CHM Ch4 - Metallic bonding

Properties of metals (6)

• High melting and boiling points

• Conduct electricity well

• Conduct heat well

• High densities

• Malleable and ductile

• Lustrous

Metals are hard and have high melting and boiling points (what does this tell us about structure?)

Strong electrostatic forces between the cations and sea of delocalised electrons make metallic bonds very hard to break

Conduct electricity well (what does this tell us about structure?)

Delocalised electrons are free to move around the metal lattice

Conduct heat well (what does this tell us about structure?)

Delocalised electrons are free to move and collide into other particles to transfer heat energy throughout the metal

High densities (what does this tell us about structure?)

Atoms are closely packed together due to strong bonds

Malleable and ductile (what does this tell us about structure?)

Strong bonds allow layers of cations to slide over each other while still being bonded by delocalised electrons

Lustrous

Free electrons are present, allowing the metal to reflect light and appear shiny

Metallic bonding model (3 parts of the theory)

1. Metal atoms lose their valence electrons to become cations

2. These cations are arranged in a tightly packed lattice

3. Free valence electrons move in between cations as a sea of delocalised electrons

Metal + Water

Metal + Water → Metal hydroxide + Hydrogen gas

Metal + Oxygen

Metal + Oxygen → Metal oxide

Metal + Acid

Metal + Acid → Salt + Hydrogen gas

Ore

A rock that contains enough metal for it to be mined profitably. The metal is not pure, but rather in compounds with other elements.

Linear economy

Materials ultimately become waste

Circular economy

Products are made to be collected, recycled and reused to minimise negative impacts on the environment

Why should metals be recycled in a circular economy?

• They can be re-melted and re-shaped relatively easily

• Energy required to recycle metals is less than that required to extract them

• Recycling metals releases less CO2 emissions than mining