Metallic Bonding
Metals that consist of metal cations and they have a balancing number of free electrons also have unit cell structures. These types of metals are known to be crystalline structures which can also be described as either:
- Body Centred Cubic (BCC)
- Hexagonal Close Packed (HPC)
- Face centred Cubic (FCC)
Properties of metals.
- Electrical Conductivity
- High Metal and boiling points
- Lustre
- Thermal Conductivity
- Strength
-
Malleability
Copper
Copper is lightweight and soft metal that has a reddish tint in colour.
Copper and its physical properties.
Melting Point: 1084.62°c
Boiling Point: 2562°c
Young’s Modulus: 110-128 GPa
Density: 8.96g cm-³
Mohs Hardness: 3.0
Vickers Hardness: 369 Mpa
Brinell Hardness: 874 Mpa
Heat Capacity: 25ºC
Electrical resistivity: 200ºC
Thermal Conductivity: 300K
Atomic Radius: 135 Pico metres
(Wikipedia)
Melting and Boiling Points:
Copper has a high melting point and boiling point too as the copper ions have been packed in close together they are found in a fcc structure. Similar to aluminium the copper atoms from one layer arrange themselves so that they then become between the atoms of the layer below. This pattern is then repeated to then build the molecular structure.
Thermal and electrical conductivity:
Copper is also a good thermal conductor because kinetic energy is able to be easily transferred from the closely packed delocalised electrons. Copper is also extremely good at conducting electricity. When there is an electrical potential placed across a strip of copper then the electrons move from the negative to the positive area of the copper and then the current can flow.
Malleability and Ductility:
Copper has positively charged delocalised electrons this is because it is a face centred structure, this makes it malleable and ductile. Copper is similar to aluminium as the layer of copper ions are able to slide over each other. When they have moved they gain new attractions with delocalised electrons in their new positions this then changes the shape of the copper.
Strength
Copper is a strong metal and also has a high tensile strength. This is only when its structure is deformed by applied stress. When this happens the positive ions move and the delocalised electrons move as well this keeps their attraction to the positive ions.
Aluminium
Aluminium is known to be a soft and lightweight metal and has a silvery colour and has a dull grey colour when it is exposed to the air.
Aluminium and its physical properties.
Melting Point: 660.32°c
Boiling Point: 2519°c
Young’s Modulus: 70 GPa
Density: 2.70g cm-³
Mohs Hardness: 2.75
Vickers Hardness: 167 Mpa
Brinell Hardness: 245 Mpa
Heat Capacity: 25ºC
Electrical resistivity: 200ºC
Thermal Conductivity: 300K
Atomic Radius: 125 Pico metres
(Wikipedia)
Melting and Boiling Points:
Because the aluminium ions are packed incredibly close together in the fcc structure then they have a high melting and boiling point. The empty spaces in the structure are filled when the atoms from one later arrange themselves in the spaces of the layer below. When this is repeated over and over again this is when aluminium’s structure is built.
Secondly aluminium has a high melting and boiling point is because of its atomic radius. Aluminium has an atomic radius of 125 picometres. Unlike copper and zinc this makes the attraction of the ions stronger then the others. The smaller the atomic radius is the stronger the attraction between the atoms in the structure.
Thermal and electrical conductivity:
Aluminium is known to be a good thermal conductor as the kinetic energy can be easily transferred from one delocalised electron to the next as they are so closely packed. Because aluminium is a metal it is known to be a good conductor of electricity. This is because of the constant presence of delocalised electrons running through the metallic lattice. When an electric potential is placed across a piece of aluminium then the electrons move from a negative to a positive are of the metal therefore making a current flow.
Malleability and Ductility:
Aluminium is malleable and ductile as it is a face centred cubic structure and is negatively charged. It also the metal inos are able to slide over each other when being shaped. When the metal ions move they produced new attractions with new delocalised electrons, which changes the shape of the aluminium.
Strength
Aluminium is a strong metal but had a low tensile strength compared to other metals when the structure is changed and deformed when stress is applied. This is because the positive ions move and the delocalised electrons move as well maintaining their attraction to the positive ions.