Sodium Chloride (NaCl) commonly termed as common salt, is a metal halide that is composed of sodium and chloride.
Both sodium and chloride possess the capability of being replaced. As a result of which, in times of need and emergencies the Sodium can be replaced to maintain the intracellular osmolarity.
It is also beneficial for the conduction of nerves, contraction of muscles as well as maintaining the proper renal function.
There is an abundance of the mineral Sodium Chloride on Earth and is an essential requirement for both plants as well as animals.
The inorganic chloride salt i.e. Sodium Chloride comprises Sodium (+1) which acts as the counterion. The crystalline white solid acts as a flame retardant.
So, is Sodium Chloride (NaCl) is ionic or covalent? Sodium Chloride is an Ionic compound, it is formed by the transfer of electrons among its atoms that results in the formation of ions. Sodium being an alkali metal forms a monovalent ion by donating its one valence electron and forms a (+1) charge. While on the other hand Chlorine, being a halogen forms a monovalent ion by accepting an electron. Therefore, Sodium forms Na (+1) charge, Chlorine on the other hand form Cl (-1).
The ions formed exert electrostatic force upon each other. This leads to the formation of Ionic bonds. The Ionic bonds are formed between a metal and a nonmetal.
What is an Ionic Bond?
An Ionic Bond takes place in between two or more atoms, where there is the transfer of one or more than one electron across the atoms.
The transfer of electrons between the atoms results in the formation of positive ions which are known as the cations and also results in the formation of negative ions which are known as the anions.
These anions and cations attract each other and form the Ionic bond between the atoms.
The complete transfer of some electrons in between two atoms or more results in the formation of the Ionic bond.
An electrostatic force is initiated between the negatively charged anions and the positively charged cations.
During the process of electron transfer, this electrostatic attraction taking place between the two oppositely charged atoms concludes the formation of the Ionic bond.
Na (+1) and Cl (-1) form an Ionic bond by exchanging electrons. Generally, the electron orbitals don’t overlap with each other. The main reason being, each of the ions reaches its lowest level of state of energy.
The bond generally is only based on the electrostatic attraction between the positively charged cations and the negatively charged anions. Several examples have been found where the ionic solids are soluble in water.
Although complete solubility doesn’t take place. The solubility of the ionic solids in the water will take place depending on the degree of attraction.
The cations are attracted to the ion pairs on water molecules while at the same time coordinate bonds are also formed.
Difference between Ionic and Covalent Bond
In the Ionic bond, the metallic atom loses the electron while the nonmetallic atom gains the electrons. Such bonds are comparatively stronger than Hydrogen bonds.
As opposed to covalent bonds where atoms are bonded together by the process of sharing electrons, in Ionic bonds the atoms are bonded by the exchange of two oppositely charged ions.
The geometry of each atom is determined by the Valence Shell Electron Pair Repulsion Theory (VSEPR Theory) in the Covalent Bond.
While in the ionic bond the geometry of each atom is determined by the maximum packing rules. The geometry of the atoms helps in the classification of whether the compound is an ionic or covalent compound.
The overall change of energy plays a vital role in determining the bond. The larger the change of energy the stronger is the bond formation.
Therefore, with a larger difference in electronegativity, the bond is going to be more Ionic between the two or more atoms.
Why does NaCl form an Ionic Bond?
It is important to understand the ionic bond of NaCl. The Sodium atom comprises 11 protons as well as 11 electrons. It has only one single valence electron in the 3s subshell.
Before understanding the electron configuration, we will like to introduce the concept of s and p orbitals.
S orbital is the symmetrical orbit that is spherical in shape and is present around the nucleus of an atom. With the gradual increase in energy, the electrons are pushed farther and therefore get located farther from the nucleus. As a result of which the orbitals get enlarged.
On the other hand, there is a concept of p orbitals. At the first level of energy, the orbital is available for the electrons in the 1s orbital.
As the energy increases, the electrons also have the availability of the 2s orbitals and the 2p orbitals. Unlike s orbitals, the p orbitals are positioned in a particular direction.
At any particularly given energy level, there is a presence of three equivalent p orbitals that points mutually at right angles to each other.
The Chlorine atom comprises 17 protons and 17 electrons respectively. In the third shell, there exist seven valence electrons which are represented by 3s2 3p5.
The metal and the non-metal form an ionic bond by the process of donating and accepting electrons.
The Sodium atom being an electropositive atom loses its single valence electron which will be accepted by Chlorine. The resultant, electronic configuration of the Sodium ion is 1s2 2s2 2p6.
Therefore, the sodium ion gains a charge +1, owing to the presence of 11 protons in its nucleus.
While on the other hand, the Chlorine atom which is electronegative gains one electron. The resultant electron configuration of the chloride ion is 1s2 2s2 2p6 3s2 3p6.
The chloride ion on gaining an electron gets a charge – 1. The reason is the presence of 17 protons and 18 electrons in the nucleus that makes the charge of the ion as – 1.
The formation of Sodium Chloride can be easily shown with the help of the Lewis Structure.
The Lewis Structure represents only the Valence electrons and also shows the transfer of electrons between the two atoms.
One similar compound is MgCl2 that also lies under the umbrella of the ionic compound. Check out the article on the ionic nature of MgCl2.
Why Na is a cation and Cl is an anion in the NaCl Molecule?
Sodium being an alkali metal is electropositive. It loses one single valence electron, while Chlorine being a nonmetal is electronegative in nature gains one electron.
Sodium loses the single valence electron to form a cation with an octet. This single electron donated by Sodium will be accepted by Chlorine to form an anion with an octet.
This results in the formation of an Ionic compound.
Generally, the Ionic compounds are resulted from the perfect combination of metallic elements present on the left side of the Periodic Table, with the nonmetallic elements which are present on the top of the right side corner of the Periodic Table.
In the crystallized structure of sodium Chloride, each sodium ion is surrounded by six chloride ions while each chloride ion is surrounded by six sodium ions.
Each of the ions will be associated with a complete electron shell which will resemble its nearest inert gas.
For the sodium ion, the electron configuration becomes the same as that of neon, while for the chloride ion the electronic configuration becomes the same as that of argon.
You must also check out the article written on the ionic character of KCl.
From the above discussion it has been clear that Sodium Chloride will form an Ionic compound because of the following reasons :
1. An ionic bond can be formed only by the process of the complete transfer of electrons from one atom to the other. The atom which loses its electrons forms the cation while the atom which accepts electrons forms the anion.
2. The atomic number of Sodium being 11, comprises a total of 11 protons and 11 electrons respectively.
3. The electronic configuration of sodium is going to be similar to that of neon and the resultant electronic configuration is going to be 1s2 2s2 2p6 3s1.
4. There exists one valence electron in the outermost shell of the sodium atom.
5. Sodium has the tendency to lose the electron and the resultant valence shell reaches the octet state which is the most stable state.
6. Sodium being electropositive will lose an electron that results in the ionization of the Sodium. Now sodium will have a charge +1.
7. Chlorine has an atomic number of 17, thus comprised of 17 protons and 17 electrons.
8. The Chlorine atom comprises seven electrons in its valence shell.
9. Therefore, being electronegative in nature, Chlorine has the tendency to accept an electron to complete its octet.
10. This acceptance of a single electron will be able to complete the third shell of Chlorine.
11. The resultant electronic configuration of Chlorine is going to be similar to that of Argon which is 1s2 2s2 2p6 3s2 3p6.
12. The charge of Chlorine becomes as – 1. The transfer of the electron between the Sodium and Chlorine atoms leads to the formation of the Ionic Bond with Na+ and Cl- respectively.