6.4 The Structure of Metals

What will we learn? What makes metals different? What properties do metals have and why? What are alloys and how are they important?

Metallic Bonds Metals are elements that are good conductors of heat and electricity This ability comes from how metals bond with one another Metals both lose and gain electrons

Metallic bonds… Metallic bonds – the attraction between a metal cation and the shared electrons that surround it The metal atoms make a lattice that is held in place by the cations and surrounding electrons

An Analogy Think of the tables in the lunchroom Adults are sitting at the tables, eating and chatting Kids are running around the tables, playing

The Analogy continued… The parents represent the metal cations, the children the electrons The children are free to roam, but stay somewhat close to the parents

The Reason for Properties Conductivity comes from the ability of the electrons to move Malleability comes from the lattice structure being the same – If the metal is hit, the cations just shift to another’s position

What are Alloys? An alloy is a mixture of two or more metals For example, gold is sold by karat – 24 karat is 100% gold – 12 karat is 50% gold, 50% something else

Copper Alloys Bronze – a mixture of copper and tin – Both are soft, but together they are harder Brass – a mixture of copper and zinc

Iron Alloys Steel – mixture of iron and carbon Stainless steel – iron, carbon, and chromium Extra elements fit into the iron lattice, making it stronger

Other Alloys Aluminum and other metals like copper and manganese make lightweight, but strong frames Aluminum and magnesium alloys are good for aircraft parts, light but strong