Be careful to measure accurately when you are drawing a 2D shape. Draw a 2D shape that has 4 equal sides that are each 3 cm long and has 4 right angles. What is this shape called? It is a square.

Very hard. Diamond has strong covalent bonds arranged in a rigid tetrahedral structure. Diamond is used in cutting tools for drilling through hard materials like rock and glass. High melting ...

It’s a kind of trick that people have been trying to do for 3,000 years, though they never succeeded in solving the geometry of making a structure of this kind scale in three dimensions. There are ...

Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 532 10 Pardubice, Czech Republic ...

Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K.