EXPERIMENT 8: Draw the Lewis structure for KrCls. Show the calculation of the formal charges for
each atom and label each atom with the correct formal charge. (2pts)
What is the electron geometry? (1pt)
What is the molecular geometry? (1pt)
What is the hybridization? (sp, sp3, etc.) (1pt)
What is/are the approximate bond angle/s? (1pt)
The Correct Answer and Explanation is :
Lewis Structure for KrCl₃:
To start, let’s break down the Lewis structure for krypton trichloride (KrCl₃).
- Total Valence Electrons:
- Krypton (Kr) is in Group 18, so it has 8 valence electrons.
- Each chlorine (Cl) atom is in Group 17 and has 7 valence electrons. Since there are three chlorine atoms, the total number of valence electrons from chlorine is 3 * 7 = 21 electrons.
- Total valence electrons = 8 (from Kr) + 21 (from 3 Cl) = 29 valence electrons.
- Structure:
- Krypton (Kr) is the central atom because it is less electronegative than chlorine (Cl).
- Each chlorine atom will form a single bond with krypton, using 2 electrons per bond. Three bonds will account for 6 electrons, leaving 29 – 6 = 23 electrons.
- The remaining 23 electrons will be placed as lone pairs on the chlorine atoms. Each chlorine atom will receive 3 lone pairs (6 electrons) to complete its octet. This will consume 18 electrons, leaving 5 electrons to be placed as lone pairs on krypton.
- Formal Charge Calculation:
- Formal charge = Valence electrons – (Lone pair electrons + ½ bonding electrons).
- For krypton: Formal charge = 8 – (5 lone electrons + 3 bonding electrons/2) = 8 – (5 + 3/2) = 8 – 6.5 = +1.
- For each chlorine: Formal charge = 7 – (6 lone electrons + 1 bonding electron/2) = 7 – (6 + 1/2) = 7 – 6.5 = 0.
Electron Geometry:
The electron geometry is determined by the arrangement of electron pairs around the central atom. For KrCl₃, there are 3 bonding pairs and 1 lone pair on krypton. The electron geometry is tetrahedral.
Molecular Geometry:
Since there is one lone pair on krypton, the molecular geometry is trigonal pyramidal.
Hybridization:
Krypton undergoes sp³ hybridization because it has four electron regions (3 bonding regions and 1 lone pair).
Bond Angles:
In a tetrahedral geometry, the ideal bond angle is 109.5°. However, the presence of a lone pair slightly compresses these angles, so the bond angle is slightly less than 109.5°.
I’ll generate a visual representation of this structure.
Here is the Lewis structure for KrCl₃, showing the electron geometry, molecular geometry, formal charges, and the bond angles. The structure indicates sp³ hybridization and the trigonal pyramidal molecular shape. Let me know if you need further clarification!
