5 Easy Steps on PI3 Lewis Structure, Hybridization (Solved)

PI3 or Triiodophosphine is an inorganic compound. The bond formation in the molecule of Triiodophosphine can be understood by covalent bonding concept. So we will understand this by analyzing the PI3 lewis structure and facts related to it.

PI₃ (Phosphorus triiodide) has a trigonal pyramidal Lewis structure: a central phosphorus (P) atom with 5 valence electrons, forming single bonds with three iodine (I) atoms, each with 7 valence electrons. One lone pair on P creates <109.5° bond angle. Total of 32 valence electrons used. Electronegativity values: P (2.19), I (2.66), indicating polar bonds. The molecule is polar due to its asymmetrical shape and uneven electron distribution, despite the relatively small electronegativity difference.

Facts about PI3  

The molar mass of Triiodophosphine 411.6 g/mol. In appearance, it exists as solid which has dark red color.

It’s melting point is around 61.2 degrees Celsius and boils at a temperature of 200 degrees Celsius. Its observed density is 4.18 g/cm3. Talking about the reactivity, it’s very when it comes to water. It reacts with water giving phosphorus acid and Iodane. Taking into account its preparation, it can be prepared by adding iodine to solution (white phosphorus + carbon disulfide).

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How to draw lewis structure for PI3?

To understand the lewis dot structure of any molecule we must know the information about the number of valence electrons that are present in the molecule.

Because this valence electrons are important to us as they are the ones which are involved in the process of bonding. In the structure we can see there are 4 atoms that are available for bonding, 3 atoms of the Iodine and one atoms belongs to Phosphorus. So now we will count the valence electrons taking into consideration the outer electronic configuration of the elements that are present in the structure of Triiodophosphine molecule. Phosphorus has 5 electrons as the valence electrons.

Now counting the contribution of iodine element atoms, there are 3 I atoms present. So the number of valence electrons contributed by I will be equivalent to the number 7, as there are 3 I atoms it will be 7×3=21 electrons. But the valency of iodine is one. It would rather give or take one electron and satisfy its octet. So in this molecule it each of the 3 iodine give their valence electrons. In this step we need to find the atom that has to be situated in the middle or center of the molecule.

So on what basis can we conclude which atom will come in the middle? We can predict by taking into account electronegativity of atoms under consideration. So the molecule with less electronegativity when compared to other atoms present in the molecule. The dots around each atoms means the valence electrons of that atom. Over here in this molecule phosphorus will be middle/central atom. Other atoms of iodine will be surrounding it. And the resulting bonds are single bonds.

PI3 lewis structure shape

According to valence shell electron pair repulsion theory lone pair have a great effect in influencing the shape of the molecule.

So in the molecule of Triiodophosphine, there is one lone pair. We know that lone pair prefers to maintain distance from the bonds. Hence the structure is caused to be of trigonal pyramidal shape.

PI3 lewis structure formal charges

What is the meaning of the term formal charge or what we understand by the term formal charge?

The word formal charge means that there is some amount of difference exiting in between the valence electrons (taking into account all the atoms) of the material that is being studied and the total number of electrons that are present in that material or substance. It is said that, while considering the formal charge concept when the bonding type of atoms are shared between the atoms while bonding, they are shared in an equal manner. Below is the formula by using which formal charge can be calculated:

Where V means the number of valence electrons that have been contributed by the atom of the molecule.

N indicates the total valence electrons which are as the unbound on the atom of our study.

B indicates all the total number of electrons that participate in bonding process by sharing electrons with the other atoms.

So in the molecule of Triiodophosphine, the formal charge is nil. There is zero formal charge.

Number of lone pairs in PI3 lewis structure

In the lewis structure of Triiodophosphine we can see there are 5 electrons with P as valence electrons and during the process of bonding P will be surrounded by 3 I atoms forming single bonds. We will see that one pair of electrons will remain unbonded, meaning will not participate in bonding. Hence the number of valence electrons in Triiodophosphine molecule will be one.

Hybridization in Triiodophosphine

We know that hybridization is the concept where in atomic orbitals combine to form hybrid atomic orbitals.

Coming to hybridization in the molecule of Triiodophosphine, it will be sp3 hybridization. Because in the molecule there are 3 bonding pairs and one pair is lone pair, for the accommodation of 4 pairs of electrons it has sp3 hybridization.

PI3 lewis structure resonance

PI3 Lewis structure octet rule

On the basis of octet rule the outer shell of the atoms must have 8 electrons, meaning a complete octet.

So in the molecule of phosphane the valency of phosphorus is 3, so it needs more 3 electrons in order to complete its octet. Hence it takes electrons from three iodine and forms three single bonds.

PI3 polar or nonpolar

As we can see there are three iodine atoms and one atom of phosphorus with one lone pair and three bonding pairs. This gives the molecule of Triiodophosphine a trigonal pyramidal shape. Causing it to have quite low polarity. Hence the molecule is observed to be non polar.

PI3 lewis structure bond angle

As the Triiodophosphine structure has a trigonal pyramid shape, the bond angle present in the molecule is equal to 102 degrees.

PI3 uses

• It is an active component in preparing the compound phosphoric acid by treating PI3 with H2O.
• Important reagent for the process of replacing the groups like hydroxyl by chlorine.

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