Difference Between Ionic and Covalent Bond

Edited by Diffzy | Updated on: September 20, 2022

       

Difference Between Ionic and Covalent Bond Difference Between Ionic and Covalent Bond

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Introduction

Chemistry is a subject that intrigues the interest of hundreds of people. The different molecules, their interactions with each other, the heat energy, the kinetic energy, and other related topics enhance our knowledge about our surroundings. We get answers to our many basic chemistry questions, such as, what is boiling? What is condensation? How do the water molecules attach to each other in different states, be it the solid-state, liquid state, or gaseous state? What is the bonding between the molecules called?

Then we even study the different types of bonds in chemistry such as the ionic bond, covalent bond, the forces of attraction between the particles, hydrogen bond, etc.

But have you ever thought about the in-depth differences between any of these bonds? Have you ever tried to read and learn more about them? Here, let’s discuss the differences that exist between two types of bonds, namely, the ionic bond and the covalent bond.   

Ionic Bond vs. Covalent Bond

In order to understand the Ionic Bond and the Covalent Bond differences, we first need to know what is a chemical bond. A chemical bond is an attractive force that holds or binds the atoms or even a group of atoms together.

An ionic bond is an electrostatic force of attraction that exists between two oppositely charged ions. Mostly ionic bonds join metals to non-metals. On the other hand, a covalent bond is a shared bond. It joins non-metals to non-metals.

Now, you might be thinking that what is the difference between a metal and a non-metal?

Here goes your answer, a metal is an element that forms electropositive ions by donating the electrons to form any bond. Metals can be found in the periodic table under the category of alkali metals, transition metals, and alkaline earth metals. Now, based on the group to which they belong, the metals can lose either 1 or 2, or more of their electrons to form the positive ions.

On the other hand, non-metals are those elements that consist of partially filled electrons in their outermost shell out of the many shells. Because they have a large number of valence electrons, they tend to attract other electrons from their neighbouring atoms and then form anions. Hence, we can say that non-metals are electronegative elements in nature (Metals and Non-Metals: Differences, Physical and Chemical Properties, n.d.).    

Difference Between Ionic Bond and Covalent Bond in Tabular Form

Table: Ionic Bond vs. Covalent Bond
Parameters of Comparison
Ionic Bond
Covalent Bond
Occurrence
It happens during the transfer of electrons.
It happens when two atoms share the valence electrons.
Conductivity
It has low conductivity.
It has even lower conductivity than the ionic bond.
Direction
It is a non-directional bond.
It is a directional bond.
Melting point
It has a higher melting point.
It has a lower melting point
Boiling point
It has a higher boiling point.
It has a lower boiling point (Difference Between Ionic, Covalent, and Metallic Bonds, n.d.).

What is Ionic Bond?

An Ionic Bond is a type of chemical bonding that consists of the electrostatic attraction between two oppositely charged ions or between two atoms that have different electronegativities. Cations are positively charged atoms that tend to give away their surplus electrons to achieve a stable electronic configuration (owing to the loss of negatively charged electrons). When an atom receives electrons to complete the final shell configuration, it becomes negatively charged (due to the increase in negatively charged electrons), and these are referred to as "anions." Thus, Ionic bonds are created between anions and cations by definition (Difference Between Covalent and Ionic Bonds, 2015).

Ionic compounds have a tendency to conduct electricity only in molten states, not when they’re in their solid-state. Ionic compounds shave a high melting point which depends on the charge of the ions that they’re composed of. The higher the charges, the stronger will be the cohesive forces and the higher will be the melting point.     

Ionic compounds are also soluble in water. Thus, the stronger the cohesive forces will be, and the lower the solubility will be. Now, let’s learn about the formation of the Ionic Bond.

Formation of Ionic Bond

Ionic bonding can occur as a result of a redox reaction in which atoms of a low-ionization-energy element (typically metal) give up part of their electrons to achieve a stable electron configuration. Cations are generated as a result of this process. An atom of a different element (typically nonmetal) with a higher electron affinity absorbs one or more electrons in order to achieve a stable electron configuration, and the atom becomes an anion after accepting electrons. For elements in the s-block and p-block, the stable electron configuration is often one of the noble gases, with specific stable electron configurations for d-block and f-block elements. Because of the electrostatic attraction between anions and cations, a solid with a crystallographic lattice in which the ions are stacked in an alternating pattern form.

Sodium chloride, for example, is popular table salt. When sodium (Na) and chlorine (Cl) are mixed, the sodium atoms lose an electron and form cations (Na+), while the chlorine atoms gain an electron and form anions (Cl). These ions are subsequently drawn together in a 1:1 to produce sodium chloride (NaCl).

However, stringent ratios between anions and cations are observed to maintain charge neutrality, hence ionic compounds, despite not being molecular compounds, generally follow the requirements of stoichiometry. This may no longer be the case for compounds that are transitional to alloys and have mixed ionic and metallic interactions. Non-stoichiometric compounds are formed by many sulphides, for example (Ionic Bonding, n.d.).

Different Ionic Structures

In the solid-state, ionic compounds form lattice structures. The relative charges and sizes of the ions are the two most important factors in determining the lattice's shape. Many alkali halides and binary oxides, such as magnesium oxide, have structures that are similar to those of the rock salt sodium chloride. Pauling's criteria are a set of guidelines for predicting and reasoning ionic crystal formations (Ionic Bonding, n.d.).

What is a Covalent Bond?

A chemical link involving the sharing of electron pairs between atoms is known as a covalent bond. These electron pairs are called shared pairs or bonding pairs, and covalent bonding is the stable equilibrium of attractive and repulsive forces between atoms when they share electrons. For example, the hydrogen atoms in the molecule H2 share two electrons via covalent bonding. The greatest covalency exists amongst atoms with equal electronegativities. Covalent bonding does not necessarily need that the two atoms are of the same element, only that their electronegativity is comparable. Delocalized covalent bonding is defined as the sharing of electrons between more than two atoms.

Types of Covalent Bond

Except for s orbitals, atomic orbitals have distinct directional features that lead to several forms of covalent bonding. The strongest covalent bonds are sigma (σ) bonds, which are formed by the head-on overlapping of orbitals on two different atoms. A sigma bond is usually a single bond. Due to lateral overlap between p (or d) orbitals, pi (π) bonds are weaker. A double bond between two atoms is made up of one σ and one π bond, while a triple bond is made up of one σ and two π bonds.

The electronegativity of the linked atoms, which defines the chemical polarity of the bond, also affects covalent bonding. Nonpolar covalent bonds, such as H–H, are formed when two atoms have similar electronegativity. In the case of HCl, an uneven connection produces a polar covalent bond. Polarity, on the other hand, necessitates geometric asymmetry, else dipoles will cancel out, resulting in a non-polar molecule.

Different Covalent Structures

Individual molecules, molecular structures, complex molecular structures, and enormous covalent structures are all examples of structures for covalent substances. Molecules have strong forces that bind the atoms together, but the attractive forces between molecules are often minimal. Gases, such as HCl, SO2, CO2, and CH4, are examples of covalent compounds. There exist weak forces of attraction in molecular structures. Low-boiling-temperature liquids (such as ethanol) and low-melting-temperature solids are examples of covalent substances (such as iodine and solid CO2). Synthetic polymers such as polyethylene and nylon, as well as biopolymers such as proteins and starch, have huge numbers of atoms linked by covalent bonds in chains.

Large numbers of atoms are linked in sheets (such as graphite) or 3-dimensional structures in network covalent structures (or giant covalent structures such as diamond and quartz). These materials have high melting and boiling points, are brittle, and have a high electrical resistivity. Large macromolecular structures are frequently formed by elements with high electronegativity and the capacity to establish three or four electron pair bonds (Covalent Bond, n.d.).

Main Differences Between Ionic Bond and Covalent Bond In Points

  • An ionic bond is simply a bond that exists between a metal and a non-metal. Because the nonmetal attracts the electron, it's as if the metal gives it one of its electrons. On the other hand, a covalent bond is that bond that exists between two non-metals that have similar or the same electronegativities.
  • In an ionic bond, the polarity is very high. On the contrary, the polarity is low in a covalent bond. What is Polarity? The physical properties of compounds such as boiling points, melting points, and solubilities are all examples of polarity. The interaction between molecules and atoms with different electronegativities causes polarity in bonds.
  • Ionic Bonds have no definite shape. But covalent bonds do have a definite shape.
  • The state at room temperature of an ionic bond is mostly solid. On the other hand, the state at room temperature for covalent bonds is either liquid or gaseous (Helmenstine, 2020).
  • The molecular geometry around each atom in covalent bonding is regulated by valence shell electron pair repulsion VSEPR principles, whereas the geometry in ionic materials is determined by maximum packing laws.
  • Purely ionic bonding is impossible because the proximity of the parties involved allows for some degree of electron density sharing. As a result, all ionic bonding has a covalent component. When the ionic character is stronger than the covalent character, bonding is considered ionic.
  • Polar covalent bonds are those that are partially ionic and partially covalent. Na–Cl and Mg-O interactions, for example, have only a few percent covalency, but Si–O bonds are commonly 50% ionic and 50% covalent (Ionic Bonding, n.d.).
  • Whenever ionic bonding occurs in the solid (or liquid) form, it is impossible to speak of a singular "ionic bond" between two individual atoms since the cohesive forces that hold the lattice together are of a much more collective nature. In the case of covalent bonding, however, we can frequently speak about a separate link confined between two specific atoms (Ionic Bonding, n.d.).

Conclusion

To conclude, it can be said that it’s very important to know and understand the differences between ionic bonds and covalent bonds. This is because, in chemistry, everything begins with the interactions between the bonds among the molecules. To find out the reason behind water being in a liquid state at room temperature, or the reason behind it getting boiled at 100 degrees Celsius, all such basic questions require a common understanding of chemical bonds. Hence, by beginning from scratch and delving into the interactions between the several different molecules, one can easily thorough the differences between an ionic bond and a covalent bond.

In order to concise the differences between an ionic bond and a covalent bond, it can be said that an ionic bond is an interaction between two atoms (one metal and the other a non-metal), on the other hand, a covalent bond joins or brings together two non-metals. In ionic bonding, at the outer shell, each constituent seeks to achieve a stable electrical configuration. The electrical structure of a noble gas precludes atoms from undergoing further reactions because they are already stable. As a result, in order to reach the nearest noble gas configuration, elements that are not electrically stable tend to give away any surplus electrons or take the missing number of electrons. This concept causes ions to form.

References

  • Covalent Bond. (n.d.). Retrieved from Wikipedia: https://en.wikipedia.org/wiki/Covalent_bond
  • Helmenstine, A. M. (2020, January 23). Ionic vs Covalent Bonds- Understand the Difference. Retrieved from ThoughtCo.: https://www.thoughtco.com/ionic-and-covalent-chemical-bond-differences-606097
  • Ionic Bonding. (n.d.). Retrieved from Wikipedia: https://en.wikipedia.org/wiki/Ionic_bonding#:~:text=Ionic%20bonding%20is%20a%20type%20of%20chemical%20bonding,bonds%20along%20with%20Covalent%20bond%20and%20Metallic%20bonding.

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