Abstract Boron lying in the second period and the third row of periodic table of the elements is a non-metal electron-defect element.It forms a series of covalent electron-defect compounds including boron hydrides,boron halide,boric acid and its salts.Structures of these electron-defect compounds and reasons for their stable existence are discussed.In addition,structures of diboron trioxide in gas,glassy and crystalline states (more detailed for α-B2O3) are introduced.
