Magnesium oxide
Molar mass: 40.30 g/mol · Class: Basic oxide
Elements: magnesium, oxygen
Structure
MgO forms an ionic lattice of Mg2+ and O2- ions in a cubic arrangement. The small, doubly charged ions attract each other very strongly, giving the compound its refractory properties.
Properties
White solid, melting point 2852 °C
Basic oxide: reacts with acids to form magnesium salts
Excellent electrical insulator at high temperature
Hygroscopic: slowly absorbs water and CO2 from air
Applications
Refractory lining for furnaces and kilns
Antacid and magnesium supplement (as directed)
Electrical insulation in heating elements
Low toxicity, but fine dust irritates eyes and the respiratory tract: wear a dust mask when handling powder. Follow supplement label doses; excess magnesium causes digestive upset.
Data source: IUPAC standard atomic weights 2021; molar mass computed from MgO