Answer the following questions regarding NF3, a. How many total number of valence electrons NF3 has? b. Draw the Lewis structure. c. What is electron geometry? d. What is molecular geometry? e. Is NF3 polar or non-polar ? Explain.
The Correct Answer and Explanation is:
Let’s break down the answers to your questions about NF3 (Nitrogen trifluoride):
a. Total Number of Valence Electrons in NF3
To calculate the total number of valence electrons in NF3, we need to count the valence electrons from each atom:
- Nitrogen (N) is in Group 15 of the periodic table, so it has 5 valence electrons.
- Fluorine (F) is in Group 17, so each fluorine atom has 7 valence electrons.
Since there are three fluorine atoms in NF3, the total number of valence electrons is:
- 1 nitrogen atom × 5 electrons = 5 electrons
- 3 fluorine atoms × 7 electrons = 21 electrons
So, the total number of valence electrons in NF3 is:
5 + 21 = 26 valence electrons.
b. Lewis Structure of NF3
To draw the Lewis structure:
- Place the nitrogen (N) atom in the center since it is less electronegative than fluorine.
- Attach the three fluorine (F) atoms to nitrogen by single bonds.
- Distribute the remaining electrons. After forming three bonds, 6 electrons (2 electrons per bond) are used. The remaining 20 electrons will be distributed as lone pairs.
- Place 3 lone pairs of electrons on each fluorine atom to complete their octets (fluorine atoms need 8 electrons to complete their valence shell).
- Place 1 lone pair on the nitrogen atom to ensure nitrogen also has 8 electrons around it.
The final Lewis structure will have:
- Three single bonds between nitrogen and fluorine.
- Each fluorine atom with 3 lone pairs.
- Nitrogen will have one lone pair.
c. Electron Geometry
The electron geometry of NF3 is based on the number of electron pairs around the central nitrogen atom. Since there are three bonding pairs and one lone pair of electrons around nitrogen, the electron geometry is tetrahedral. This is because the electron pairs around nitrogen will arrange themselves in a tetrahedral shape to minimize electron-electron repulsion.
d. Molecular Geometry
The molecular geometry takes into account only the positions of the atoms, ignoring the lone pairs of electrons. Since there are three bonded atoms and one lone pair, the molecular geometry of NF3 is trigonal pyramidal. This shape arises because the lone pair on nitrogen pushes the fluorine atoms slightly downward, creating a pyramid-like structure with the nitrogen atom at the apex.
e. Is NF3 Polar or Non-Polar? Explain
NF3 is polar because:
- The nitrogen-fluorine bonds are polar due to the large electronegativity difference between nitrogen (3.04) and fluorine (3.98). Fluorine pulls electron density toward itself, creating partial negative charges on the fluorine atoms and a partial positive charge on the nitrogen.
- The molecular geometry of NF3 is trigonal pyramidal, which means the bond dipoles do not cancel out. The lone pair on nitrogen contributes to the asymmetry of the molecule, creating a net dipole moment, making NF3 a polar molecule.
In summary:
- Valence electrons = 26
- Electron geometry = Tetrahedral
- Molecular geometry = Trigonal pyramidal
- Polarity = Polar due to the asymmetry of the molecule and bond dipoles not canceling.
