PH3 Lewis Structure: Drawings, Hybridization, Shape, Charges, Pair And Detailed Facts


In this article, we are going to study PH3 lewis structure and various facts about it.

PH3 or phosphine is a compound of phosphorus that is classified under pnictogen hydride. Phosphine or phosphane forms bonds by covalent bonding. We can study the bonding in the molecule of PH3 by taking into consideration lewis method. We will study the PH3 lewis structure and understand the concept.

Some facts about Phosphane

PH3 has a molar mass equal to 33.99 g/mol. It exists as a gas that is colorless and has an odor like that of a rotten fish.

The density of PH3 is 1.37 g/L. The melting point of the compound is said to be-132 degrees Celsius and the observed boiling point is somewhere around-87 degrees Celsius. Talking about its solubility, it is soluble in water at a temperature of 17 degrees Celsius (31.2 mg/100mL).

It is also soluble in organic compounds like alcohol, chloroform, benzene, etc. Coming to its preparation, it can be prepared by the treatment of phosphorus (white) and sodium hydroxide. This method is usually used at the industrial level.

How to draw lewis structure for PH3?

To write the PH3 lewis structure one should know the total of all the valence electrons that could be present in the molecule of PH3.

In the structure of phosphane, we can see that there are 3 atoms of hydrogen element one phosphorus element atom is present. Coming to the contribution of phosphorus element in bond formation, we can see there is only one P atom. Meaning the contribution of valence electrons will be only 5 from the P atom. Now counting the contribution of hydrogen element atoms, there are 3 H atoms present.

Coming to the H atom as there are also H atom present in the structure. There are total 3 H atoms, hence contribution by H valence electrons will be 3 times more. Meaning 3×1, which comes up to 3. Now the total valence electrons contribution from both elements it will be 8. As we know the total valence electrons, now we need to know or understand which elements atom will come in the middle or be the central one.

We can predict by taking into account electronegativity of atoms under consideration. The concept that is used to predict that which atom will come in the middle is electronegativity. Meaning the atoms of element participating in bonding must having some electronegativity. What we have to see is among them the atom with less electronegativity will be the middle one. Meaning it will be placed as the central atom.

The other atoms are placed in a manner to satisfy their valence. In PH3 lewis structure the P atom will be placed as the central atom the reason we have already understood. And the hydrogen (H) atom is seen to be the surrounding atom that is placed to satisfy the valency. In this molecule we can see there is sharing of one electron pair between each hydrogen and Phosphorus element atoms. Since one pair of electrons is shared or used for forming bond the resultant bond will be a single bond.

Phosphane lewis structure

We can determine the shape of PH3 by taking into account to concepts by the lewis structure concept and valence shell electron pair repulsion theory concept. 

We will analyze the structure of phosphane by taking into consideration the concept of valence shell electron pair repulsion theory. According to this concept electron pair will prefer to maintain a considerable distance between each other, as this is said to reduce the repulsion in between the valence electrons. And this makes the structure of the molecule stable.

Image credit: Wikipedia

So we cay lone pair tend to affect the shape of the molecule to quite an extent. The number of lone pairs in phosphane molecule are one and this will prefer to maintain a distance from the other bonds. This causes the shape of the molecule to be trigonal pyramid.

PH3 lewis structure formal charges

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

It means there is some type of difference in between the valence electrons and all the (total) electrons (of the atom that is under consideration). Also in this concept it is presumed that in the bonding process when electrons are being shared (in a molecule) they are done in a equal manner. Meaning shared equally. Formula is given below:

V is said to be valence electrons of the atom of the molecule.

N is said to be the figure indicating the unbound (valence) electrons.

B is said to be or includes all the electrons that are shared with other atom.

Number of lone pairs in PH3 lewis structure

The number of lone pairs present in the molecule have a lot of role in the structure prediction.

In the lewis structure of phosphane we can see there are 5 electrons with P as valence electrons and during the process of bonding P will be surrounded by 3 H 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 phosphane molecule will be one.

Hybridization in phosphane

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

Coming to hybridization in the molecule of phosphane, there is no hybridization observed in this molecule. The reason for no hybridization is shape of orbitals of this molecule is quite distinct. And also according to Drago’s rule concept if there is only one lone pair (minimum) at the central atom, then the chances of hybridization are very less.

PH3 lewis structure resonance

By following resonance concept we can explain the delocalised electrons that are present in the molecule.

PH3 Lewis structure octet rule

In the concept of Octet rule an atom must have a complete octet, means the outermost shell should be filled.

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 hydrogen and forms three single bonds.

PH3 polar or nonpolar

Phosphane is a polar molecule, because there is one lone pair present which has electron-electron repulsion which leads to the bent structure of the molecule.

PH3 lewis structure bond angle

As the phosphane structure has a trigonal pyramid shape, the bond angle present in the molecule is equal to 93 degrees.

PH3 uses

  • It is used as a dopant in the industries of semiconductors.
  • Phosphane is also used in plastic industries.

Sania Jakati

This is Sania Jakati from Goa. I am an aspiring chemist pursuing my post graduation in organic chemistry. I believe education is the key element that moulds you into a great human being both mentally and physically. I'm glad to be a member of scintillating branch of chemistry and will try my best to contribute whatever I can from my side and Lambdageeks is the best platform where I can share as well as gain knowledge at the same time. LinkedIn-https://www.linkedin.com/in/sania-jakati-0954101bb

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