Magnesium oxide Magnesium oxide Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of and consists of a lattice of Mg ions and O ions held together by ionic bonding. Magnesium hydroxide forms in the presence of water (MgO + HO → Mg(OH)), but it can be reversed by heating it to separate moisture. Magnesium oxide was historically known as magnesia alba (literally, the white mineral from magnesia – other sources give magnesia alba as MgCO), to differentiate it from "magnesia
U Should've Known Better song entered the "Billboard" Hot 100 chart, where it debuted at number 67 in the week of June 6, 2004, the second-highest debut of the week. "U Should've Known Better" remained twenty weeks on the chart, reaching its peak position of number 19 in its ninth week. It marked the second single from "After the Storm" to reach the top twenty on the Hot 100chart and, as the album's final single, would remain its second highest-charting offering behind leading single "So Gone." Although never released on a CD single or CD maxi single format, "U Should've Known Better" was also