Giant covalent structures

• What are giant covalent substances made of?

  Atoms joined together by covalent bonds
• How do diamond, graphite, and graphene differ?

  They have different structures and properties
• What is a covalent bond?

  A bond formed when atoms share electrons
• What is a molecule?

  A collection of two or more atoms held together by chemical bonds
• What is the smallest part of an element that can exist?

  An atom
• What distinguishes giant covalent substances from simple molecules?

  Giant covalent substances contain many atoms joined by covalent bonds
• What is silica an example of?

  A giant covalent substance
• What is the structure of silica?

  It contains many silicon and oxygen atoms joined by covalent bonds in a regular arrangement
• What is a covalent network?

  A giant regular arrangement of atoms held together by covalent bonds
• Why are giant covalent substances not classed as molecules?

  There is no set number of atoms joined together in their structure
• What do the atoms in a giant covalent compound represent?

  The ratio indicated by the chemical formula
• What are the melting and boiling points of giant covalent substances?

  They have very high melting and boiling points
• Why do giant covalent substances require a lot of energy to melt or boil?

  Because covalent bonds are strong
• Can giant covalent substances conduct electricity?

  Most cannot conduct electricity
• What is the exception among giant covalent substances that can conduct electricity?

  Graphite
• Why are giant covalent substances insoluble in water?

  They cannot form strong enough attractions with water molecules
• What does it mean for a substance to be insoluble?

  It cannot dissolve in a particular solvent
• Why do diamond and graphite have different properties?

  Because they have different structures
• What is a giant covalent substance?

  • Contains atoms joined by covalent bonds
  • Forms a giant network structure
  • Examples include diamond and graphite
• What is the structure of diamond?

  Diamond has a giant tetrahedral network structure
• What makes diamond the hardest known natural substance?

  The rigid network of carbon atoms held together by strong covalent bonds
• What is the melting point characteristic of diamond?

  Diamond has a very high melting point
• Why does diamond not conduct electricity?

  Because it has no free electrons
• What is the bonding structure of graphite?

  Each carbon atom in graphite is joined to three other carbon atoms
• What type of network structure do carbon atoms form in graphite?

  Graphite forms a hexagonal layered network structure
• What allows the layers in graphite to slide over each other?

  Weak forces between the layers
• What is unique about the outer electrons in graphite?

  Each carbon atom has one un-bonded outer electron
• What does it mean for electrons in graphite to be delocalised?

  Delocalised electrons are free to move through the structure
• Why is graphite useful for electrodes in batteries?

  Because it can conduct electricity due to delocalised electrons
• What property of graphite makes it useful as a lubricant?

  Its layers can slide over each other easily
• What are the properties and uses of diamond and graphite?

  Diamond:

  • Very hard
  • High melting point
  • Does not conduct electricity
  • Used for cutting tools

  
  

  Graphite:

  • Conducts electricity
  • Slippery due to weak forces between layers
  • Used for electrodes and lubricants
• What are giant covalent substances made of?


  Atoms joined together by bonds
• Why do diamond, graphite, and graphene have different properties?


  They have different structures
• What is graphene?


  A form of carbon consisting of a single layer of carbon atoms joined in hexagonal rings
• How does the structure of graphene compare to graphite?


  Graphene resembles a single layer of graphite
• What is the melting point of graphene?


  Very high
• Why is graphene considered strong?


  Due to its large regular arrangement of carbon atoms
• What allows graphene to conduct electricity well?


  It has delocalised electrons that can move freely
• What are fullerenes?


  Molecules of carbon with hollow shapes based on hexagonal rings
• What is a molecular form of carbon?

  A fullerene