Bonding, structure and properties

• What is ionic bonding?


  When a metal reacts with a non metal
• What happens in ionic bonding?

  Electrons are transferred from the metal to the non-metal, forming ions
• In ionic bonding, the metal becomes a positive ion but the non metal becomes a negative ion
• What is covalent bonding?

  When 2 non metals share a pair of electrons
• What is the saying for covalent bonding?

  Give to get
• Ionic compounds can only conduct electricity when molten or dissolved in solution
• Strong bonds between molecules can be found in ionic bonding
• In covalent bonding, there are weak bonds between molecules so are easily broken
• Covalent bonds have a low melting and boiling point
• How can crystals form?

  When ions in a compound are arranged in a giant ionic structure. Also known as a giant ionic lattice
• Ionic compounds have high melting and boiling points
• Ionic compounds cannot conduct electricity because their ions are held firmly in place
• Covalent bonds do not conduct electricity because there are no free electrons to carry the charge
• What is an allotrope?

  A different form of the same element.
• What are examples of allotropes of carbon?

  Diamond, graphite and graphene
• What are giant covalent structures?

  Lots of atoms joined together by covalent bonds
• What are properties of giant covalent structures?

  Very high melting points and variable electrical conductivity
• Diamond is the hardest natural substance due to it's rigid structure
• Diamond has a high melting and boiling point
• Diamond is shiny and strong
• What are some uses of diamond?

  Jewelry and drill tips
• Each carbon in diamond forms 4 covalent bonds
• Each carbon in graphite forms 3 covalent bonds
• The structure of graphite includes hexagonal layers
• Every carbon in graphite has 1 delocalised electron so it can conduct electricity
• Graphite is slippery because of the layers in it's structure
• Graphite is a good conductor of electricity because it's delocalised electrons can carry the electric charge
• Graphene can be used for making objects bulletproof e.g bulletproof vest
• Most metals are malleable and ductile
• What does malleable mean?


  The metal can be bent and shaped without it breaking
• What does ductile mean?

  Where most metals can be drawn into wires for electric cables
• Metallic bonds are strong so therefore have high melting and boiling points
• Metals are good conductors of heat and electricity because their delocalised electrons can move throughout the metal
• The greater the number of outer electrons a metal has, the higher it's melting and boiling point
• What is a nano particle?

  A particle of a substance that is 1-100nm in diameter
• Where is nano-silver used?

  Wound dressings to prevent infection, deodorants to kill bacteria, insides of fridges and socks
• How are nano particles of titanium dioxide used?

  In sunscreen to block UV rays to prevent sunburn and skin cancer
• What are the issues with nano-particles?


  Long term effects are unknown, they are so small they can pass through our skin and into our bloodstream, cause damage to environment and animals
• What are smart materials?

  Materials that have properties which mean that they can change reversibly depending on their environment
• What is thermochromic pigments?

  Pigments which can change colour reversibly with temperature