Acid-Base Properties of Period 3 Oxides This investigation explores how the acid-base character of oxides formed by Period 3 elements evolves across the period—from sodium to sulfur. As predicted by periodic trends, the chemical behavior of these oxides in water reflects a transition from basic to acidic properties. The hypothesis proposes that sodium and magnesium oxides will yield alkaline solutions, aluminum oxide will exhibit amphoteric behavior, and the oxides of silicon, phosphorus, and sulfur will produce acidic solutions. This progression is attributed to increasing electronegativity and a shift from ionic to covalent bonding across the period. To test this, each oxide was reacted with water and, where insoluble, with both acid and base to assess amphoteric or acidic behavior. pH measurements and qualitative observations were recorded to determine the nature of each oxide. The experiment was carefully controlled for mass, volume, and temperature, with safety precautions in place due to the reactive and corrosive nature of certain oxides. The results are expected to reinforce the hypothesis and illustrate the link between atomic structure, bonding type, and acid-base behavior—highlighting the predictive power of periodicity in chemical properties.