Properties and Structure of Materials - Metals Flashcards
List some of the properties of metals.
- High boiling points
- Good conductors of electricity and heat
- High densities
- Malleable
- Ductile
- Lustrous/reflective
- Hard with high tensile strength
- Low ionisation energies
List some of the properties of transition metals.
- Harder than metals
- Higher densities
- Higher melting points
- Strong magnetic properties
What is the metallic bonding model?
Metallic bonding is the electrostatic force of attraction between a lattice of positive ions and delocalised valence electrons.
The lattice of cations is surrounded by a ‘sea’ of freed delocalised electrons. This is what makes it a good conductor of electricity.
What are the limitations of the metallic bonding model?
- range of melting points, hardness and densities of different metals.
- differences in electrical conductivities of metals
- magnetic nature of metals such as cobalt, iron and nickel.
How does the metallic bonding model explain why metals are hard and have relatively high boiling points?
Strong electrostatic forces of attraction between positive metal ions and the sea of delocalised electrons hold the metallic lattice together.
How does the metallic bonding model explain why metals are good conductors of electricity?
Free moving delocalised electrons will move towards a positive electrode and away from a negative electrode in an electric circuit.
How does the metallic bonding model explain why metals are malleable and ductile?
When a force causes metal ions to move past each other, layers of ions are still held together by the delocalised electrons between them.
Metals are usually hard and tend to have high boiling points what does this tell us about the structure?
The forces between the particles must be strong.
Metals conduct electricity in the solid state and in the molten (melted) liquid state what does this tell us about the structure?
Metals have charged particles that are free to move.
Metals are malleable and ductile what does this tell us about the structure?
The attractive forces between the particles must be stronger than the repulsive forces between the particles when the layers of particles are moved.
Metals generally have high densities what does this tell us about the structure?
The particles are closely packed in a metal.
Metals are good conductors of heat what does this tell us about the structure?
There must be a way of quickly transferring energy throughout a metal object.
Metals are lustrous or reflective what does this tell us about the structure?
Free electrons are present, so metals can reflect light and appear shiny.
Metals tend to react by losing electrons what does this tell us about the structure?
Electrons must be relatively easily removed from metal atoms.
What are the different ways metals can be modified?
- through alloy production
- by heat treatment
- by the formation of nano-sized structures
