When lithium metal is burned in dry air, the product is a fine white powder of lithium oxide, . The 2:1 ratio of atoms is inevitable because each oxygen atom must acquire two electrons to complete its neon shell, but each lithium atom has only one outer electron to give. The powder actually is made of microcrystals of and ions in a salt. dissolves in water to produce hydrated ions and hydroxide ions, so is a basic oxide:




The important factor in this reaction is the oxide ion, (see right). It has such a strong attraction for protons that it can take one away from a water molecule, thereby creating two hydroxide ions:



This reaction should remind you of the way that ammonia molecules produce hydroxide ions by pulling water molecules apart: