Uranyl hydroxide
Uranyl hydroxide is a hydroxide of uranium with the chemical formula UO(OH) in the monomeric form and (UO)(OH) in the dimeric; both forms may exist in normal aqueous media. Uranyl hydroxide hydrate is precipitated as a colloidal yellowcake from oxidized uranium liquors near neutral pH.
Oxide
The oxide ion has the formula O. It is the conjugate base of the hydroxide ion, OH and is encountered in ionic solids such as calcium oxide. O is unstable in aqueous solution − its affinity for H is so great (p"K" ~ −38) that it abstracts a proton from a solvent HO molecule: