The bond angle of arsenic trichloride (AsCl₃) is 120 degrees.
Arsenic trichloride is a compound where a central arsenic atom forms bonds with three chlorine atoms. The molecular geometry and the specific angles between these bonds are determined by the arrangement of both bonding and non-bonding (lone) electron pairs around the central arsenic atom.
Understanding Arsenic Trichloride (AsCl₃)
Arsenic trichloride is an important inorganic compound characterized by its distinct molecular structure. The central arsenic atom in AsCl₃ has one lone pair of electrons and forms three single covalent bonds with the chlorine atoms. This specific arrangement leads to its characteristic shape and angles.
Key structural aspects that define AsCl₃ include:
- Hybridization: The central arsenic atom undergoes sp3 hybridization. This type of hybridization is typically associated with an electron geometry that would accommodate four electron domains (three bonding pairs and one lone pair in this case).
- Electron Pair Repulsion: The presence of a lone pair of electrons on the central arsenic atom significantly influences the molecule's geometry. Lone pairs exert a greater repulsive force on adjacent electron pairs compared to bonding pairs, which can affect the ideal bond angles.
Molecular Geometry and Bond Angle Explanation
While sp3 hybridization commonly leads to a tetrahedral electron domain geometry (with ideal bond angles of approximately 109.5 degrees), the actual molecular geometry of AsCl₃ is trigonal pyramidal. This is due to the presence of one lone pair and three bonding pairs around the central arsenic atom.
Despite the trigonal pyramidal molecular shape, the bond angle between the chlorine atoms (Cl-As-Cl) within arsenic trichloride is stated to be 120 degrees. Furthermore, the lone pair on the arsenic atom is noted to form a 90-degree angle with the axial single bonds. This detailed angular information provides a comprehensive understanding of the spatial arrangement of atoms and electron density in the AsCl₃ molecule.
Key Characteristics of AsCl₃
To summarize the fundamental structural properties of arsenic trichloride:
- Bond Angle: The Cl-As-Cl bond angle is 120 degrees.
- Hybridization: The central arsenic atom is sp3 hybridized.
- Lone Pair Interaction: The lone electron pair on the arsenic atom is positioned at a 90-degree angle relative to the axial single bonds.
