Covalent Bonds vs. Ionic Bonds
There are two types of atomic bonds - ionic bonds and covalent bonds. They differ in their
structure and properties. Covalent bonds consist of pairs of electrons shared by two atoms, and
bind the atoms in a fixed orientation. Relatively high energies are required to break them (50 200 kcal/mol). Whether two atoms can form a covalent bond depends upon their
electronegativity i.e. the power of an atom in a molecule to attract electrons to itself. If two
atoms differ considerably in their electronegativity - as sodium and chloride do - then one of
the atoms will lose its electron to the other atom. This results in a positively charged ion (cation)
and negatively charged ion (anion). The bond between these two ions is called an ionic bond.
Comparison chart
Covalent Bonds
Ionic Bonds
Polarity
Low
High
Formation
A covalent bond is formed between two
non-metals that have similar
electronegativities. Neither atom is
"strong" enough to attract electrons from
the other. For stabilization, they share their
electrons from outer molecular orbit with
others.
An ionic bond is formed between a
metal and a non-metal. Non-metals(ve ion) are "stronger" than the
metal(+ve ion) and can get electrons
very easily from the metal. These two
opposite ions attract each other and
form the ionic bond.
Shape
Definite shape
No definite shape
What is it?
Ionic bond, also known as
electrovalent bond is a type of bond
Covalent bonding is a form of chemical
formed from the electrostatic
bonding between two non metallic
attraction between oppositely
atoms which is characterized by the
charged ions in a chemical
sharing of pairs of electrons between
compound. These kinds of bonds
atoms and other covalent bonds.
occur mainly between a metallic and
a non metallic atom.
Melting point
low
High
Examples
Methane (CH4), Hydro Chloric acid (HCl)
Sodium chloride (NaCl), Sulphuric
Acid (H2SO4 )
Occurs
between
Two non-metals
One metal and one non-metal
Boiling point
Low
High
State at room
temperature
Liquid or gaseous
Solid
Metallic bonding
The particles in a metal are held together by metallic bonds.
High melting and boiling points- Metallic bonds are strong and a lot of energy is needed to
break them. This is why metals have high melting points and boiling points.
Conducting electricity- Metals contain electrons that are free to move in the metal structure,
carrying charge from place to place and allowing metals to conduct electricity well.
Metallic bonding is the strong attraction between closely packed positive metal ions and a
'sea' of delocalized electrons.
The attraction between the metal ions and the delocalised electrons must be overcome to
melt or to boil a metal. Some of the attractions must be overcome to melt a metal and all of
them must be overcome to boil it. These attractive forces are strong, so metals have high
melting and boiling points.
The delocalized electrons are able to move through the metal structure. When a potential
difference is applied, they will move together, allowing an electric current to flow through the
metal.