The key difference between aluminium and alumina is that the aluminum is a chemical element, and alumina is an aluminium containing compound.
Although the two terms aluminium and alumina sound similar, they are different. Alumina is a compound, which includes aluminium chemical element. Likewise, there are several other important differences between aluminium and alumina that we are going to discuss in this article.
CONTENTS
1. Overview and Key Difference
2. What is Aluminium
3. What is Alumina
4. Side by Side Comparison – Aluminium vs Alumina in Tabular Form
5. Summary
What is Aluminum?
Aluminium (Al) is a chemical element in the group 3 and period 3, which has the atomic number of 13. The electron configuration of this element is 1s2 2s2 2p6 3s2 3p1. And, the atomic weight of it is about 27 g mol-1. We can categorize this element as a metal. In fact, it is the most abundant metal in the earth crust.
Moreover, aluminium is a silvery white solid. It is a durable and lightweight metal. Also, it is a low density metal. Furthermore, it is not soluble in water at room temperature. At the same time, it has excellent conductivity of electricity. Besides, this metal doesn’t easily ignite.
Figure 01: Aluminum Foil
More importantly, aluminium shows both metallic and nonmetallic characteristics; hence, it is amphoteric. Therefore, we can categorize it as a metalloid rather than as metal. As a metallic characteristic, it reacts with acids releasing hydrogen gas forming the +3 charged aluminium ion. As a nonmetallic characteristic, it reacts with hot alkali solutions and form aluminate ions.
Since this metal is too reactive to stay in its free form, naturally it occurs in mineral forms. Here, the main aluminium containing mineral is bauxite. Also, it occurs in minerals such as cryolite, beryl, garnet, etc.
Among the uses of this metal, the major use is in automobiles and other vehicles manufacturing, construction, paints, for household items, packaging, etc., due to its low density and resistance to corrosion. Pure aluminium is soft and lacks the strength to use it, but we can mix it with other elements like iron or silicon (in small amounts) to increase the strength and hardness.
What is Alumina?
Alumina is the oxide of aluminium with the formula Al2O3. It is a white colour crystalline solid. Since aluminium is too reactive, we cannot find it naturally in free form (very rarely, we can find free Al). In nature, aluminium occurs covered with an oxide layer, and this surface aluminium oxide layer protects it from corrosion.
Figure 02: Alumina Flakes
Moreover, the molecular weight of alumina is about 102 g mol-1. Its melting point and boiling points are very high, which are over 2000 oC. Also, this compound is water-insoluble but very hygroscopic. Furthermore, alumina cannot conduct electricity, but it is a thermal conductor. Since aluminium is an amphoteric element, aluminium oxide is also an amphoteric oxide.
Alumina occurs commonly in the form of corundum, which is s crystalline mineral. It is useful in producing aluminum metal by the Hall process. In this process, alumina is dissolved in molten cryolite, and the resulting salt is electrolyzed. After that, we can obtain the pure aluminium metal.
Moreover, we can use this compound as an abrasive due to its hardness and strength. It is also useful as a catalyst to enhance chemical reaction rates. In addition, it is useful as a water absorber to purify gases and filler for plastics.
What is the Difference Between Aluminium and Alumina?
Aluminium is a chemical element having the atomic number 13, and chemical symbol Al. Alumina is a chemical compound having the chemical formula Al2O3. Therefore, the key difference between aluminium and alumina is that the aluminum is a chemical element, and alumina is an aluminium containing compound. Moreover, a significant difference between aluminium and alumina is that the aluminium is a good electrical conductor while alumina is an electrical insulator.
Another notable difference between aluminium and alumina is that the aluminium is largely reactive with oxygen, acids, or bases but, alumina is not too reactive like aluminium. The below infographic shows more details on the difference between aluminium and alumina.
Summary – Aluminium vs Alumina
Alumina is a chemical compound containing the aluminium chemical element. Therefore, the key difference between aluminum and alumina is that Aluminum is a chemical element, and alumina is an aluminium containing compound.
Reference:
1. Britannica, The Editors of Encyclopaedia. “Alumina.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 28 Nov. 2018. Available here
Image Courtesy:
1.”37841673644″ by Marco Verch (CC BY 2.0) via Flickr
2.”SEM of coated alumina flake”By Unknown – Merck KGaA Germany, Performance Materials Division, (CC BY-SA 3.0) via Commons Wikimedia