P2O5 Lewis Structure & Characteristics(15 Important Facts)

P2O5 (Phosphorus pentoxide) is a nonmetal oxide in which two phosphorus atoms are connected by five oxygen atoms. Let us look at some details regarding P2O5

P2O5 has a molecular weight of 283.9 g/mol. It has a 2.30 g/cm3 density. If heated more quickly, it can sublimate at 423 °C at air pressure. With phosphorus atoms, all other oxygen atoms have formed double bonds. P2O5 appears white monoclinic powdered or as a crystal.

Let us provides a detailed description of P2O5 lewis structure, shape, valence electrons, hybridisation, and more below.

How to draw P2O5 lewis structure?

A Lewis electron dot structure describes all the bonds in a molecule, including the remaining lone pairs between the bonding atoms. Here is the process for drawing the P2O5 Lewis structure.

The total number of electrons in P2O5 valence shells:

P2O5 is composed of phosphorus (P) and oxygen (O). The outermost shell of the periodic table group 15 element P has five electrons. O is in group 16 of the periodic table and has six electrons in its outermost shell. 5*2 + 6*5 = 40 is the total number of valence electrons.

Selection of central atom:

The centre atom of P2O5 should be the phosphorus atom. When the electronegativity values of phosphorus (P) and oxygen (O) are compared, the phosphorus atom is found to be less electronegative. Thus, two phosphorous atoms fill the two middle positions and five oxygen atoms surround the phosphorous.

Place lone pairs (remaining valence electrons) and, if necessary, form a covalent bond:

  • Total valance electrons pairs = sigma bonds + pie bonds + valence shell lone pairs.
  • There are a total of 20 electron pairs to identify as bonds and lone pairs.
  • There are now only fourteen (20-6=14) lone pairs remaining to mark on atoms.
  • The remaining electron pairs should be used to make marks on the outside of atoms.
  • Three lone pairs will be taken by four outside oxygen atoms.
  • Twelve electron pairs were now labelled as lone pairs on the outside of oxygen atoms.
  • The two lone pairs on the centre oxygen atom.

If there are charges, mark them on the atoms:

Each atom contains charges. Each outside oxygen atom is negatively charged, while each phosphorus atom is positively charged. It is critical to mark those charges to be the most stable. So we calculate the formal charge for a stable structure.

The final structure of P2O5:

When atoms have the fewest charges, the structure is very stable. Because most atoms in the P2O5 structure have charges, the structure is very unstable. As a result, we can gradually reduce atom charges by converting lone pairs to bonds and the final structure is as shown below:

p2o5 lewis structure
P2O5 lewis structure

P2O5 lewis structure formal charge

Molecules have a charge that reflects their electron count when compared to isolated neutral atoms. Let us calculate the formal in P2O5.

P2O5 has zero formal charges. To determine the formal charge of a P2O5 molecule, use the following formula: Formal charge = Valence electrons in P2O5 – Lone pair electrons in P2O5 – ½ Bonded pair electrons in P2O5.

The Formal charge table on P2O5 is shown below:

Atoms involved
in P2O5
Lone pair
Central Atom
5 0 10/2 (5-0-10/2)
Outer Atom
6 4 4/2 (6-4-4/2)
The formal charge on P2O5 lewis structure, P = 0, O=0, P2O5 =0

P2O5 valence electrons

The valence electrons are electrons that are found in an atom’s outermost orbit. Let us find the valence electrons in P2O5.

P2O5 Lewis structure contains a total of 10 + 30 = 40 valence electrons. The periodic table is important here because phosphorous is in group 15 and oxygen is in group 16. They each have five and six valence electrons.

  • P has valence electrons 2*5=10.
  • O has valence electron= 5*6.
  • The total number of valence electrons in P2O5 is 10+ (5*6)=40.

P2O5 lewis structure octet rule

The octet rule is an atom is most stable when its valence shell has eight electrons. Let us check whether P2O5 satisfied the octet rule or not.

P2O5 satisfied the octet rule by using valence electrons. Only 14 lone pairs remain to be marked on atoms. Three lone pairs are placed on four oxygen atoms (outside) to complete their octet.

Two lone pairs are placed on one oxygen atom (inside) between two phosphorous). Each oxygen atom in this system completed its octet configuration.

P2O5 lewis structure lone pairs

Lone pair electrons are unshared electrons that remain in a chemical or molecule after forming a bond. Let us look at the P2O5 lone pair electron.

P2O5 has a total of 20 lone pairs on the oxygen atoms. Two phosphorous atoms in the P2O5 molecule have no lone pair, while five oxygen atoms each have two lone pairs. The P2O5 molecule has 20 lone pairs and 6 bond pairs.

P2O5 lewis structure shape

Structures are created and put together, whereas objects are moulded by their spatial contours. Let us study in detail the P2O5 structure.

The P2O5 molecule has a trigonal planar shape and geometry. As per VSEPR theory, the generic formula AXn (AX3). A stand-in AX3 for the core atom, Phosphorus act as the centre atom in the P2O5. X indicates the number of surrounding atoms and n stands for three.

  1. The molecular geometry and electron geometry of P2O5 =  Trigonal planar.
  2. It exists in polymorphism or more than one crystalline form. The metastable form, which is also known as the common form, is the most stable. 
  3. During the formation of a tetrahedron, two oxygen atoms donate their terminal electrons to opposing oxygen-phosphorus bonds, forming a terminal P=O bond.
  4. Due to its 143 pm P=O bond length, its P-O sigma bond length is 160 pm.
  5. Below is the image that explains its structure:
p2o5 lewis structure
Structure of P2O5 from Wikimedia

P2O5 lewis structure angle

A geometric angle formed by two adjacent bonds is known as a bond angle. Let us discuss the bond angle of the P2O5 molecule.

P2O5 features two bond angles a 102° O-P-O bond angle and a 123° P-O-P bond angle. This is because Van der Waals forces act as the bonds that hold its molecules together. Below is an image of the bond angle:

p2o5 lewis structure
The bond angle of P2O5

P2O5 hybridization

Similar energy levels can interact to create new, dissipative orbitals that have less energy but are more stable. Let us calculate the hybridization in P2O5.

P2O5 has sp2 hybridization in its lewis structure. The hybridization is computed using the formula of steric number: The steric number in the P2O5 molecule = The central P atom having lone pair + The central P atom having three bonded atoms (each of three oxygen).

  • The steric number, in this case, is 0+3 = 3.
  • The steric number is three, indicating sp2 hybridization.

Is P2O5 solid or liquid?

Known mass and volume, tight packing, and specific mass and volume define the shape of solids. Let us talk about whether P2O5 is solid or not.

P2O5 (phosphorous pentaoxide) is a solid rather than a liquid substance. The substance is white and crystalline. Several forms of this substance exist, but it is most often identified by the empirical formula P2O5.

  • This is due to the presence of several amorphous or glassy solids as well as four recognised crystalline polymorphs.
  • The most stable form of P2O5 is the hexagonal or alpha modification.
  • This form is composed of P4O10 molecules.

Is P2O5 soluble in water?

It is known as solubility that how well a chemical substance can dissolve in a solvent, such as water. Let us look at how soluble P2O5 is in water.

P2O5 is soluble in water and most of the time produces Phosphoric acids. It has a strong affinity for water and extracts water from inorganic and organic compounds. This makes it a highly effective dehydrating component.

Why P2O5 is soluble in water?

P2O5 is soluble in water because of producing different acids with different stoichiometry. The reaction is as follows:

  • If the reaction involves a 1mole of water it produced Metaphosphoric acid,

                     P2O5 + H2O —-> 2 HPO3.

  • If the reaction is with 2 moles of water it produced Paraphosphoric acid,

                      P2O5 + 2 H2O —-> H4P2O7

  • If there are 3 moles of water involved in the reaction, Orthophosphoric acid is produced,

                      P2O5  + 3 H2O —-> 2 H3PO4

Is P2O5 polar or nonpolar?

The electronegativity, electron dispersion, and dipole moment of a molecule must be understood to comprehend its polarity. Let us talk about P2O5 polar or nonpolar.

P2O5 lewis structure is polar. This is according to the Pauling scale, if an atom’s electronegativity differs from another by more than 0.5, that atom will behave polarly.

  • The electronegativity of phosphorus is 2.19 is lower than that of oxygen has 3.44. 
  • As a result, oxygen has a stronger propensity to draw an electron to itself.
  • The electronegativity difference between phosphorus and oxygen is greater than (3.44 – 2.19 = 1.5).

Why P2O5 is polar?

P2O5 produces highly polar materials because some dipole moments are present in molecules as a result of variations in electronegativity. The polar nature also depends upon two factors:

  • Dipole moment 
  • Molecular Geometry

Is P2O5 molecular compound?

Chemically compounded substances fall under the category of pure material is molecular. Let us determine whether or not P2O5 is a molecule.

P2O5 is a molecular compound. It is molecular due to the gravitational pull an element exerts and the electrons it shares in a bond with other elements are measured by its electromagnetic value. 

Is P2O5 acid or base?

The type of element that forms oxides determines the type of oxides that form. Let us find out whether P2O5 is acid or base.

P2O5 is acid rather than base. It is an acidic substance that when combined with water yields phosphoric acid. Its oxidation state is extremely high in phosphorus pentoxide. The stated acid will be produced through an exothermic reaction with water.

P2O5 + 3 H2O → 2 H3PO4 

These molecules produce their oxoanions and H+ when they interact with water as in the reaction below:

  • SO3 +H2O  → SO42- + 2 H+
  • P2O5 + 3 H2O→ 2PO3-4 + 6 H+

Is P2O5 electrolyte?

Water or other chemicals dissolve electrolytes, which conduct electricity when dissolved. Let us find out whether P2O5 is an electrolyte or not.

P2O5 is not an electrolyte individually due to a nonmetal oxide and dimer form. It is because they are situated on the same sides of the Periodic table. The combination of electrolytes in the systems is only possible when it follows Li2O-B2O3-P2O5 (lithium-based glass electrolyte).

Is P2O5 salt?

The chemical compound salt is composed of cations and anions, although it has no net charge. Let us determine whether P2O5 is salt or not.

P2O5 is not salt. It is an acidic compound in water. It does not behave as salt because the outermost electrons become shared in covalent connections between both nuclei because of the relatively small difference in size between P and O

Is P2O5 ionic or covalent?

A covalent link between two nonmetallic elements is a common indicator that a molecule is covalent. Let us find P2O5 is ionic or covalent.

P2O5 is a covalent rather than ionic compound. The molecule is polar covalent due to being found in non-metal oxides like SO3. It is covalent because the difference in electronegativity is greater than 1.4. The oxygen atoms exert a stronger attraction on the shared electrons than the phosphorus atoms.  


As P2O5 crystallizes, it has at least four polymorphs. It is a metastable form of P4O10 molecules that is most popular. P2O5 is a covalent polar molecule. It is a hygroscopic solid. P2O5 has a 102° bond angle.


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