In this article, we are going to study PF5 lewis structure and facts related to it.
PF5 or phosphorus pentafluoride is a halide of phosphorus. It’s common name or synonym is Pentafluorophosphorane forms bonds by covalent bonding. The concept of bond formation in pentafluorophosphorane can be studied by understanding the theory of lewis dot structure. So in the below sections, we will understand the phosphorus pentachloride lewis structure and other facts about it in detail.
Some facts pentafluorophosphorane
PF5 has a molecular weight equal to 125.96 g/mol. In appearance, it is observed to be a gas which is colorless and has one so pleasant odor.
It’s observed density is around 5.527 kg/m3. Its observed melting point is -93.78 degrees Celsius and boils at a temperature of -84.6 degrees Celsius. Talking about its preparation, it can be prepared by carrying out fluorination using arsenic trifluoride on phosphorus pentachloride. This method is preferred over other methods and commonly used for preparing pf5.
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How to draw lewis structure for PF5 ?
In order to write the lewis dot structure of pentafluorophosphorane, we must be aware of the total number of valence electrons that are present in the molecule.
In the structure of pentafluorophosphorane, we can see that there are 5 atoms of fluorine and one phosphorus atom is present. So taking into consideration the contribution of phosphorus (valence electrons) as there is only one atom of phosphorus, the number of valence electrons contributed by P will be 5. Now considering the contribution of fluorine atoms, there are 5 F atoms. So the number of valence electrons contributed by F will be equal to 35 (7×5).
Hence the total valence electrons in the molecule of pentafluorophosphorane are 5 + 35 which is equal to 40 electrons.
In the next step the atom that will be in the center has to identified. How do we come to know that which atom will be the center one? It can be judged on the basis of electronegativity.
Meaning the atom in the molecule which has the less electronegativity as compared to the other molecule will be kept in the center of the molecule.in lewis dot structure The dots surrounding the atoms indicate the number of valence electrons. So electrons have to be placed in a arrangement that the valency of all the atoms must be satisfied. In this molecule of pentafluorophosphorane P will be the atom at center and F will be surrounding it.
So bond formation will take place by sharing one electron pair each between P and each F atom. As only one pair of electrons is shared the resulting bond is said to be a single bond.
PF5 lewis structure shape
In PF5 the electron density lies around the central atom of phosphorus as there are 5 bonds and no lone pair present.
This causes the molecule pentafluorophosphorane to have a trigonal bipyramidal shape. In a trigonal pyramidal shape, one atom is placed at the center and the rest atoms (5) are placed at the triangular bipyramidal corners. So in PF5 phosphorus is the central atom and fluorine is placed at the trigonal bipyramidal corners. So equatorial position is acquired by the 3 fluorine atoms and axial position is occupied by the remaining two fluorine atoms.
PF5 lewis structure formal charges
What is the meaning of the term formal charge?
This term means that there exists a difference between valence electrons (all the atoms) of the substance being considered and the total number of electrons present in the substance being considered. It is understood in the concept of formal charge that when atom are being shared between the bonding atoms then they are shared equally. The formal charge formula has been discussed below:
Where the term V indicates the contribution of valence electrons by the atom.
The term N means number of unbound (valence electrons) on an atom that is being considered of molecule.
The term B means the total number of electrons that are shared by bonds with the other atoms in molecule.
So taking into account the formal charge of PF5 molecule it will be zero.
Number of lone pairs in PF5 lewis structure
What we mean when we say lone pair is that the valence electrons that are present in the molecule but do not contribute in bonding process. So when we add up the lone pairs surrounding an atom in a molecule with the total of the electrons that are involved in the process of bonding will give total number of electrons that actually exist in the molecule.
Hybridization in pentafluorophosphorane
So in the molecule of PF5, there exist 3 unpaired electrons that are available for bonding and this are not enough for bonding with five atoms of fluorine. Hence what happens is one electron jumps from 3s orbital to 3d orbital, undergo hybridization, and form hybridized new orbitals. Therefore the hybridization in PF5 molecule will be sp3d. So 5 hybrid orbitals will form bond with 5 atoms of fluorine. And there are 5 sigma bonds present in the molecule.
PF5 lewis structure resonance
PF5 Lewis structure octet rule
According to octet rule, the atoms should have a complete octet meaning its valency has to be satisfied. On this basis, atoms are able to form bonds with various other atoms of different elements.
So in this molecule after undergoing hybridization 5 new hybrid orbitals form bond with each of the 5 atoms of fluorine and satisfy their valence. In this way, it completes it octet.
PF5 polar or nonpolar
So in the molecule of PF5, the charge distribution is symmetric over the central atom of phosphorus. So if the distribution of charge is equal there will be no dipole moment arising. Thus the PF5 molecule is nonpolar.
PF5 lewis structure bond angle
The structure of PF5 is trigonal bipyramidal, 3 of the fluorine atoms are placed at equatorial position forming an angle of 120 degrees and 2 atoms of fluorine are placed at an axial position ( axial-equatorial) bond is 90 degrees.
- It is used for chlorinating processes and also acts as a catalyst in producing chemicals (organic), dyestuffs.
- Also an active agent in process of producing acid chlorides, important catalyst in the reactions such as condensation, cyclisation.
- Has a role of great importance in pharma industries as active component in making of cephalosporin and antibiotics such as penicillin.