Substances with many covalent bonds

• What are giant covalent substances made of?

  Many atoms joined together by covalent bonds
• Name three forms of carbon that have giant covalent structures.

  Diamond, graphite, and graphene
• What is a covalent bond?

  A bond formed when atoms share electrons to achieve a full outer shell
• What is the difference between small molecules and giant covalent substances?

  Small molecules contain a fixed number of atoms, while giant covalent substances contain many atoms
• What is silicon dioxide commonly called?

  Silica
• What is the structure of silicon dioxide?

  It has a giant covalent structure with many silicon and oxygen atoms
• Why do substances with giant covalent structures have high melting and boiling points?

  Because large amounts of energy are needed to overcome their strong covalent bonds
• What state are substances with giant covalent structures typically in at room temperature?

  Solids
• What is the definition of melting point?

  The temperature at which a solid changes into a liquid as it is heated
• What is the definition of boiling point?

  The temperature at which a substance rapidly changes from a liquid to a gas
• Why do most substances with giant covalent structures not conduct electricity?

  Because they have no charged particles that are free to move
• Which form of carbon can conduct electricity?

  Graphite
• What are the typical properties of substances with giant covalent structures?

  • High boiling points
  • High melting points
  • Cannot conduct electricity (except graphite)
• What is the main compound found in sand?

  Silicon dioxide
• How does the arrangement of atoms in a giant covalent structure differ from that in small molecules?

  Atoms in giant covalent structures are linked in a regular arrangement, while small molecules have a fixed number of atoms
• What is meant by the term 'giant covalent structure'?

  A structure in which very large numbers of atoms are joined together by covalent bonds in a regular network
• What is the energy required to overcome strong covalent bonds measured in?

  Joules (J)
• What happens to the atoms in a giant covalent structure when it is heated?

  The atoms remain linked but vibrate more vigorously as energy is added
• How does the presence of charged particles affect the conductivity of a substance?

  Substances with free charged particles can conduct electricity, while those without cannot