flashcards & answering structures

• what is metal lattice structure

  metal lattice is a lattice of positive metal ions surrounded by sea of delocalized electrons
• why do metals and alloys have high melting and boiling point?

  except for group 1 metals,metals and alloys have a metallic lattice structure. it has strong electrostatic forces of attraction between the positive metal ions and sea of delocalized electrons. more energy is needed to overcome these forces hence it have high melting and boiling point
• what does it mean to be malleable?

  able to be bent into sheets
• what does it mean to be ductile?

  can be made into wires
• why are metals and alloys able to conduct heat and electricity?

  delocalized electrons are able to move to transfer heat and carry electric current to conduct electricity
• what is bronze alloy made of?

  copper and tin
• what is brass alloy made of?

  copper and zinc
• what is solder made of?

  tin and lead
• what is rose gold made of?

  copper and gold
• what is purple gold made of?

  aluminum and gold
• what is steel made of?

  iron and carbon
• what is stainless steel made of?

  iron, carbon, chromium and nickel
• what is the purpose and example of brass and bronze?

  to increase hardness and strength

  ship's bell
• what is the purpose and example of solder?

  to lower melting point

  circuit board
• what is the purpose and example of rose gold and purple gold?

  to improve appearance or create new colours

  jewellery
• what is the purpose and example of steel?

  to increase hardness

  warehouse shelves
• what is the purpose and example of stainless steel?

  to increase resistance to corrosion

  surgical equipment
• explain why pure metal is soft

  pure metal is made up of atoms of the same size that are very closely packed regularly in layers. layers of atoms can slide over one another easily when a force is applied hence pure metals are soft
• explain why alloy is hard

  alloy is made up of atoms of different sizes , disrupting orderly arrangement. layers of atoms cannot slide over on another when a force is applied hence alloys are harder and stronger than pure metals
• what does sodium chloride and acid do in a rusting experiment?

  acts as a catalyst, increasing the formation of rust on the iron, accelerating the rusting process
• what does oil do in a rusting experiment?

  act as a barrier to prevent water and oxygen from coming into contact with iron
• what does boiled water do in a rusting experiment?

  removes dissolved oxygen, allowing the set up to not contain oxygen
• what does drying agent (sodium chloride) do in a rusting experiment?

  absorbs water vapour
• what is some methods for rust prevention

  coating with paint/grease/plastic

  galvanizing, coating the metal with zinc

  attach a more reactive metal
• how does sacrificial protection prevents rusting?

  magnesium/zinc being more reactive will corrode in place of iron hence preventing rust from forming on iron
• ionic equation for rusting of iron

  Fe(s) -> Fe3+(s)+3e-
• ionic equation for sacrificial protection using magnesium

  Mg(s)->Mg2+(s)+2e-
• ionic equation for sacrificial protection using zinc

  Zn(s)->Zn2+(s)+2e-