Lewis structure of H₃O⁺
8 valence electrons. Three O-H single bonds, with one lone pair on O.
Lewis structure
8 valence electronsFormal charges: O +1
Why this shape
- O has 6 valence electrons. In the Lewis structure it makes three single bonds to H and keeps one lone pair, which leaves it a formal charge of +1.
- Steric number = three sigma bonds + one lone pair = 4, so O is sp³ hybridised.
- Four electron pairs point to the corners of a tetrahedron (tetrahedral electron geometry). With one lone pair in place of atoms, the atoms make a trigonal pyramidal shape.
- Repulsion falls in the order lone pair to lone pair > lone pair to bond pair > bond pair to bond pair. The lone pair pushes the bond pairs closer, so the angle is less than 109.5°, less than the ideal 109.5°.
- H₃O⁺ is an ion with an overall charge of +1, so it is not described as polar or non-polar.
How to draw it
- Count the valence electrons: O 6 + 3 × H 1 − 1 for the ⁺ charge = 8 valence electrons, 4 pairs.
- Put O in the middle and join it to the three outer atoms with single bonds.
- Give each outer atom lone pairs until it has an octet (H needs only two electrons), then put any electrons left over on the central atom.
- Result: three O-H single bonds, with one lone pair on O.
- Formal charge = valence electrons − lone pair electrons − number of bonds. Here: O +1.
Class 11, Chapter 4 Chemical Bonding and Molecular Structure.
Lewis structure of H3O+: quick answers
How many valence electrons are in H3O+?
O 6 + 3 × H 1 − 1 for the ⁺ charge = 8 valence electrons, 4 pairs.
What are the formal charges in the Lewis structure of H3O+?
O +1; every other atom is zero. Formal charge = valence electrons - lone pair electrons - number of bonds.
How many lone pairs are in the Lewis structure of H3O+?
1 in all, 1 of them on the central O.