P2H4 Lewis Structure & Characteristics: 15 Complete Facts

Diphosphine(P2H4) is an inorganic compound with different chemical properties. Let us study the lewis structure of P2H4.

P2H4 has a molecular weight of 65.9 g/mol and is also known as diphosphate. It melts at a temperature of 99 degrees Celsius, and it boils at a temperature of 63.5 degrees Celsius. The less symmetrical gauche shape is adopted by diphosphine at a P-P distance of 2.219 angstroms.

Let us go through the P2H4 Lewis structure, shape, valence electrons, hybridization, and more in detail below.

How to draw P2H4 lewis structure?

A Lewis electron dot structure describes all the bonds in a molecule, including the final lone pairs between the bonding atoms. Let us draw the P2H4 Lewis structure below.

The total number of valence electrons in P2H4:

P2H4 molecules have a total of 14 valence electrons. The periodic table’s group 15 element is phosphorus. Consequently, there are 5 valence electrons in phosphorus. Group 1 of the periodic table contains hydrogen. Thus, hydrogen has a valence electron of 1.

Select the central atom in P2H4:

The centre atom is a phosphorus atom (P), and the outer atoms are hydrogen atoms (H). When comparing the electronegativity of hydrogen (H) to phosphorus (P), hydrogen is less electronegative. But if the provided molecule contains hydrogen, then always place the hydrogen outside.

Put an electron pair between each atom to link them together:

The P2H4 molecule is formed by the chemical connection and illustrates a chemical link between the phosphorus-phosphorus and phosphorus-hydrogen atoms, placing a pair of two electrons between them.

Complete the octet (or duplet) in P2H4:

  • Hydrogen is the outer atom and forms a duplet in the  P2H4 Lewis structure since it only needed two electrons to finish off its outer shell. 
  • The centre phosphorus atom, on the other hand, needed two electrons to complete its octet.
  • And once the hydrogen duplet was completed, four valence electrons were left over, which were used to complete the octet of each phosphorous atom.

The stability of the P2H4 Lewis structure must be verified in the final phase:

A concept of formal charge can be used to verify the stability of Lewis structures. Both the hydrogen (H) and phosphorus (P) atoms have a formal charge of zero. The below-mentioned P2H4 structure is unchanged and has a stable Lewis structure. The image of the Lewis structure of P2H4 is shown below:

p2h4 lewis structure
 Lewis structure of P2H4

P2H4 lewis structure formal charge

By computing the formal charge on each atom, it is determined whether the Lewis structure is stable or not. Let us find out the formal charge in P2H4.

P2H4 has a formal charge of Zero. The formal charge calculation is done by using the formula;

F.c(Formal Charge) of P2H4 =(V.E) valence electrons in the free state of P2H4 – (N.E)nonbonding electrons in P2H4 – ½(B.E)bonding electrons in P2H4.
The formal charge table on P2H4 is shown below:

Atoms involved
in P2H4
Central Atom
526/2(5- 2- 6/2)
Outer Atom
102/2(1- 0- 2/2)
The F.C on P2H4 lewis structure, P = 0, H=0, P2H4 =0

P2H4 valence electrons

The electrons that are found in an atom’s most outer orbit are known as valence electrons. Let us calculate the valence electron in P2H4.

The P2H4 molecule has a total of 14 valence electrons.

  • Each phosphorus (P) atom contributes five valence electrons.
  • Each hydrogen (H) atom contributes one valence electron.
  • Thus, the P2H4 molecule has Valence electrons= (5(2) + 1(4) = 14).

P2H4 lewis structure octet rule

The octet rule explains how an atom would naturally try to obtain, lose, or share electrons to achieve 8 electrons. Let us check whether P2H4 satisfied the octet rule or not.

P2H4 satisfies the octet rule. The hydrogen atoms collectively form a duplet. Additionally, the structure above uses just 10 of the valence electrons from the P2H4 molecule.

  1. The P2H4 molecule has a total of 14 valence electrons.
  2. Thus, 14 – 10 = 4 is the remaining number of electrons that must be maintained on the core phosphorus atoms.
  3. Therefore, these four electrons, or two pairs of electrons, are on the centre phosphorus atoms.
  4. There are 8 electrons in each phosphorus atom. The phosphorus atoms are therefore stable and the octet rule is satisfied.

P2H4 lewis structure lone pairs

An atom’s valence electron pair known as a lone pair is not involved in the formation of bonds. Let us determine how many lone pairs there are in P2H4.

P2H4 molecule consists of one lone pair at each phosphorous atom. These lone pairs complete the phosphorus octet while not taking part in the bonding. As a result, the core atom of P2H4 has two lone pairs(14-10=4) on two phosphorous in its Lewis structure.

P2H4 lewis structure shape

The equilibrium state of the molecule, when it has the lowest energy in the system, is described as the shape. Let us examine the P2H4 molecule shape.

P2H4 has a tetrahedral shape and a pyramidal geometry. A phosphorous atom consists of two hydrogen atoms, one on the left and one on the right. Phosphorus’ single pair electron and the shared pair electrons surrounding it will resist one another.

  • They will consequently be forced apart, and a trigonal pyramidal will be present on each phosphorous side.
  • P2H4 molecular geometry is pyramidal.
  • Tetrahedral P2H4 Electron Geometry, according to VSEPR AX3n1 model.
  • The image is shown below:
p2h4 lewis structure
3D representation of P2H4 lewis structure shape

P2H4 hybridization

The total number of bound atoms surrounding a core atom and the lone pair it has adds to the hybridization number. Let us find out the hybridisation in P2H4.

P2H4 lewis structure has Sp3 hybridisation. The number of bonded atoms bound to phosphorous plus the number of lone pairs on phosphorous equals the number of hybridizations of P2H4.

  • One lone pair and three bonded atoms on the phosphorous, as per the P2H4 Lewis dot structure. 
  • Therefore, P2H4 has a hybridization number of (3 + 1) = 4. 
  • For a hybridization number of four, each phosphorus atom in the P2H4 molecule undergoes Sp3 hybridization.

P2H4 lewis structure angle

The angle between two nearby bonds, measured geometrically, is known as a bond angle. Let us talk about the P2H4 bond angle.

In P2H4, the bond angle between H-P-H and P-P-H will both be between 96.2° and 94°. The bond angle of atoms with Sp3 hybridization is typically 109.5°. Lower the bond angle to a certain extent since each phosphorus atom in P2H4 has one lone pair.

Is P2H4 solid or liquid?

As long as all the molecules of a substance are densely packed and have a consistent shape, it is considered solid. Let us find out whether P2H4 is solid or liquid.

P2H4 is a colourless liquid rather than a solid. Because of the weak P-P bond, the state of the molecule is liquid. One of several binary phosphorus hydrides is this colourless fluid. Typically, impurities are what cause phosphine samples to catch fire in the air.

Is P2H4 soluble in water?

A molecule’s solubility in water depends on the nature and condition of its solubility. Let us check to see if P2H4 dissolves in water or not.

P2H4 dissolves very slowly in water.  But it is sparingly soluble in other organic solvents. When kept, diphosphine (P2H4) spontaneously catches fire and decomposes.

Is P2H4 polar or nonpolar?

The polarity and non-polarity of molecules are controlled by their geometry and structural patterns. Let us check whether the P2H4 is polar or not.

The P2H4 molecule is non-polar. It has one lone pair on each phosphorous and Sp3 hybridization on both phosphorous. A P-P bond is created by one hybrid of each orbital. 

  • However, the P-P bond is non-polar since it has the same electronegativity, whereas the P-H bond is polar because phosphorous and hydrogen have slightly different electronegativities.
  • P2H4 molecule is non-polar because lone pairs present on phosphorous try to repel bonded pairs.
  • The presence of lone pairs on each Phosphorous distorts the structure of the molecule. Therefore, it is pointless for them to neglect the dipole moment created by the link.
  • The dipole moment of 0 D is the sum of the moments of the four P-H bonds and the two lone electron pairs. 
  • P2H4 is a non-polar molecule as a result.

Is P2H4 molecular compound?

Groups of two or more atoms that are chemically bonded together are referred to as molecules. Let us see whether  P2H4 is molecular or not.

P2H4 is a molecular compound because it is a stable molecule with the same chemical formula as hydrazine (NH2-NH2). Each of the two phosphorus atoms in an sp3 hybrid has three bond pairs and a single pair of electrons.

  • The phosphorus-phosphorus and phosphorus-hydrogen atoms interact chemically to form the P2H4 molecule.
  • This result would have been the formation of a pyramidal configuration.

Is P2H4 acid or base?

Lewis bases can offer a single pair of electrons, although the chemical compound salt has no net charge. Let us check whether  P2H4 is acid or not.

P2H4 acts as a slight basic character. Because both phosphorous contain lone pairs of electrons that are easily donated to the electrophile. In general, bases are electron pairs donar. 

  • It doesn’t behave like an acid since the polarity of the bonds isn’t much higher
  • But because hydrogen is tightly bound to the P atoms.
  • Its pH is found to be close to 6, making it a very weak acid.
  • The lone pair, however, also reveals a significantly less fundamental character.

Is P2H4 electrolyte?

When an electrolyte is dissolved in water, almost all of its ionisation takes place. Let us determine whether or not  P2H4 is an electrolyte.

P2H4 is not an electrolyte because it does not separate into ions.

P2H4 + H2 → 2 PH3

Is P2H4 salt?

When a potent acid and base combine, salt is produced. Let us look a little more into the P2H4 lewis structure.

P2H4 is not a salt molecule because it requires complete ion dissociation. If a molecule doesn’t have both positive and negative ions, it can not dissociate. Therefore not behave salt.

Is P2H4 ionic or covalent?

By sharing electrons, two atoms can form covalent bonds. Let us examine the idea that  P2H4 is covalent or not.

P2H4 is a covalent compound rather than ionic. Since they are inorganic compounds and both atoms need to gain electrons. This is due to the presence of a covalent connection between phosphorous and hydrogen atoms. Phosphorous and hydrogen have nearly similar oxidation numbers. 


The P2H4 molecule possesses 14 valence electrons, of which two pairs of electrons and five bond pairs are present. Lewis structure of P2H4 with hybridised Sp3 molecule. Calcium monophosphide also referred to as the Ca2+ derivative of P24- is hydrolyzed to produce diphosphine(P2H4).


Monika Saini

Hi....I am Monika. I have done Masters in Chemistry. I am a Subject Matter Expert in Chemistry. I would say that I am a very passionate writer. The main goal of my writing is to present new perspectives. I want to discover new things that I can apply to my surroundings. Let's connect through LinkedIn-https://www.linkedin.com/in/monadbscr171291

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