Draw the Lewis structure of SbBr3 and use it to answer the following questions: What is the electron domain geometry of this molecule? [Select ] What is the molecular geometry of this molecule? [Select ] Is this molecule polar? [Select ] What is the approximate value of the Br-Sb-Br bond angle in this molecule? [Select ] What is the bond order of the Sb-Br bonds in this molecule? [Select ]
The Correct Answer and Explanation is:
Here are the correct answers based on the Lewis structure of SbBr₃ (antimony tribromide), followed by a detailed explanation:
Correct Answers:
- Electron domain geometry: Tetrahedral
- Molecular geometry: Trigonal pyramidal
- Is this molecule polar?: Yes
- Approximate Br-Sb-Br bond angle: <109.5°
- Bond order of Sb-Br bonds: 1
Explanation
To determine the geometry and other properties of SbBr₃, we start with its Lewis structure. Antimony (Sb), in Group 15 of the periodic table, has 5 valence electrons. Each bromine atom (Br), from Group 17, has 7 valence electrons. In SbBr₃, Sb forms three single covalent bonds with three Br atoms.
Step 1: Lewis Structure
- Sb is the central atom.
- It forms three single bonds with Br atoms (each Br needs only one electron to complete its octet).
- This uses 3 of Sb’s 5 valence electrons.
- The remaining 2 electrons form a lone pair on Sb.
Step 2: Electron Domain Geometry
- There are four electron domains (3 bonding pairs + 1 lone pair) around Sb.
- This corresponds to a tetrahedral electron domain geometry.
Step 3: Molecular Geometry
- Because one of the electron domains is a lone pair, the molecular shape is not tetrahedral but trigonal pyramidal (like NH₃).
Step 4: Polarity
- Due to the lone pair, the molecule is not symmetric, and the dipole moments do not cancel.
- Thus, SbBr₃ is polar.
Step 5: Bond Angle
- Ideal tetrahedral bond angle is 109.5°.
- The lone pair exerts more repulsion, reducing the angle to slightly less than 109.5°, typically around 107°.
Step 6: Bond Order
- Each Sb-Br bond is a single bond, so the bond order is 1.
In summary, SbBr₃ has a tetrahedral electron geometry, trigonal pyramidal molecular geometry, is polar, has Br-Sb-Br bond angles <109.5°, and each Sb-Br bond has a bond order of 1.
