Diamond + Silicon dioxide

• Giant covalent molecules are always solids at room temperature.
• They are always solids due to their very high melting and boiling points
• Giant covalent molecules (diamond, silicon dioxide and graphite) have millions of covalent bonds and to melt/boil these molecules, we need to break each of these bonds. This takes vast amounts of energy!
• Diamond is formed from the element carbon
• Diamond has a very high melting/boiling point, is very strong and cannot conduct electricity
• Why can't diamond conduct electricity?

  All of the outer electrons are in covalent bonds, therefore diamond has no free electrons to carry electrical charge?
• Silicon dioxide (often called silica) is the main compound found in sand. It is an example of a substance with a giant covalent structure. It contains many silicon and oxygen atoms. All the atoms in its structure are linked to each other by strong covalent bonds. The atoms are joined to each other in a regular arrangement, forming a giant covalent structure. There is no set number of atoms joined together in this type of structure.