₂O and HCl.

In FeCl₃, Fe exist in +3 state as Fe³⁺ cation while in FeCl₂, Fe exist in +2 state as Fe²⁺ cation. As we know greater the charge greater will be the covalent nature. Thus, in Fe³⁺ cation, due to the greater charge greater will be the polarizibility and so it has more covalent character. Hence, FeCl₃ has more covalent character than in FeCl₂.