Covalent bond
Atoms that share a pair of electrons.
Two lonely atoms
A hydrogen atom has one electron in its K shell and needs one more to fill it. Two hydrogen atoms come close together.
How can both atoms fill their K shell?
What this lesson covers
The idea
A bond formed by the sharing of an electron pair between two atoms is a covalent bond; the shared electrons belong to the outermost shells of both atoms, so both attain noble gas configuration.
Two lonely atoms
A hydrogen atom has one electron in its K shell and needs one more to fill it. Two hydrogen atoms come close together.
How can both atoms fill their K shell?
- One atom hands its electron over to the other
- The two atoms share their electrons as a pair
- The atoms stay apart and nothing changes
Sharing a pair
Press Next step. Blue dots are electrons of one atom and red crosses are electrons of the other.
Both atoms count the pair
In each picture the shared pair is counted by both atoms. That is how both atoms get a full outer shell without any atom losing or gaining an electron.
A bond formed by the sharing of an electron pair between two atoms is a covalent bond. The shared electrons belong to the outermost shells of both atoms, so both atoms attain noble gas configuration.
Notes
A bond formed by sharing an electron pair between two atoms is a covalent bond. The shared electrons belong to the outermost shells of both atoms, so both attain noble gas configuration.
Check yourself
In H₂, how many electrons does each hydrogen atom count in its K shell after the pair is shared?
Answer: 2
Each atom counts the shared pair, so each has 2 electrons, like helium.
Which describes a covalent bond?
To which atoms do the shared electrons belong?
By sharing a pair, a hydrogen atom attains the configuration of which noble gas?
- A bond formed when one atom takes electrons from another. Gaining and losing electrons is how ionic compounds form. In a covalent bond the electrons are shared.
- A bond formed by sharing an electron pair between two atoms — correct. Yes!
- A force of attraction between one molecule and the next. That is an inter-molecular force. A covalent bond holds atoms together inside a molecule.
- Only to the atom that has more protons. The shared pair belongs to the outermost shells of both atoms, not to just one of them.
- To the inner shell of one atom. The shared electrons belong to the outermost shells of both atoms.
- To the outermost shells of both atoms — correct. Yes!
- Helium — correct. Yes!
- Neon. Neon has a full outer shell of eight electrons. Hydrogen's nearest noble gas is helium, which has two electrons in its K shell.
- Argon. Argon has a full outer shell of eight electrons. Hydrogen's nearest noble gas is helium, with two electrons in its K shell.