 By weight percent, the composition of scandium trihydride is 6.30% hydrogen and 93.70% scandium.In scandium trihydride, the formal oxidation states of hydrogen and scandium are -1 and +3 respectively, because of the electronegativity of scandium is lower than that of hydrogen.The stability of metal hydrides with the formula MH3 (M = Sc-Lu) increases as the atomic number of M increases.