Determine the electron pair geometry and molecular shape of CBr
using Lewis structure. Are the bonds in this molecule polar or nonpolar? Is the overall molecule polar or nonpolar? Explain your answer.
The Correct Answer and Explanation is:
Let’s break this down step by step:
Step 1: Lewis Structure of CBr
Carbon (C) is in Group 14, and bromine (Br) is in Group 17 of the periodic table. For the molecule CBr, we assume a simple C–Br single bond.
- Valence electrons:
- Carbon has 4 valence electrons.
- Bromine has 7 valence electrons.
- Drawing the structure:
- Carbon will form a single bond with bromine. Each bond involves two electrons, so that’s 2 electrons used.
- After bonding, carbon has 2 electrons left to complete its valence shell.
- Bromine has 5 remaining electrons, so it will form 3 lone pairs.
So, the structure is:
rubyCopyEdit:Br - C:
- Carbon has 4 valence electrons, 2 of which are used in the bond with bromine, leaving 2 electrons as a lone pair.
- Bromine has 7 valence electrons, 2 used for bonding, leaving 5 electrons as 3 lone pairs.
Step 2: Electron Pair Geometry and Molecular Shape
Now, let’s determine the geometry of the molecule.
- Electron pairs around carbon: There are two electron pairs around the carbon atom (one bonding pair with bromine and one lone pair).
- Since we have two regions of electron density, the electron pair geometry will be linear.
- Molecular Shape: When considering the molecular shape (which only accounts for the positions of the atoms), the shape will be linear as well. The lone pair on carbon doesn’t influence the shape in this case because it’s just one lone pair.
Step 3: Bond Polarity
Next, let’s examine the bond polarity. The C–Br bond is polar because bromine is more electronegative than carbon. This creates a dipole where the electron density is shifted towards the bromine atom.
Step 4: Overall Molecular Polarity
To determine whether the overall molecule is polar or nonpolar, we consider the vector sum of the bond dipoles.
- Since the molecule is linear and there is a polar bond (C–Br), the overall molecular dipole will be in the direction of the C–Br bond, making the molecule polar.
Conclusion:
- Electron pair geometry: Linear
- Molecular shape: Linear
- Bond polarity: The C–Br bond is polar.
- Overall molecular polarity: The molecule is polar because it has a polar bond and there is no symmetry to cancel out the dipole.
This explanation shows that CBr (presumably meant to represent a molecule like CBr4) has polar bonds, and the molecular polarity depends on its shape and symmetry.
