Get tutored by the creator of Mooramo

As well as making Mooramo, I also tutor Science and Maths in London and online.

To find out more, visit my website, georgewellertutoring.co.uk

How Covalent Bonding Affects the Outer Shell

When two atoms form a covalent bond, they usually each contribute one electron to form a shared pair of electrons. This pair of electrons is now in the outer shells of both atoms. This means that the number of electrons in each atom's outer shell increases by 1.

For example, the diagram below shows two fluorine atoms before and after forming a single covalent bond. Before bonding, they each have 7 electrons in their outer shell. After bonding they each have 8 electrons in their outer shell. By sharing, they both increase the number of electrons in their outer shell without any new electrons actually being added to the system.

Diagram of two florine atoms forming a covalent bond. At the top, two separate fluorine atoms are shown next to each other. They each have seven electrons in their outer shell. Below, the two atoms are shown joined together by a single covalent bond. They each now have eight electrons in their outer shell.

Two fluorine atoms forming a single covalent bond. They go from each having 7 electrons in their outer shell to each having 8 electrons in their outer shell.

When two atoms form a double bond, the number of electrons in each atom's outer shell increases by 2. For example, if two oxygen atoms form a double bond, they each go from having 6 electrons in their outer shell to having 8 electrons in their outer shell.

Diagram of two oxygen atoms forming a double bond. The two separate atoms are shown at the top, each with 6 outer shell electrons. The bonded atoms are shown below, each with 8 outer shell electrons (due to the fact that they each gain one electron from each shared pair, and they are sharing two pairs).

Two oxygen atoms forming a double covalent bond. They go from each having 6 electrons in their outer shell to each having 8 electrons in their outer shell.

When two atoms form a triple bond, the number of electrons in each atom's outer shell increases by 3. For example, if two nitrogen atoms form a triple bond, they each go from having 5 electrons in their outer shell to having 8 electrons in their outer shell.

Diagram of two nitrogen atoms forming a triple bond. The two separate atoms are shown at the top, each with 5 outer shell electrons. The bonded atoms are shown below, each with 8 outer shell electrons (due to the fact that they each gain one electron from each shared pair, and they are sharing three pairs).

Two nitrogen atoms forming a triple covalent bond. They go from each having 5 electrons in their outer shell to each having 8 electrons in their outer shell.

One atom can covalently bond to multiple other atoms. This means that an atom can increase the number of electrons in its outer shell by various different amounts by forming different combinations of single, double and triple bonds. For example, if an atom forms two single bonds and one double bond, the number of electrons in its outer shell will increase by 4.

Flashcards

Flashcards help you memorise information quickly. Copy each question onto its own flashcard and then write the answer on the other side. Testing yourself on these regularly will enable you to learn much more quickly than just reading and making notes.

1/3

What happens to the number of electrons in an atom's outer shell when it forms a single covalent bond?

2/3

What happens to the number of electrons in an atom's outer shell when it forms a double covalent bond?

3/3

What happens to the number of electrons in an atom's outer shell when it forms a triple covalent bond?

Donate

Please consider donating to support Mooramo. I am one person doing this whole project on my own - including building the site, writing the content, creating illustrations and making revision resources. By making a one-time or repeating donation you will buy me time to work on Mooramo, meaning that I can get new content on here more quickly.

Donate