The main difference between covalent and ionic bonds is that ionic bonds occur between two species that are electrostatically attracted to each other, whereas covalent bonds occur covalently through the sharing of electrons between their outer shells.
It is the nature of elements to form bonds between them in order to become stable. Covalent bonds and ionic bonds are two different ways of how elements bond to each other. In general, metallic elements tend to form ionic bonds, while non-metallic elements tend to form covalent bonds.
Key Areas Covered
1. What is an Ionic Bond
– Definition, Features, Role
2. What is a Covalent Bond
– Definition, Features, Role
3. Difference Between Covalent and Ionic Bonds
– Comparison of Key Differences
4. FAQ: Covalent and Ionic Bonds
– Answers to Frequently Asked Questions
Key Terms
Ionic Bond, Covalent Bond
What is an Ionic Bond
Ionic bonds are a result of electrostatic forces between atoms that get attracted toward each other due to the possession of opposite electrical charges. Each element tries to accomplish a stable electronic configuration at the outer shell (electronic configuration of the noble gases). Having a noble gas electronic configuration prevents atoms from further reactions as they are already stable. Therefore, elements in nature that are not electronically stable tend to give away any extra electrons or accept the missing number of electrons in order to achieve the closest noble gas configuration. Ions are formed under this principle.
Atoms that tend to give away their extra electrons to attain stable electronic configuration end up being positively charged (due to the loss of negatively charged electrons), and these are called “cations”. Similarly, when an atom accepts electrons to complete the final shell configuration, they become negatively charged (due to the increase in negatively charged electrons), and these are called “anions”. Therefore by definition, ionic bonds are formed between anions and cations.
Ionic compounds tend to be solid in nature, and they usually have very high melting points as the ionic bonds are quite strong; in fact, it is the strongest type of chemical bond that exists. Ions can be atomic or molecular in nature. i.e., CO32- is a molecular anion. A few examples of ionic compounds are NaCl, MgCl2, etc.
What is a Covalent Bond
Covalent bonds are much weaker than ionic bonds, and therefore, most of the covalent compounds exist in the gaseous phase. As mentioned above, the atoms need to form electrons in order to attain a stable electronic configuration. The third way of obtaining this (apart from giving away and accepting electrons, as mentioned in the case of the ionic bonds) is through the sharing of electrons. In this method, both atoms taking part in the formation of the compound get to share the required number of electrons (usually with one donor atom and an acceptor atom looking for the same amount of electrons) in a common overlapped orbital space. It is important that the atoms come into close proximity to each other for the orbital overlap before the electron sharing takes place. Therefore, in this case, neither atom will be electrically charged but will remain neutral.
The overlapping can take place in a linear fashion or in a parallel manner. When it is directed and linear, the bond type is called a “σ bond”, and in the other case, it is a “π bond”. Furthermore, this sharing of electrons can take place between similar types of atoms as well as different types of atoms. When the involved atoms are similar, the resulting compound is called a ‘diatomic molecule’. H2O, CO2, etc., are some common examples.
Difference Between Covalent and Ionic Bonds
Definition
Ionic bonds are bonds that occur when the atoms are electrostatically attracted toward each other, while covalent bonds are bonds that occur when the electrons are shared between the atoms involved in the formation.
Species involved
While ionic bonds occur through the interaction between cations and anions, covalent bonds occur through the interaction of neutral atoms.
Strength
Ionic bonds are the strongest type of chemical bond, so most compounds remain solid with very high melting points. In contrast, covalent bonds are quite weak; hence, most compounds exist in the gaseous phase.
FAQ: Covalent and Ionic Bonds
What are some examples of covalent and ionic bonds?
Ionic bonds are seen in sodium chloride (NaCl) and magnesium oxide (MgO), while covalent bonds are commonly seen in hydrogen (H2) and water (H2O).
Which is stronger: ionic or covalent bonds?
Ionic bonds are stronger than covalent bonds because they involve the electrostatic attraction between oppositely charged ions, which are more strongly attracted to each other due to the complete transfer of electrons.
Why are covalent bonds weak?
Compared to ionic bonds, covalent bonds are generally weaker. Ionic bonds involve the complete transfer of electrons between atoms, resulting in strong electrostatic attractions between oppositely charged ions, which are typically stronger than the shared electrons in covalent bonds.
Conclusion
The main difference between covalent and ionic bonds is that covalent bonds involve the sharing of electrons between atoms, while ionic bonds involve the transfer of electrons from one atom to another, resulting in the formation of oppositely charged ions.
Image Courtesy:
1. “207 Ionic Bonding-01” by OpenStax College – Anatomy & Physiology, Connexions Web site(CC BY 3.0) via Wikimedia Commons
2. “Covalent” by DynaBlast – Created with Inkscape. (CC BY-SA 2.5) via Wikimedia Commons
