What is the molecular shape of the isolated hydronium ion, H₃O⁺, formed when water accepts a proton?

Explanation

The isolated hydronium ion, H₃O⁺, has three O–H bonds and one lone pair on its central oxygen. Its four electron domains have an approximately tetrahedral arrangement, while the arrangement of the three hydrogen atoms around oxygen is trigonal pyramidal. Electron-domain geometry and molecular shape are different descriptions.