What is aluminum? :
The aluminum is a chemical element whose acronym is Al, has an atomic number equal to 13 and a number of mass approximately equal to 27 u ( “u” means atomic mass unit and represents 1/12 of the atomic mass of carbon element) . Thus, an aluminum atom is 2.25 times heavier than a carbon atom.
It is a metallic element and is located in the third period of the Boro family (family IIIA), in the Periodic Table, being, therefore, a representative element.
Content Index :
- 1 General characteristics
- 2 Atomic characteristics
- 3 Physical properties
- 4 Chemical properties
- 5 Availability in nature
- 6 Ways to obtain
- 6.1 Bayer method
- 6.2 Hall-Heroult method
- 7 Aluminum Alloys
- 8 Applications
General characteristics of aluminum :
- Group: 2
- Symbol: Al
- Density = 2,702 g.cm/3
- Electronic configuration: [Ne] 3s2 3p1
- PE (boiling point) = 2467 °
- PF (melting point) = 660 ° C
- Classification: metal
- Color: Silver
- Structure: cubic centered on the faces.
- Year of discovery: 1825
- Discoverer: Hans Christian Oersted
Atomic characteristics of aluminum :
Since the atomic number and mass number of aluminum are, respectively, 13 and 27, the amount of particles present in an atom of this element is:
- 13 protons, since the atomic number is 13.
- 13 electrons, since the atomic number is 13.
- 14 neutrons (difference between mass number (27) and atomic number (13)).
As we can see, the most energetic sublevel (the last place to receive energy) of an aluminum atom is 3p1. The geometric distribution confirms that 3p1 is also the outermost sub-level of the aluminum atom.
Physical properties of aluminum :
The main physical properties of aluminum are:
- Physical state at room temperature: solid.
- Melting point: the temperature at which aluminum ceases to be solid and becomes liquid is 660 ° C.
- Boiling point: the temperature at which aluminum ceases to be liquid and becomes gaseous is 2470 ° C.
- Electrical conductivity: aluminum is a metal of high electrical conductivity, which can be compared with copper.
- Thermal conductivity: aluminum is a metal with high thermal conductivity.
- Density: the density of aluminum is 2.7 g / mL. It is the nonferrous metal of lower density.
- Maleabilidad: the aluminum is a very malleable metal, that is to say, that has the capacity to adapt to the form that we want.
OBS: We can always recycle aluminum, regardless of the use or form it had before.
Chemical properties of aluminum :
The main chemical properties of aluminum are:
- Corrosion resistance: Aluminum has a high resistance to corrosion, that is, it does not oxidize easily in the presence of moisture and air.
- Chemical bond : Aluminum makes a metal bond between its atoms.
- Interactions: The aluminum atom is able to interact with non-metal atoms and with the hydrogen atom through ionic bonds, forming different ionic compounds.
Availability of aluminum in nature:
Aluminum is found in nature only as a mineral, that is, it is part of the composition of a mineral substance. The most common mineral in which we find aluminum is bauxite:
Bauxite: is a mineral that has hydrated aluminum oxide (Al2O3.xH2O).
Ways to obtain aluminium :
Two fundamental methods are required to obtain aluminum: the Bayer method and the Hall-Heroult method .
The method Bayer is used for aluminum oxide (Al2O3), also called alumina. In this method, the water particles are separated from the aluminum oxide (Al2O3). These are the stages:
- Stage 1: The bauxite is ground in a crusher.
- Stage 2: The ground bauxite is mixed with a solution of sodium hydroxide and taken to an autoclave;
- Stage 3: After heating, the mixture is cooled and goes through the sedimentation and filtration processes for the extraction of chemical reaction residues, such as iron oxide, titanium, calcium carbonate, etc.
- Step 4: The filtrate is then treated with gibbsite (calcium-containing mineral) to form aluminum hydroxide Al (OH) 3;
- Step 5: Finally, the aluminum hydroxide formed is subjected to washing and calcination (mixing with calcium carbonate CaCO3, and heating) for the formation of aluminum oxide (Al2O3).
The Hall-Heroult method uses alumina obtained by the Bayer method to produce pure aluminum.
In this method the igneous electrolysis of the alumina is performed. The steps are the following:
- Step 1: The alumina is mixed with cryolite ore (Na3AlF6), which lowers the melting point of the alumina from 2000oC to 1000oC;
- Step 2: Then, the mixture is subjected to about 1000 ° C to melt (and enter the liquid state);
- Step 3: The melted mixture (alumina and cryolite) is placed in an electrolytic tank and subjected to an electric current. With this, the aluminum of the alumina is reduced and forms the aluminum (Al (s)).
Aluminum is widely used in the form of metal alloys. These alloys are formed from the simple mixing of aluminum with other metals or nonmetals. Below are some examples of aluminum alloys:
- Aluminum alloy (Al) and copper (Cu)
- Aluminum alloy (Al), copper (Cu) and silicon (Si)
- Aluminum alloy (Al), magnesium (Mg) and silicon (Si)
- Aluminum alloy (Al), zinc (Zn) and copper (Cu)
- Aluminum alloy (Al) and lithium (Li)
- Aluminum alloy (Al) and magnesium (Mg)
- Aluminum alloy (Al) and silicon (Si)
- Aluminum alloy (Al) and manganese (Mn)
Applications of aluminum :
Aluminum is a very important metal in our lives because it has many applications and uses such as:
- Used as electrical cable.
- Production of beverage cans in general.
- Used in the manufacture of vehicle structures.
- Production of kitchen utensils.
- Door and window construction.
- Production of aeronautical parts, etc.