Aluminium, also known as aluminium, is an element of the periodic table and also a chemical compound. It is a metal largely used in industries and homes.
Formula and structure: The aluminium chemical formula is Al. The molar mass is 26.98g/mol. Metallic aluminium is found in its elemental form (elemental form is the most basic form, te one that is reflects on the periodic table) Al. The structure of the compound is analogue to a face-centered crystal system with an Al atom coordinates to six Al atoms, which allows the easy movement of the electron and thus, contributing with the conduction of the material. Its chemical structure can be written as below, in the common representations used for organic molecules.
Occurrence: Aluminium is found in the crust of Earth and in ores of bauxite around the world. It is the third of the most abundant elements in the crust's Earth. It is not found in isolated ways, but instead in combination with other elements forming different minerals such as cryolite, garnet, beryl. Aluminium is also found in the outer space as a component of other planets.
Preparation: Aluminium is mostly extracted from bauxite. Some processes to extract the Al from this mineral include the Bayer and the Hall-Héroult processes. In general, in the Bayer process the bauxite (aluminium oxide) is treated with sodium hydroxide and then, the compound formed reacts with several chemical agents to finally get the metallic aluminium.
Al2O3 + 2 NaOH → 2 NaAlO2 + H2O
2 NaAlO2 + 3 H2O + CO2 → 2 Al(OH)3 + Na2CO3
For the Hall, Héroult process, the oxide-reduction reaction ends by forming CO2 and Al:
2 Al2O3 + 3 C → 4 Al + 3 CO2
Physical properties: Aluminium is a silver-white, ductil metal. Its density is 2.70 g/mL and the melting point is 660 °C, the boiling point is 2470 °C.
Chemical properties : Aluminium can form several compounds through different reactions. It is well known for losing three electrons to form cation aluminium Al3+ that can react with different anions to form salts. In fact, the most common form of the aluminium in Earth is a cation combined with oxygen to form the aluminium oxide Al2O3.
Uses: Aluminium is largely used as a metal to produce a huge amount of products. It is used for example to produce mechanical pieces, automotive industry components, beverage cans, house equipment and together with other metals as zinc and copper forms alloys that are also extensively used. In chemical synthesis, it can be used as a catalyst.
Health effects / safety hazards: Most authors highlight that aluminium is non-toxic for human health. However, it is toxic for aquatic live and for soils. Aluminium is not flammable.