Ionic Bond or Electrovalent Bond - Definition, Examples, Properties, Principal, FAQs

Ionic, or electrovalent, bonds are part of the basics of chemistry. These bonds are formed by electrostatic attraction between ions, which means an atom or molecule has either gained or lost an electron to give it a net electrical charge. Generally, ionic bonds form between metals and nonmetals. Because metals' electronegativity is always less, they can easily lose their electrons and become positively charged cations.

Understanding Ionic Bonds

Atoms form ionic bonds through electron transfer to other atoms, developing charged ions in the process. For example, when the electron is lost by a metal atom, like sodium, Na, it becomes a positively charged ion, Na⁺. On the other hand, when a nonmetal atom, let's say chlorine, Cl, gains an electron, the atom it forms becomes a negatively charged ion, Cl⁻. This strong electrostatic force of attraction between these oppositely charged ions leads to the forming of an ionic bond and results in an ionic compound like common salt, which is sodium chloride or NaCl

Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence shell, and an anion (a negative ion) forms when a neutral atom gains one or more electrons in its valence shell. Compounds composed of ions are called ionic compounds (or salts), and their constituent ions are held together by ionic bonds or electrostatic forces of attraction between oppositely charged cations and anions. Ionic solids exhibit a crystalline structure and tend to be rigid and brittle; they also have high melting and boiling points, which suggests that ionic bonds are very strong. Ionic solids are poor conductors of electricity as the strength of ionic bonds is very strong and it prevents the ions from moving freely in the solid state. Most ionic solids, however, dissolve readily in water. Once dissolved or melted, ionic compounds are excellent conductors of electricity and heat because, in the liquid state, these ions can move freely.

Related Topics Link

• Valence Bond Theory
• Formation of Ionic Compounds

The Formation of Ionic Compounds

Binary ionic compounds are composed just of two elements i.e., a metal (which forms the cations) and a nonmetal (which forms the anions). For example, NaCl is a binary ionic compound. Many metallic elements have relatively low ionization potentials and lose electrons easily. These elements lie to the left in a period or near the bottom of a group on the periodic table. Nonmetal atoms have relatively high electron affinities and thus readily gain electrons lost by metal atoms, thereby filling their valence shells. Nonmetallic elements are found in the upper-right corner of the periodic table.

It is important to consider that the formula for an ionic compound does not represent the physical arrangement of its ions. For example, sodium chloride (NaCl) “molecule”, because there is not a single ionic bond between any particular pair of sodium and chloride ions. The attractive forces between ions are isotropic i.e., the same in all directions in other words, any particular ion is equally attracted to all of the nearby ions of opposite charge. This results in the ions arranging themselves into a tightly bound, three-dimensional lattice structure. Sodium chloride, for example, consists of a regular arrangement of equal numbers of Na⁺ cations and Cl^– anions as shown in the figure.

The strong electrostatic force of attraction between Na⁺ and Cl^– ions holds them tightly together in solid NaCl. It requires 769 kJ of energy to dissociate one mole of solid NaCl into separate gaseous Na⁺ and Cl^– ions:

NaCl(s) $\longrightarrow$ Na⁺(g)+Cl^- $\Delta $H=769 kJ

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Types and Features of Ionic Bonds

Ions can also be classified according to the nature of the elements taking part in the bond. They are mainly formed between metals and nonmetals. The metal loses electrons, and the nonmetal gets them. A very fine example of an ionic bond is that formed between sodium and chlorine to form NaCl.

The main features of ionic bonds are:

1. Ion Formation: Metals lose electrons to form cations; nonmetals gain electrons to form anions.
2. High MP and BP: The melting and boiling points of ionic compounds are generally high because of the strong ionic attractions involved.
3. Electrical Conductivity: A certain conductivity results when ionic compounds are melted or dissolved in water, as a result of the free movement of the ions.
4. Brittleness: Ionic compounds are, for the most part, brittle and shatter upon application of stress.

All these properties underline the importance of ionic bonds in chemical processes and the applications of those in various spheres.

Also read :

• NCERT notes Class 11 Chemistry Chapter 4 Chemical Bonding and Molecular Structure
• NCERT solutions for Class 11 Chemistry Chapter 4 Chemical Bonding and Molecular Structure
• NCERT Exemplar Class 11 Chemistry Solutions Chapter 4 Chemical Bonding and Molecular Structure

Ionic Bonds and Their Applications in Real Life

Ionic bonds are very important both in everyday life and in many branches of science. Table salt, or sodium chloride, is an ionic compound that is widely used in the culinary arts as flavoring in foods and as a preservative. Many fertilizers, such as ammonium nitrate, are ionic compounds that provide plants with critical nutrients they need to grow.

In materials science, the ionic bond forms ceramics and glass—basic constituents of construction and manufacturing. Ionic compounds play a lead role in electronics; for instance, in a lithium-ion battery, it is even through ionic interactions that energy is stored and passed.

Recommended topic video on (Ionic Bond or Electrovalent Bond )

Some Solved Examples

Example 1

Which of the following compounds contain(s) no covalent bond(s) ?
KCl, PH₃, O₂, B₂H₆, H₂SO₄

1)KCl, B₂H₆,

2)KCl, B₂H₆, PH₃,

3)KCl, H₂SO₄

4) (correct)KCl

Solution

As we learned in the concept

Ionic Bonding -

The formation of an ionic bond takes place between a metal and a non-metal by the transfer of electrons.

- wherein

e.g $\mathrm{NaCl}, \mathrm{CaCl}_2$ etc.

$\mathrm{KCl} \Rightarrow$Ionic compound

Hence, the answer is an option (4).

Example 2

The atomic number of four elementsP,Q,R,S are6,8,10 and 12 respectively.
The two elements which can react to form ionic compounds are:

1)$P$ and $S$

2)$Q$ and $R$

3)$P$ and $R$

4) (correct)$Q$ and $S$

Solution

Q atom’s electronic configuration is 2,6, and the S atom is 2,8,2. Therefore, S has 2 electrons in its outermost shell so that it will lose 2 electrons to Q, and both will attain inert gas configuration.

Hence, the answer is the option (4).

Example 3

What is the electronic configuration of calcium ion (Ca²⁺)

1)2,8

2)2,8,2

3)2,8,4

4) (correct)2,8,8

Solution

The atomic number of calcium is 20, so its electronic configuration is 2,8,8,2, and it has 2 electrons in the outermost shell.

Therefore to form calcium ion (Ca²⁺)
Calcium will lose 2 electrons and its configuration becomes 2,8,8.

Hence, the answer is the option (4).

Example 4

Which of the following can form an Ionic bond?

1)B and Cl

2) (correct)Mg and Cl

3)Be and H

4)Si and O

Solution

Mg has two valence electrons while Cl has seven valence electrons. Hence, one Mg atom will lose two electrons which will be gained by two Cl atoms, and the ionic compound MgCl₂ will be formed.

Hence, the answer is the option (2).

Example 5

Which one among the elements generally doesn't form an ionic compound?

1)N

2) (correct)Li

3)Na

4)Cr

Solution

Nature of bonding in metals -

The bonding among metal atoms cannot be ionic, covalent, or van der Waals.

Li is a metal but it receives an unusual amount of attraction from their respective nucleus compared to other members of the group. This is because it has its last electron in 2s orbital which is nearest to the nucleus compared to other members. This leads to higher ionization enthalpy and lesser ionic character

Hence, the answer is the option (2).

Summary

While explaining the characteristics of ionic compounds, some of the major physical properties related to ionic compounds that can be taken into consideration would be high melting and boiling points, electrical conductivity, and crystalline structures—physical properties underpinning their role in both natural and industrial processes.

NCERT Chemistry Notes:

• NCERT Notes Class 11th Chemistry
• NCERT Notes Class 12th Chemistry
• NCERT Notes For All Subjects

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