This post describes 5 differences between ionic and covalent bonding.
1. Elements
Ionic bonds form between metals and non-metals. Covalent bonds form between non-metals.
This means that covalent bonds can form between atoms of the same element, such as two hydrogen atoms. The same cannot happen for ionic bonds.
Examples of ionic compounds include sodium chloride (NaCl), lithium bromide (LiBr) and magnesium oxide (MgO). Examples of covalent compounds include carbon dioxide (CO2), water (H2O) and ozone (O3).
2. Electrons
Although both ionic and covalent bonds both involve valence electrons, there is a difference in how the electrons are involved.
Ionic bonds involve the transfer of electrons. Covalent bonds involve electrons being shared between atoms.
For example, in sodium chloride (an ionic compound) the valence electron from a sodium atom transfers to a chlorine atom. This forms a positive sodium ion and a negative chlorine ion which are held together by strong electrostatic attractions.
To see how to draw dot and cross diagrams for ionic compounds click here.
Whereas, for a hydrogen molecule (a covalent molecule) the valence electron of one hydrogen atom is shared with the valence electron of another hydrogen atom. The shared pair of electrons are attracted to both of the hydrogen nuclei.
To see how to draw dot and cross diagrams for covalent compounds click here.
3. Direction
Ionic bonds act in every direction. Covalent bonds are directional and only act between the two atoms involved in the bond.
For example, in sodium chloride (an ionic compound) each chlorine ion surrounds six sodium ions and each sodium ion surrounds six chlorine ions. The ions aren’t solely bonded to the atom from which they received/donated an electron.
Whereas, for a hydrogen molecule (a covalent molecule) the bond only acts between the two hydrogen atoms that share electrons.
4. Conduction
Covalent compounds can’t conduct electricity as they don’t contain any free mobile electrons or ions.
As a solid, ionic compounds also have no free mobile electrons or ions and can’t conduct electricity. However, unlike covalent compounds, when dissolved in water or when in their molten state they can conduct electricity.
This is because the ions are free and are able to move allowing electricity to be conducted.
5. Melting and Boiling Points
The melting points of compounds with ionic bonds are usually higher than those with covalent bonds. Likewise, the boiling point of compounds with ionic bonds is usually higher than those with covalent bonds.
This is because, in general, more energy is required to break ionic bonds than covalent bonds.
Hence why ionic compounds are usually solid at room temperature and covalent compounds are usually liquid or gaseous.
To learn more about covalent bonding click here.
To learn more about ionic bonding click here.
Please leave any questions in the comments below and feel free to leave any requests for topics that aren’t currently covered on the site. You can stay up to date with the latest posts by following me on Instagram or Pinterest. Click on one of the following categories or use the search bar at the bottom of the page to find more: