Is Sodium chloride (NaCl) ionic or covalent? Types of bond in NaCl

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Is sodium chloride (NaCl) ionic or covalent?

Sodium chloride composed of sodium and chlorine atom is 1:1 ratio and have a chemical formula NaCl. It is common salt we use in our daily life and it is most responsible for the salinity of seawater. It appears as a white crystalline solid without any odor. It is also commonly used as condiments and food preservatives.

In this article, we will discuss Is sodium chloride (NaCl) ionic or covalent? chemical bond, bonding formation, what type of bond is present in NaCl, etc.

So, Is NaCl ionic or covalent? NaCl is an ionic compound because the bond formed between sodium and the chlorine atom is ionic in nature, it is formed due to the transfer of electrons from Na to Cl, which results in the formation of ions(Na+ and Cl), later these ions are attracted by the electrostatic force of attraction and forms the ionic bond.

Let’s read in detail, Why sodium chloride (NaCl) is an ionic compound? How ionic bonds formation takes place in NaCl? What factors affect the ionic bond formation in NaCl and everything!

Name of MoleculeSodium chloride
Chemical formulaNaCl
Ionic or Covalent?Ionic
Molar mass58.443 g/mol
NatureNeutral
pH value7

Why Sodium chloride (NaCl) is an ionic compound?

An ionic compound is a compound that involves the exchange of valence electrons of one or more atoms to another atom usually electron is a transfer by metal and acceptance by non-metal.

After exchanging the electrons, the ions are formed with positive and negative charges, then these ions hold together by the electrostatic force of attraction which leads to the formation of ionic bonds in between the atoms.

So, In the case of the NaCl molecule, sodium is a metal that belongs to the alkali metal group and chlorine is a nonmetal that belongs to the halogen family.

Sodium metal completely transfers the one-electron and chlorine as nonmetal will accept this electron. All this leads to the formation of ions (Na+ and Cl), both these ions will be held together by the electrostatic force of attraction, and eventually, a bond is formed which is called an ionic bond.

Ionic bond formation in NaCl (sodium chloride)

Hence, the complete transferring of electrons(from Na to Cl) and formation of an ionic bond between Na+ and Cl shows why Sodium chloride (NaCl) is an ionic compound in nature.

Examples of some more ionic compounds – MgO, Na2O, MgCl2, etc.

Also Read:

How ionic bond formation takes place in NaCl (sodium chloride)?

In simple words, an ionic bond is formed by giving and take of electrons between metals and nonmetals.

The formation of ionic bonds in NaCl usually involves three processes.

(1). Formation of cation(Na+)

The cation is a positively charged ion formed when a metal loses its electron. So, in the case of the NaCl ionic bond formation, sodium metal will lose the one-electron and forms a positively charged Na+ ion.

But why sodium metal is losing the electrons? Because it has low ionization energy and every element in chemistry wants to achieve a stable octet configuration i.e. having 8 electrons in the outermost shell.

So, sodium metal has 11 electrons means its electronic configuration is (2, 8, 1). By losing one electron, its electronic configuration will be (2, 8). So, now it has an electronic configuration close to the noble gas configuration and has 8 electrons in the outermost shell.

formation of cation in NaCl ionic compound

Therefore, sodium metal attains stability by losing one electron from itself and forms a positively charged Na+ ion.

(2). Formation of the anion(Cl)

An anion is a negatively charged ion formed when a nonmetal gains the electron. So, in the case of NaCl ionic bond formation, the chlorine atom will accept the electron from metal(sodium) and forms a negatively charged Cl ion.

But why does chlorine accepts the electron? This is because chlorine has 17 electrons and has an electronic configuration (2, 8, 7). By gaining one electron from metal, it attains stability because now its electronic configuration becomes (2, 8, 8), hence, it has 8 electrons in the outermost shell.

formation of anion in NaCl ionic compound

Therefore, chlorine non-metal attains stability by gaining one electron from sodium metal and forms a negatively charged Cl ion.

(3). Electrostatic force attraction between ions(Na+ and Cl)

This is the last step involves in the formation of ionic bonds in NaCl. After the formation of Na+ and Cl, these positive and negative charges will attract each other with the help of the electrostatic force of attraction generated between them.

Electrostatic force is non-contace force that attract the positive and negative charged particles or objects without touching them.

As we already know, the opposite charged particles or ions will always attract each other, hence, the Na+ and Cl ion will attract each other and be linked together by the electrostatic force of attraction, and all these caused a bond formation between Na+ and Cl ion which is called ionic bond or electrovalent bond.

Ionic bonding in NaCl (sodium chloride)

Why NaCl not have a covalent bond?

A covalent bond is completely different from an ionic bond.

A covalent bond is formed when sharing of electrons occurs between the atoms to achieve stability. 

Usually, covalent bonds formed between the two nonmetals, between p-block and p-block, and formed when electronegativity difference between atoms exist less than 1.7.

Examples of some compounds that form covalent bonds – H2O, NH3, H2S, SO2, NO2, AlCl3, etc.

Also Read:

So, why does NaCl not forms a covalent bond? There is a lot of reasons exist why covalent bond can’t be formed in NaCl compound. But we will discuss some important ones only.

First of all, NaCl atoms have positive and negative charge occurs by the complete transfer of an electron, hence, it forms the ions.

So, in the NaCl compound, there is no sharing of electrons involves, sodium transfer the electron and chlorine accept the electron to achieve the stability by completing the octet. And a bond is formed between these ions is called an ionic bond.

Is sodium chloride (NaCl) covalent or ionic in nature?

⇒ Sodium is a metal that has an electronegativity value equal to 0.93 and chlorine is a nonmetal that has an electronegativity value equal to 3.16.

Hence, the gap of electronegativity difference between sodium and chlorine atom is (3.16 – 0.93) = 2.23 that is huge.

So, according to the Pauling scale-

  • If the difference of electronegativity between the atoms is more than 1.7, then the bond formed between these atoms is ionic in nature.
  • If the difference of electronegativity between the atoms is less than 1.7, then the bond formed between these atoms is covalent in nature.

pauling scale for chemical bonds

So, in the case of NaCl, the difference of electronegativity between sodium and chlorine atom exist more than 1.7, hence, according to the Pauling scale, the bond formed between the sodium and chlorine atom(Na-Cl) is ionic in nature.

Energy involving in the process of ionic bond formation in NaCl?

“A chemical bond is a bond that formed by either sharing of electrons or transferring of electrons”. When a chemical bond is formed it releases energy, which helps to attain stability between the new bonds.

The formation of a bond releases the energy whereas the breaking of the bond absorbs the energy.

There are three types of energy involved in the process of ionic bond formation in NaCl.

(a). Ionization enthalpy

(b). Electron gain enthalpy

(c). Lattice energy

⇒ Ionization enthalpy

Ionization enthalpy is the amount of energy required to remove the loose electron of an isolated gaseous atom from its outermost shell, then convert it into a gaseous positive ion.

Ionization enthalpy is always positive and occurs when an electron loses from the atom.

So, in the case of ionic bond formation in NaCl, when an electron is loosed or released from the sodium metal then the energy associated with it is ionization enthalpy.

energy required during the process of cation formation in NaCl

⇒ Electron gain enthalpy

This energy is just opposite to ionization energy. The electron gain enthalpy is the enthalpy that occurs when an electron is added to an isolated atom in the gaseous phase, then convert this isolated atom into a gaseous negative ion.

The electron gain enthalpy may be positive or negative but most of the time it is negative. It should be noted that electron gain enthalpy is the most negative for a chlorine atom.

So, in the case of ionic bond formation in NaCl, when an electron is accepted or is added to the chlorine atom then energy associated with it is electron gain enthalpy.

energy release during the process of anion formation in NaCl

⇒ Lattice energy

The lattice energy is the energy that releases when 1 mole of an ionic bond is formed from adding gaseous anion and cation.

The more the lattice energy releases during the formation of an ionic bond, the higher is the stability of that bond.

So, in the case of ionic bond formation in NaCl, when cation(Na+) is attracted by anion(Cl), then some amount of energy is released which is called lattice energy.

energy releases during the process of ionic bond formation in NaCl

As you see in the above figure when 1 mole of cation(Na+) diffuses with one mole of the anion(Cl) then one mole of solid(NaCl) is formed.

And the energy released during the formation of ionic bonds in NaCl is lattice energy.

Factors favoring the ionic bond formation in NaCl?

There are three most important factors that can favor ionic bond formation in NaCl compounds or any other ionic compounds.

(a). Ionization energy

The lower the ionization potential or energy involves, it is easier to lose the electrons from an isolated gaseous atom to form a cation.

⇒ A(g) → A+(g) + e

So, ionization energy should be low to forms the cation ion easily.

(b). Electron gain enthalpy

The higher the negative electron gain enthalpy involves, the easier it is to add the electron to the gaseous isolated atom to forms an anion.

⇒ B(g) + e → B(g)

So, the electron gain enthalpy must be higher to forms anion ion easily.

(c). Lattice energy

The higher the lattice energy, the more is the stability of an ionic compound.

Or the higher the lattice energy released during the attraction of cation and anion, the greater is the tendency of forming the ionic compound.

⇒ A+ B → A+B + Lattice energy

The most favorable factor or condition for the formation of ionic bond easily is-

factor favoring for formation of ionic bond easily

The sum of lattice energy and electron gain enthalpy must be higher than the ionization energy to easily form the ionic bond between the atoms.

Properties of sodium chloride

  • The molar mass of NaCl is 58.443 g/mol.
  • It is odorless and appears as cubic crystals.
  • It has a melting point of 800 °C and a boiling point of 1,465 °C.
  • It is soluble in water and a good conductor of electricity.
  • It has a density of 2.165 g/cm3.
  • It has a crystal structure of Face-centered cubic.
  • It has a coordination number of 6 and coordination geometry for Na+ and Cl- is octahedral.
  • It decomposes at high temperatures to produce toxic fumes of Na2O and HCl.
  • At low concentrations, sodium chloride is non-toxic and non-hazardous.
  • 100 g of NaCl contains 39.34 g Na and 60.66 g Cl.
  • The pH of sodium chloride solution is 7 due to the weak basicity of Cl- ion.

Uses of sodium chloride

  1. In the metals extraction process, sodium chloride acts as an electrolyte and reduces the melting point of minerals.
  2. It is used in the Chlor-alkali process to produce chlorine, sodium hydroxide, and hydrogen.
  3. It is used as condiments and food preservatives.
  4. It is used for “de-icing of roadways in sub-freezing weather”.
  5. It is used in the production of sodium sulfate and hydrochloric acid.
  6. It is used to enhance the natural color or taste of food.
  7. It is used to remove stains and grease.
  8. It is also used as a drying agent.

FAQ

Does NaCl have a covalent bond also or it is 100% ionic?

No compound in the universe is 100% ionic, leave aside NaCl. But NaCl compound is predominantly ionic which means it is largely dominated by ionic character. 

In theoretically, we can say NaCl is close to 100% ionic but practically it is not, it has some covalent character also.

What type of bond is present in NaCl (sodium chloride)?

Ionic bond present in NaCl compound due to the large difference of electronegativity exist between sodium and chlorine atom. Almost more than 2.1, that shows an ionic character in compounds according to the Pauling scale.

Why (sodium chloride) NaCl is an ionic rather than covalent in nature?

Covalent bonds occur when sharing of electrons exist between the atoms but in the case of the NaCl compound, the sodium atom completely transfers the electron to the chlorine atom, hence, there is no sharing between sodium and chlorine atom exist.

Hence, the NaCl compounds can’t be covalent in nature. Also, for a covalent bond, the difference of electronegativity should be less than 1.7 but in the case of NaCl, the difference of electronegativity between sodium and chlorine is more than 2.2, hence, NaCl is ionic in nature rather than covalent.

Why does sodium metal lose electrons and chlorine gains the electron to form an ionic bond in NaCl?

This is because sodium is a metal that has low ionization energy, metals are more prone to lose electrons to achieve the octet.

As sodium metal has the electronic configuration (2, 8, 1), so, for sodium, it is easier to lose the one electron to achieve octet and hence, attains stability.

A nonmetal has high ionization energy and large electronegativity, they can easily accept the electrons to achieve the octet.

As chlorine nonmetal has the electronic configuration (2, 8, 7), so, gaining one electron makes its electron configuration (2, 8, 8), hence, achieve the octet and attains stability.

How transfer of electrons takes place from Na to Cl, to forms an ionic bond in NaCl?

The sodium metal loses the electron and forms a positively charged Na+ cation whereas chlorine nonmetal gains the electron and forms a negatively charged Cl anion.

The Na+ and Cl ions are linked together by the electrostatic force of attraction and during this force of attraction, a bond is formed which is called an ionic or electrovalent bond.

What is the most favorable condition for the formation of ionic bonds in NaCl or any other compound?

The sum of lattice energy and electron gain enthalpy must be higher than ionization energy to easily form the ionic bond in any compound.

Summary

That’s all, we have done almost all concepts and possible explanations about Is sodium chloride (NaCl) ionic or covalent? Bond types in NaCl, why NaCl is ionic and not a covalent compound? How ionic bond is formed in NaCl? What type of energy releases during the formation of ionic bonds in sodium chloride? Factor favoring the ionic nature in NaCl (sodium chloride).

Let’s take a quick overview of all the things we have studied in this article.

  • Is sodium chloride (NaCl) ionic or covalent? Sodium chloride (NaCl) is an ionic compound because of the complete transfer of electrons taking place from sodium metal to chlorine nonmetal, the (Na+ and Cl ions) are held together by the electrostatic force of attraction that caused the formation of ionic bond in NaCl.
  • Three types of energy are involved in the process of ionic bond formation in sodium chloride (NaCl) – (1). Ionization energy (2). Electron gain enthalpy (3). Lattice energy.
  • NaCl is not truly 100% ionic, in fact, no other compound in the universe exists 100% ionic in nature.
  • Energy is released during the formation of an ionic bond in NaCl which is called lattice energy.
  • The difference in electronegativity between Chlorine(3.16) and Sodium(0.93) is 3.16–0.93=2.23 which is higher than 1.7, hence, according to the Pauling scale, the bond formed between chlorine and sodium atom is ionic in nature.
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