Oxygen atomThe single large atom. Both hydrogen atoms are bonded to it.
Hydrogen atomOne of the two small atoms. Each is bonded to the oxygen.
Covalent bondA shared pair of electrons that holds two atoms together.
Partial negative chargeThe oxygen side of the molecule is slightly negative.
Partial positive chargeEach hydrogen atom is slightly positive.
Together 2
Hydrogen bondA weak pull from a hydrogen atom to another molecule's oxygen.
Water moleculeTwo hydrogen atoms bonded to one oxygen atom.
Electrons 2
Shared pair of electronsTwo electrons held by both atoms. Each shared pair is one covalent bond.
Lone pairTwo electrons that belong to the oxygen alone. It has two such pairs.
How this list was compiled: Every name and fact checked on 2026-10-01 and read again on 2026-10-02, a name kept only where two independent sources use it. (1) U.S. Geological Survey, Water Science School (public domain): Adhesion and Cohesion of Water, https://www.usgs.gov/special-topics/water-science-school/science/adhesion-and-cohesion-water , and Water, the Universal Solvent, https://www.usgs.gov/special-topics/water-science-school/science/water-universal-solvent (two hydrogen atoms on one side of an oxygen atom; a covalent bond; the oxygen side has a partial negative charge and the hydrogen side a partial positive charge; the positive side of one molecule attracts the negative side of another; hydrogen bonds drawn as dotted lines). (2) CK-12 Foundation through LibreTexts Chemistry, Introductory Chemistry 15.1 Structure of Water, https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/15%3A_Water/15.01%3A_Structure_of_Water ; 9.6 Single Covalent Bonds, https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/09%3A_Covalent_Bonding/9.06%3A_Single_Covalent_Bonds ; 9.19 Hydrogen Bonding, https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/09%3A_Covalent_Bonding/9.19%3A_Hydrogen_Bonding (oxygen pulls harder on the electrons shared in the covalent bonds; partial negative and partial positive charge, written with delta; bent because of the two lone pairs; a shared pair of electrons; a lone pair is not shared between atoms; the oxygen of water has two bonding pairs and two lone pairs; a hydrogen bond runs from the hydrogen atom of one molecule to a lone pair on the oxygen of a neighbor and is far weaker than a covalent bond). (3) Wikipedia, text only: Properties of water, https://en.wikipedia.org/wiki/Properties_of_water ; Covalent bond, https://en.wikipedia.org/wiki/Covalent_bond ; Lone pair, https://en.wikipedia.org/wiki/Lone_pair ; Hydrogen bond, https://en.wikipedia.org/wiki/Hydrogen_bond ; Chemical polarity, https://en.wikipedia.org/wiki/Chemical_polarity (two hydrogen atoms covalently bonded to one oxygen atom; shared pairs or bonding pairs; a lone pair is also called an unshared pair; two lone pairs on the oxygen; the oxygen partly negative and each hydrogen partly positive, written delta minus and delta plus; a bent, not linear, molecule; up to four hydrogen bonds per molecule, two taken on the lone pairs and two given by the hydrogen atoms; hydrogen bonds weaker than covalent bonds). (4) Chemguide, Intermolecular bonding: hydrogen bonds, https://www.chemguide.co.uk/atoms/bonding/hbond.html (each water molecule can form four hydrogen bonds, one on each lone pair and one through each hydrogen atom; a hydrogen bond is far weaker than a covalent bond). Licence: own work
The drawing: Drawn for this site on 2026-10-01 from plain geometry; nothing traced. Licence: own work
How it works
A water molecule is one oxygen atom joined to two hydrogen atoms, set at an angle. The names are on the drawing. Two more views show five molecules together, then the electron pairs.
Read the full guide
Inside one molecule
Each stick is a covalent bond: a pair of electrons shared by the oxygen atom and a hydrogen atom. Oxygen pulls the shared electrons closer, so its side has a partial negative charge and each hydrogen a partial positive charge. The oxygen also holds two lone pairs, which give the molecule its bent shape.
Between molecules
A hydrogen bond is the pull between one water molecule's hydrogen atom and the oxygen atom of another, drawn as a dotted line. The middle molecule has four: two reach its oxygen, and one leaves each of its hydrogen atoms.
The small curly sign on each badge is the Greek letter delta. Delta plus and delta minus mean a partial charge, not a whole one.
Questions and answers
What are the parts of a water molecule?
One oxygen atom and two hydrogen atoms, joined by two covalent bonds. The oxygen atom also carries two lone pairs of electrons. The formula is H2O.
Why is a water molecule polar?
The oxygen atom attracts the shared electrons more strongly than the hydrogen atoms do, and the molecule is bent. So the oxygen side is partly negative and the hydrogen side partly positive.
What is the difference between a covalent bond and a hydrogen bond?
In water, a covalent bond holds the atoms of one molecule together by sharing a pair of electrons. A hydrogen bond is a much weaker attraction between two molecules: a hydrogen atom of one and the oxygen atom of the other.
How many hydrogen bonds can one water molecule form?
Up to four. Its oxygen atom can take two, one on each lone pair, and each of its two hydrogen atoms can make one with the oxygen atom of another molecule.
Is a water molecule straight or bent?
Bent. The oxygen atom's two lone pairs push the two bonds toward each other, so the three atoms do not lie in a straight line.