Metallic Structures

Essentials

Metallic structures refer to the arrangement of atoms in a piece of metal. These atoms organise themselves in a closely packed, regularly repeating pattern, forming a metallic lattice.
Within the lattice, valence electrons from the metal atoms dissociate from their parent atoms to form a ‘sea’ of delocalised electrons. This phenomenon is known as metallic bonding.
These delocalised electrons are free to move throughout the structure, contributing to many of the properties unique to metals.
Among metals, the type of structure (body-centred cubic, face-centred cubic, or hexagonal close-packed) can vary, depending upon the way the atoms are arranged.

Properties of Metallic Structures

Generally, metals have high melting and boiling points due to the strong metallic bonds that hold the atoms together.
Metals often have great tensile strength and are highly malleable and ductile, meaning they can be bent, hammered or drawn into thin wires without breaking.
Thanks to the delocalised electrons, metals are good conductors of electricity and heat.
A metallic structure is typically dense, with closely packed atoms. This can vary, however, depending on the specific structure and type of metal.

Metallic Bonding

The strength of the metallic bond depends on the number of delocalised electrons and the size of the metal ion; generally, the more delocalised electrons available, the stronger the bond.
Metals tend to have low ionization energies and low electron affinities, which allow for the easy formation of cations and the donation of electrons, leading to the creation of metallic bonds.

Alloys

An alloy is a mixture of two or more elements, where at least one element is a metal. Many alloys are made to enhance the properties of metals.
By replacing some of the metal atoms with different atoms of similar size, the regular arrangement of a pure metal lattice can be disrupted. This makes it more difficult for layers to slide over each other, increasing the alloy’s hardness and strength compared to the pure metal.
Familiar alloys include steel (iron and carbon), brass (copper and zinc), and bronze (copper and tin).