Section 1h: metallic crystals
1.46 describe a metal as a giant structure of positive ions surrounded by a sea of delocalised
electrons
1.47 explain the malleability and electrical conductivity of a metal in terms of its structure and bonding
Metallic crystals have a giant structure of positive ions surrounded by a ‘sea’ of delocalised electrons
which can move around in the lattice as shown below. The bond between the metal ions is called a
metallic bond. A metallic bond is the attraction between the positive metal ions and the delocalized
electrons.
(from http://www.bbc.co.uk/scotland/learning/bitesize/higher/chemistry/energy/bsp_rev3.shtml on 15/6/2010)
This structure and bonding allows the following properties as shown by the table below.
Property
Explanation
Metals are ductile (=can be pulled into
wires) and malleable (= can be bent or
hammered into different shapes without
breaking);
.
The layers of positive metal ions can slide past each
other without breaking the metallic bond; this is the case
because there will always be delocalised electrons
between these positive metal ions even when they
change their positions. There will always be a force of
attraction i.e. the metallic bonds to hold the metal ions
together.
Metals conduct electricity and heat well.
Sea of delocalised electrons can move through the
lattice and carry the negative charge through lattice.
Section 1g metallic crystals
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