Tag: properties of covalent compounds

In the above question element A is equivalent to chlorine& B to sodium thus the structure besides shows the bonding giving rise to $NaCl$ Hence for our eg, it is $BA$.

Ionic compounds are soluble in water whereas covalent compounds are insoluble in water.

Covalent bonds between atoms are quite strong, but attractions between molecule/compounds  or intermolecular forces, can be relatively weak. Covalent compounds generally have low boiling and melting points, and are found in all three physical states covalent bonds between atoms are quite strong, but attractions between molecules/compounds or intermolecular forces, can be relatively work. Covalent compounds generally have low boiling and melting points, and are found in all three physical states at room temperature. at room temperature.

A and B differ wrt type of hybridization of central atom. 'B' may have lone pair on central atom whereas 'A' has no lone pair.
'A' has dipole moment as it is trigonal planar in which individual bond dipoles cancel each other and dipole moment of 'B' is zero as it has pyramidal geometry in which individual bond dipoles do not cancel each other. 

Compound in statement 1 must be $C{ H } _{ 3 }Cl$.Since carbon,hydrogen and chlorine have different electronegativity,the bonds are polar in nature. Moreover, there is symmetry in the structure of the molecule, so there is a net dipole moment hence it is a polar molecule.

Covalent bonds are directional and ionic bonds are nondirectional. A polar bond is formed between two atoms which have different electronegativity value. The presence of polar bonds in a polyatomic molecule suggests that mostly it has non-zero dipole moment.