A shared pair of electrons
The covalent bond.
A hydrogen atom wants one more
A hydrogen atom has one electron in its K-shell. The K-shell can hold 2 electrons in all.
What could two hydrogen atoms do so that each ends up with a complete K-shell?
What this lesson covers
The idea
A covalent bond is the interaction between atoms through a shared pair of electrons, which attracts both nuclei and holds the atoms together as a stable molecule.
A hydrogen atom wants one more
A hydrogen atom has one electron in its K-shell. The K-shell can hold 2 electrons in all.
What could two hydrogen atoms do so that each ends up with a complete K-shell?
- Share their electrons
- One gives up its electron to the other
- Nothing, since one electron is enough
Two hydrogen atoms meet
Press Next step to watch the hydrogen molecule form.
The covalent bond
The shared pair belongs to both atoms. It pulls on both nuclei at once, and that holds the two atoms together as a stable molecule.
A covalent bond is the interaction between atoms through a shared pair of electrons, which attracts both nuclei and holds the atoms together as a stable molecule.
Notes
A covalent bond is formed when atoms share a pair of electrons. The pair attracts both nuclei and holds the atoms as a stable molecule.
Check yourself
What is a covalent bond?
How many electrons are there in the shared pair that forms the bond in a hydrogen molecule, H₂?
Answer: 2
Each hydrogen atom contributes one electron, so the shared pair has 2 electrons.
Why does a hydrogen atom need one more electron?
What does the shared pair of electrons do?
- An interaction between atoms through the transfer of an electron. In a covalent bond the electrons are shared, not handed over.
- An interaction between atoms through a shared pair of electrons — correct. Yes!
- A force between a nucleus and its own electrons only. A covalent bond is between atoms, through a shared pair that attracts both nuclei.
- The K-shell can hold 8 electrons. The K-shell holds 2 electrons in all. 8 is the octet of a shell that is not the K-shell.
- It has no electrons at all. A hydrogen atom has one electron in its K-shell.
- The K-shell can hold 2 electrons and the atom has only 1 — correct. Yes!
- It attracts both nuclei and holds the atoms together — correct. Yes!
- It pushes the two nuclei away from each other. The shared pair attracts both nuclei, and that holds the atoms together.
- It attracts only one of the two nuclei. The shared pair attracts both nuclei.