1. What are the different types of bonds in solids? (or)
Explain various types of bonding in solids with suitable examples.
Ans: Broadly there are two types of bonds.
1. Primary bonds also known as interatomic bonds
2. Secondary bonds also known as inter molecular bonds
Primary bonds are strong bonds which hold the atoms together. There are three types of primary bonds:
Ionic bonds, covalent bonds and metallic bonds. Secondary bonds are weaker than primary bonds. Examples
for secondary bonds are hydrogen bonds and vanderwaal bonds.

Bonds which are localized and occur in fixed angles with respect to each other are directional bonds.
Covalent and hydrogen bonds are directional bonds.
In non – directional bonds, bonding is equal at all angles. The bond is not localized to specific
direction. Ionic, metallic and vanderwaals bonds are non directional.
Ionic Bonds:
By transferring elections from one atom to another, electron shells are filled. The donor
atom will take a positive charge and the acceptor will have a negative charge. The charged atoms or ionic
will be attracted to each other and form bonds. NaCl is the most common example. When sodium and
chlorine atoms are placed together, there is a transfer of electrons from the sodium to the chlorine atoms,
resulting in a strong electronics attraction between the positive sodium ions and the negative chlorine ions.
Ions crystals are usually insulators transparent, soluble in polar solvents like water and insoluble in non
polar solvents like benzene.

Covalent Bonds
:
 covalent bond is also called
some atoms share the electrons in their outermost shell.
Example: Diamond, O-O, H2 etc. Covalent bonds are very strong directional bonds. Crystal with covalent
bonds are hard and brittle and do not conduct electricity because of non availability of free electrons. A
single covalent bond occurs in the hydrogen molecule.
Binding energy is high so that their melting point and boiling points
are high. Covalent substance are insoluble in water.
Metallic Bonds: In metallic bonds the outermost electrons of
metals are shared among all the atoms in the solid. Each atom gives
up its outer electrons and becomes slightly positively charges. The valence electrons form a negative
electron cloud. These electrons are not associated with a particular ion but are free to move within the
surface of the metal.
Metals are opaque , ductile, malleable. These have low melting
points, high density and have good thermal and have good thermal
and electrical conductivity.
Vanderwaals Bonds: Mutual polarization of atoms due to each
other takes place.
Hydrogen Bond:The electrostatic force of attraction between a
partially positively charged hydrogen atom of a polar molecule and a highly electron negative atom is
known as hydrogen bond. In Hydrogen bond lowering of kinetic energy of proton by the arrangement O-HO
takes place.