Elements: occurrence and extraction

The decreasing electropositive character of the elements beyond the series is displayed in the typical minerals they create, and in the methods needed to extract them. Early elements are observe in oxide or complex oxide minerals (example TiO₂, CrFeO₃) and are termed as lithophilic, where later elements are found mostly in sulfides (example NiS) and are called chalcophilic. Iron forms the dividing line in this tendency, and is notice both like Fe₂O₃ and FeS₂.

Reduction of later elements is comparatively easy, as sulfides might be roasted to create oxides and then reduced with carbon.For instance, iron, a main structural metal, is created in blast furnaces through reduction of Fe₂O₃:

2Fe₂O₃ + 3C→4Fe + 3CO₂

Though, early transition metal oxides cannot be reduced by this way, since they form stable carbides (example TiC) and/ or since the temperature needed for reduction through carbon is very high. The Kroll process for make of Ti involves first making TiCl₄,

TiO₂  +  2CI₂ + 4C →  TiCI₄  + 4CO

That is then reduced through metallic magnesium. Titanium is extensively used as a lightweight structural metal; even though potentially extremely reactive towards water and air it forms an extremely inert protective TiO₂ film.