The ions Cr3 + and O2 - combine to form the ionic chromium oxide. in what proportions do these ions combine to produce a neutral compound?

When ions combine to form neutral compounds, their charges are usually crisscrossed to cancel out any net charge. For this example, Cr3 + and O2 - have different charges. Applying the crisscross method, the neutral compound is Cr2O3. This proportion balances out a net charge because two Cr3 + gives a + 6 charge, and three O2 - gives - 6 charge.