Step-by-step explanation:
Here, we want to discuss ionic and covalent compounds
Ionic compounds also called electrovalent compounds are compounds that are formed when electrons are transferred from the valence shell of an electropositive atom (usually a metal) to the valence shell of an electronegative atom (usually a non-metal or a less electropositive or more electronegative atom), which results in bonding.
Take for example the case of Sodium and chlorine
Sodium has three shells with shell configuration 2,8,1 with one electron in its valent shell
Removing the extra 1 electron in its last shell will make it achieve the stability of a noble gas which is one of the reasons we do not have some elements existing in uncombined forms. It needs an atom to accept this extra electron it wants to remove
Now, here comes chlorine with shell configuration 2, 8, 7
It needs an extra electron to achieve the noble gas configuration
Hence, it will gladly accept the elcctron sodium wants to donate
This type of bonding that react from the transfer of the electron is the ionic bond. The electron is completely transferred to the chlorine shell and has no interaction anymore with the sodium atom
Example of this compound is Sodium Chloride
Molecular compounds are formed from electron sharing. The key word here is sharing as different from the transfer keyword in ionic compouunds. Since the electron is shared, it is controlled by both atom since it is still within their valence shells
A practical application can be seen in the case of carbon (iv) oxide
Here, we have a central carbon atom and two side oxygen atoms
The carbon atom has the shell configuration of 2,4 (it needs 4 extra electrons to achieve stability).
For the oxygen , the configuration is 2,6 (they both need 2 each since they are 2)
So, there must be an interaction.
Hence, we can have the 4 from the carbon shared 2 ,2 . But it will be within the two shells.
The carbon has 8 now ( 4 itself and 2 each from the contributing oxygen)
For the oxygen, they have 8 too (6 itself and 4 distributed 2, 2 for each oxygen)
This type of covalent bonding is the ordinary covalent bonding.
An example of this compound is carbon (iv) oxide
Covalent bonding occurs between atoms of similar electronegativity such as between non metals.
The difference between the two is that in ionic bonding, there is transfer of electrons while in covalent bonding, there is sharing of electrons