Fill-in-the blank.  Make sure to include the plus and negati…

Fill-in-the blank.  Make sure to include the plus and negative signs.  Do not write spaces.  (Example: If the answer is positive four enter +4 not + 4).  The sulfur atom in the sulfite ion, SO32-, has an oxidation number of .  The oxidation number of the number of bromine in Br2 is . The aluminum atom in aluminum hydride, AlH3, has an oxidation number of .