3.3.1 - metal structure, bonding and properties Flashcards
what 2 components does a structure of a metal have?
- a lattice if positive metal ions
- a ‘sea’ of delocalised electrons
what is metallic bonding?
the electrostatic attraction between the positive metal ions and the negative delocalised electrons
properties of metals:
- high melting point
- conduct electricity
- malleable
why do metals have high melting points
- metallic bonding is very strong
- lots of energy is needed to break it
why do metals conduct electricity
delocalised electrons are free to move through the lattice
why are metals malleable
the layers of metal ions can slide over each other
what are alloys
mixtures of a metal with one or more other elements
why are alloys harder than pure metal
the different sized atoms/ions prevent the layers of metal ions from sliding over each other
-> this means the alloy is less malleable
use of iron and reason
- making steel
- steel is more useful than iron
use of low-carbon steel and reason
- ships, cars, bridges
- strong, but low-carbon so can be hammered into various shapes
use of high-carbon steel and reason
- tools .e.g. knives, screwdrivers
- high-carbon so less malleable and stiffer than low-carbon steel
use of stainless steel and reason
- cutlery, cooking utensils, kitchen sinks
- Cr forms an oxides layer that resists corrosion, so stays shiny and clean
use of copper and reason
- wires, cooking pans, water pipes
- excellent conductor of electricity + heat, unreactive and malleable
use of aluminium and reason
- aircraft bodies, power cables
- low-density and high strengths, low-density and conducts
