METALS

METALS

1. NON-METALS - chalk, stone, sand, coal, diamonds

   • All have different properties and some properties that are similar. A property tells us what the material is like.
   • Ceramics - pottery and clay (fire in kiln), glass, porcelain. Polymers (human-made plastics/fibres) - rubber, nylon, wood, cotton, fabric.
     • hard
     • dull
     • strong
       • Wood so long as the load is at right angles to the wood fibres. If the load (or force) is in the same direction, the wood can split.
       • concrete is strong when load pushes downwards. Pulling forces can break it
         • concrete beam has reinforcing rod (reinforced concrete) in lower part where the pulling forces act.
       • Plastic is strong until heated and melts (becomes weak)
       • Plaster of Paris used to set broken bones
       • Use straw to reinforce clay bricks
     • brittle
       • glass and ceramics
     • Poor conductors of heat
   • PROCESSING MATERIALS
     • COMBINE = PUTTINGTWO OR MORE SUBSTANCES TOGETHER (A COMBINATION) TO PRODUCE A NEW MATERIAL.
       • Flour and water form glue-like paste
       • flour, oil and water form modelling clay
     • PROCESS RAW MATERIALS TO PRODUCE MANUFACTURED MATERIALS. PROCESSING=A SERIES OF ACTIONS THAT YOU CAN CARRY OUT WITH A SPECIFIC AIM
       • concrete
         • starting materials = sand, gravel, cement, water
         • slabs, beams, blocks
       • heat sand to form glass
       • Polyfilla is used to fill holes and cracks in walls

2. gold, brass, silver, iron, copper, lead, aluminium, tin

   • shiny
   • hard
   • malleable - can be hammered into shapes when heated
   • ductile - when heated can be pulled to form thin wires without breaking
   • Occur naturally in ore (rock)
     • Mine from Earth.
       • Gold mines - Gauteng, Free State
       • Copper and iron mines - Northern Cape
       • Chrome and platinum mines in Limpopo and North West
   • good conductors of heat (heat energy travels through them easily)
     • useful for pans and pots as can cook food
     • not useful for pot handles (use wood/plastic)
   • some are magnetic=material attracted to them - iron, steel
     • some are not magnetic - nickel, copper
     • drives hairdryers, trains, produces sound for television sets and radios, computers use to store information, homing pigeons use Earth's magnetism to sense direction
   • Iron rusts and some metals tarnish or become dull
   • strong=will not break easily with the force of a load
   • melt at high temperatures
     • solid - can be heated at high temperature to form liquid. When cooled, forms solid. Iron melts at highest temperature, lead melts at lowest temperature (copper melts at higher temperature so can melt lead in copper spoon)