Chem Explorers

Aluminum Chloride: A Versatile Compound with Industrial and Scientific Applications

Aluminum Chloride: What You Need to Know

Aluminum chloride is a compound with numerous industrial and scientific uses. We will delve into its nature, formation, and physical and chemical properties.

Aluminum chloride, also known as AlCl3, is a white to yellowish solid that readily absorbs moisture from the air, making it hygroscopic. It has a pungent odor and is highly reactive, making it valuable in many industrial processes.

Physical Properties

Aluminum chloride exists in three states: solid, liquid, and gaseous. In its solid form, it appears as a white to yellowish powder. In its liquid form, it is an amber-colored liquid. In its gaseous state, aluminum chloride is a highly reactive and corrosive gas with a yellow-green color.

Chemical Properties

Aluminum chloride is acidic. When dissolved in water, it forms an acidic solution. It is also a Lewis-acid catalyst, meaning it accepts electron pairs from other molecules during chemical reactions. This property makes it valuable in organic chemistry, where it acts as a catalyst in various reactions.

Formation of Aluminum Chloride

Aluminum chloride is formed by reacting aluminum metal with chlorine gas or hydrogen chloride gas at high temperatures. The reaction is highly exothermic, releasing a significant amount of heat.

Formation of Hexahydrates

Aluminum chloride can also form hexahydrates, compounds containing six water molecules per molecule of aluminum chloride. Hexahydrate forms when aluminum oxides dissolve in hydrochloric acid. The resulting solution is then evaporated, leading to the crystallization of the hexahydrate compound.

Applications of Aluminum Chloride

Industrial Applications

  • Production of aluminum metal, a crucial raw material for various industries.
  • Production of dyes, pigments, and pharmaceuticals.

Organic Chemistry Applications

  • Friedel-Crafts alkylation
  • Friedel-Crafts acylation
  • Synthesis of carboxylic acids

Safety Considerations

Aluminum chloride is highly reactive. Contact with water can generate heat, leading to the release of hydrogen chloride gas. Therefore, it is crucial to handle it with care and use appropriate protective equipment.


Aluminum chloride is a useful compound with numerous industrial and scientific applications. Its physical and chemical properties make it versatile, serving as both an acid and a Lewis-acid catalyst. The formation of aluminum chloride involves high temperatures, and its reactivity necessitates careful handling. Overall, aluminum chloride plays a vital role in industry and science, making it an important compound to understand.

Lewis Structure of Aluminum Chloride

Valence Electrons and Atomic Number

Understanding the Lewis structure of molecules is crucial in grasping their chemical properties and reactivity. Aluminum has three valence electrons, while chlorine has seven. The atomic number of aluminum is 13, and chlorine’s atomic number is 17.

Lewis Structure Assembly

To assemble the Lewis structure of aluminum chloride, we begin by drawing a skeletal structure. This structure shows how the atoms are bonded together using chemical bonds. Aluminum chloride consists of one aluminum atom and three chlorine atoms bonded together. The aluminum atom is in the center due to its lower electronegativity compared to chlorine. The three chlorine atoms are bonded to the aluminum atom.

Outer Shell Requirements

Next, we draw electrons around each atom to satisfy its outer shell requirement. This requirement is the number of electrons an atom needs to complete its outermost shell or valence shell. Aluminum needs to gain three electrons to complete its outer shell with eight electrons. Chlorine needs only one electron to complete its outer shell with eight electrons. In the Lewis structure, the aluminum atom has three lone pair electrons around it, and each chlorine atom has one lone pair of electrons.

Aluminum Chloride Hybridization

To determine the hybridization of aluminum chloride, we use the VSEPR theory and the steric number. The steric number is the sum of the number of bonded atoms and the number of lone pair electrons around an atom. The aluminum atom in aluminum chloride has a steric number of four because it has three chlorine atoms bonded to it and one lone electron pair. Therefore, the aluminum atom is sp2 hybridized.

Aluminum Chloride Angles

The geometry of molecules depends on the repulsion between electrons. The VSEPR theory helps us determine the bond angles in aluminum chloride. The three chlorine atoms are arranged in a trigonal planar geometry around the aluminum atom. In a trigonal planar geometry, the bond angle between the central atom and the surrounding atoms is 120 degrees.

Aluminum Chloride Molecular Geometry and Shape

The molecular geometry and shape of a molecule are essential in determining its properties and behavior. The A-X-N method helps determine the molecular geometry and shape of aluminum chloride. A stands for the central atom, X stands for the surrounding atoms, and N represents the number of lone pair electrons around the central atom. In aluminum chloride, the central atom is aluminum, and the surrounding atoms are three chlorine atoms. There is one lone electron pair around the aluminum atom. Therefore, the A-X-N notation for aluminum chloride is AX3E. The molecular geometry of aluminum chloride is trigonal planar, and its shape is bent. The bent shape is due to the presence of a lone pair of electrons around the aluminum atom.


The Lewis structure of aluminum chloride provides crucial information about its chemical properties. In aluminum chloride, the aluminum atom has three lone pair electrons, and each chlorine atom has one lone pair of electrons. The trigonal planar geometry of aluminum chloride is due to the repulsion forces between electrons. Understanding the shape and geometry of aluminum chloride is essential in knowing how it behaves in different chemical reactions.

Aluminum chloride has many industrial applications, including organic synthesis, alkylation, and acylation of arenes. In conclusion, Aluminum Chloride has many physical and chemical properties that make it a versatile compound with industrial and scientific applications. Its Lewis structure, hybridization, and molecular geometry explain its reactivity and shape. The high reactivity of aluminum chloride requires careful handling in industry and research.

Some key takeaways: Aluminum chloride is acidic and a Lewis-acid catalyst; organic synthesis can use it for alkylation, acylation of arenes, and other chemical reactions. It is essential to understand its properties to use it effectively and safely.


  1. What is Aluminum Chloride used for? Aluminum Chloride is used in many industrial processes, including the production of aluminum, dyes, pigments, and pharmaceuticals. It is also used as a Lewis-acid catalyst in organic chemistry.
  2. Is Aluminum Chloride safe to handle? Aluminum chloride is highly reactive and should be handled with care. If it comes into contact with water, it can generate heat and release hydrogen chloride gas.
  3. How is the Lewis structure of Aluminum Chloride determined? The Lewis structure of Aluminum Chloride is determined based on the valence electrons of aluminum and chlorine atoms, drawing a skeletal structure, satisfying the outer shell requirements, and determining its hybridization.
  4. What is the molecular geometry of Aluminum Chloride? The molecular geometry of Aluminum Chloride is trigonal planar, and its shape is bent, thanks to the lone pair of electrons around the aluminum atom.
  5. What are the applications of Aluminum Chloride in organic synthesis? Aluminum Chloride is commonly used as a Lewis-acid catalyst in organic synthesis, including Friedel-Crafts alkylation, acylation of arenes, and the synthesis of carboxylic acids.

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