PH4+ Lewis Structure & Characteristics: 17 Complete Facts

PH₄⁺ is a hydride of P having a molar mass of 35.006 g/mol, it is cationic for phosphorus pentahydrate. Let us explore more about this in this article.

The central P atom in the PH₄⁺ is sp³ hybridized with a tetrahedral shape. Due to that particular shape, the bond angle of the molecule is 109⁰. P is in a -3 oxidation state in this cation hydrate molecule. The positive charge is lie over the P atom only because it is not satisfied with its pentavalent here.

PH₄⁺ is a disproportionation form of PH₃ and PH₅. The oxidation state is intermediate in this molecule than the other two compounds. Let us discuss some important topics of PH4+ like lewis structure, hybridization, bond angle, and valence electrons with proper explanations in the following article.

1.      How to draw the PH₄⁺ lewis structure

Lewis’s structure of PH₄⁺ can give us a clear idea about the molecular property of PH₄⁺. Let us try to draw the lewis structure of PH4+ in different following steps.

Counting the valence electrons

Counting the valence electrons for a molecule is the first step to draw its lewis structure properly. Here the total valence electrons are 8. Now we can explain these valence electrons, by adding valence electrons of P as 5 and for four H atoms as 1 each, and 1 will be deducted for the positive charge present.

Choosing the central atom

Choosing the central atom for drawing the lewis structure is another important step. Here P is chosen as the central atom because of two reasons. The first reason is the size of P is larger than H so it can accumulate all the atoms surrounding itself and the second reason P is more electropositive than H.

Satisfying the octet

Always it should be checked while drawing lewis structure that every atom should obey the octet rule by completing their valence orbital either accept or share electrons from others. So, here P has four electrons due to positive charge and shares four electrons, and H shares one electron.

Satisfying the valency

To obey octet total electrons required for PH₄⁺ are 8+(4*2)=16 but total valence electrons are 8, so to satisfy the valency of each atom we should add ½(16-8)=4 bonds, but P is pentavalent so one positive charge present over it and mono-valency of each H atom also satisfied by sharing one bond with central P.

Assign the lone pairs

In the last step, we assign the non-bonded electrons over respective atoms. Those electrons are coming lastly after satisfying the octet as well as valency. P has five valence electrons and due to positive charge, it has now four electrons and all electrons are bonded. So, no lone pairs are observed.

2.      PH4+ lewis structure shape

Lewis structure shape is very particular for that molecule who has the same environment. Now we try to learn about the shape of PH₄⁺ in the following section.

The Shape of the PH₄⁺ is tetrahedral according to the following table.

PH₄⁺ has similar geometry to PH3 like tetrahedral. Because PH3 and PH₄⁺ have the same environment like both are tetra-coordinated molecules. For the PH3 it has one lone pair and for PH₄⁺ it has one extra bond pair instead of lone pairs. This geometry is confirmed according to the VSEPR theory.                                                                                                                                                     

3. PH4+ valence electrons

With the help of valence electrons, each atom can form a stable bond with another, and also the valency will be justified. Let us calculate the total valence electrons for PH₄⁺.

The total valence electrons of PH₄⁺ is 8 because 5 electrons come from P and for each H is 1, so for 4 H atoms the numbers are 4, and due to the presence of one positive charge, one will be deducted from the total value. So, valence electrons of PH₄⁺ are the summation of each atom.

• Let us calculate the total valence electrons for the system separately.
• The valence electrons for central P are 5
• The valence electrons for the surrounding H atom is 1
• Due to one positive charge electron deduction is 1
• So, total valence electrons for PH4+ are 5+(1*4)+1=8

4.      PH4+ lewis structure octet rule

To satisfy the valency of each atom they obey the octet after the bond formation via completing their valence orbital. Now discuss the octet about PH₄⁺ in detail.

P and H both completed octet in PH₄⁺ by sharing bonding. The stable valency of P is 5 confirmed from its electronic configuration [Ne]3s²3p³. So, it can form stable 5 bonds but here form only four bonds and for this reason, a positive charge appears on it to satisfy its octet. H also formed a single bond.

To obey the octet for p block P and s block H atom total need of electrons will be 8+(4*2) =16. But the valence electrons are 8, so the remaining electrons are accumulating by 8/2 = 4 bonds to satisfy their valency. P is pentavalent which is satisfied by four bonds and a positive charge to complete the octet.

5.      PH4+ lewis structure lone pairs

Lone pairs are those valence electrons that are not participating in the bond formation they are non-bonded electrons. Let us count the lone pairs of PH₄⁺.

PH4+ has no lone pairs over it. Because all the valence electrons of PH₄⁺ which comes from P and H are involved in the bond formation. Even P is positively charged which means it lacks valence electrons in its valence shell. H has only one electron, so there is no chance for lone pairs.

• Lone pairs are calculated by the following formula, non-bonded electrons = valence electrons – bonding electrons.
• The lone pair over P is, 4-4 = 0 (as P carries a positive charge)
• The lone pairs over H is, 1-1 = 0
• So, the total lone pairs of PH4+ are zero.

6.      PH₄⁺ lewis structure angle

A bond angle is that angle makes by the atoms which are present in a molecule for proper orientation and shape. Now calculate the bond angle of PH₄⁺ in the next part.

The bond angle of PH₄⁺ is 109.5⁰ because it is a tetrahedral molecule. The size of P is very large than H, so it can accumulate four H in the tetrahedral moiety without any steric repulsion. Also, no lone pairs are present over central P, so there is no chance that repulsion and bond angle has not deviated.

• Actually, the bond angle is predicted by the bents rule of hybridization, COSθ = s/(s-1).
• The hybridization of PH₄⁺ is sp³, so s character is 1/4^th.
• So, the bond angle is, COSθ = {(1/4)} / {1-(1/4)} = -0.333
• Θ = COS^-1(-.033) = 109.5⁰
• Which is the perfect bond angle for tetrahedral molecules like PH4+

7.      PH4+ lewis structure formal charge

With the concept of formal charge, we can predict the magnitude of charge and which atom accumulates that can be calculated. Let us calculate the formal charge for PH₄⁺.

The formal charge of PH₄⁺ is 1 because it has already a charge present over the molecule. H is monovalent, and if the charge is present over it, then there is no electron for H, which is impossible. But P is pentavalent and if the charge is present over it then it becomes tetravalent which is possible.

• Let us check the value of the formal charge present over H or P by the formula, F.C. = N_v – N_l.p. -1/2 N_b.p.
• The formal charge over the P atom is, 5-0-(8/2) = +1
• The formal charge the over H atom is, 1-0-(2/2) = 0
• So, from the above data, it is confirmed that the positive charge is present over P and the value is +1.

8.      PH4+ lewis structure resonance

Resonance is the delocalization of electron clouds through different skeleton forms of the molecule. Let’s see whether is possible for a PH₄⁺ resonating structure or not.

For the PH₄⁺ molecule, there is no resonating structure possible. Although it is a theoretical concept, resonance is only possible where extra electron clouds and π electron density are present. But in the PH₄⁺ there is no such case present also P is positively charged means it lacks electrons.

P and H are bonded with a sigma bond and the nature of electron flow is sigma electron, so there is no excess electron clouds present that can resonate from one to another. Also, p is positively charged so it holds the electron density very tightly and that electron density cannot be delocalized.

9.     PH₄⁺ hybridization

Hybridization is a theoretical concept by which the mixing of atomic orbitals forms a new hybrid orbital of equivalent energy. Let us predict the hybridization of PH₄⁺.

PH₄⁺ is sp³ hybridized which is confirmed in the following table.

• We can calculate the hybridization by the convention formula, H = 0.5(V+M-C+A),
• So, the hybridization of central P is, ½(5+4-1) = 4 (sp³)
• One s orbital and three p orbitals of P are involved in the hybridization.
• The positive charge is also included in the hybridization.

10. Is PH₄⁺ soluble in water?

The solubility in water for any substance must be dissolved by ionization and then gets soluble in water. Let us discuss the solubility of PH₄⁺ in water.

PH₄⁺ is practically insoluble in water. P cannot form a hydrogen bond with water. The size of P is larger and the electronegativity of P is also less so it is not compatible with hydrogen bonding. PH₄⁺ can be ionized in water easily as it carries a charge and but not soluble in water.

Why and how PH₄⁺ is not soluble in water?

PH₄⁺ is not soluble in water because it is a gaseous molecule and for a gaseous molecule the chance of solubility in an aqueous medium is very poor. Although it carries a positive charge and for this reason, it can attract water molecules. Again, due to no-polarity it does not soluble in water.

11. Is PH₄⁺ solid?

When atomic interactions in a molecule are very high like van der Waal’s or London force then the molecule exists as a solid. Let’s see whether PH₄⁺ is solid or not.

PH₄⁺ is not solid and it can exists as a gaseous form at room temperature. The bond interaction between P and H is very low. Both are non-metal classes, again H is a gaseous atom so solidified H at room temperature is not possible. So, the lattice energy between them is very poor.

Why and how PH₄⁺ is gaseous?

PH₄⁺ is gaseous because the bond between P and H is very weak and there are weak forces of interaction occurred. When a molecule exists in the gaseous form then its entropy will be increased and it is favorable in terms of thermodynamics. So, PH₄⁺ exists as gaseous rather than solid at room temperature.

12. Is PH₄⁺ a molecular compound?

When mixing two or more atoms in a fixed ratio maintaining the valency by a chemical reaction is known as the compound. Let’s see if PH₄⁺ is a molecular compound or not.

PH₄⁺ is formed by P and H maintaining the proper valency as well as a fixed ratio. If the ratio of P or H will be changed then it will no longer be PH₄⁺, it changes to other compounds having different properties. Also, PH₄⁺ is formed by a chemical reaction.

Why and how PH₄⁺ is a molecular compound?

PH₄⁺ is a molecular compound because it formed by a proper covalent bond between P and four H atoms by maintaining the fixed ratio of these two atoms. Here pentavalent of P is maintained by the four bond pair and a positive charge and monovalency of H are also satisfied. So, PH₄⁺ is a molecular compound.

13. Is PH₄⁺ acid or base?

The acidity or basicity of a molecule depends on the ability to donate H+ or OH- in an aqueous solution according to Arrheneius’s theory. Let’s see if PH₄⁺ is acid or base.

PH₄⁺ is an acid and it can donate H+ in an aqueous solution. The bond interaction between P and H is very weak so it can easily donate H+ ion and acts as an acid. Also, due to the positive charge, it can accept electron density rapidly and acts as lewis acid. From the pH value of PH₄⁺, it is a weak acid.

Why and howPH₄⁺ is lewis acid?

PH₄⁺ is a lewis acid because it can accept lone pairs or electron density from the suitable lewis base or electron-rich center. P has a vacant d orbital where it can accept the electron density and also due to positive charge the electron affinity of the P center increases results decreased in orbital energy.

14. Is PH₄⁺ electrolyte?

Electrolytes are that substance which can be ionized in the aqueous solution and carries electricity by this solution. Let’s see whether PH₄⁺ is an electrolyte or not.

PH₄⁺ is an electrolyte and it carries a charge over it. So, when it is dissolved in water solution and if not fully ionized although it can carry electricity by that solution. PH₄⁺ ionizes in an aqueous solution and forms one cation and this charged particle can carry electricity.

Why and how PH₄⁺ is an electrolyte?

PH₄⁺ is an electrolyte because it can easily be ionized when it gets dissolved in an aqueous solution. When it is ionized it formed a phosphine molecule which is a neutral molecule along with H+. the mobility of H+ is very high due to its small size and ionic potential, so it can carry electricity.

15. Is PH₄⁺ salt?

In chemistry, the definition of salt is forming cations other than H⁺ and anions other than OH^– and bonded by ionic interactions. Let’s check whether PH₄⁺ is salt or not.

PH₄⁺ is not a salt, the main reason is it cannot produce cation other than H⁺ and the second reason is it is not formed by the ionic interaction. It is a covalent molecule and forming by the electron share method. Already it behaves as acid, so it cannot be a salt anymore.

Why and how PH₄⁺ is not a salt?

PH₄⁺ is not a salt because it cannot produce a cation and anion other than H⁺ and OH^–. because when it is ionized it forms the neutral molecule PH3 along with H⁺. For this releasing H⁺ it already behaves as acid and when an acid molecule reacts with the base then the salt will be produced.

16. Is PH₄⁺ ionic or covalent?

As per Fajan’s rule, no molecule is cannot be 100% ionic, it has some character of covalent and vice versa. Let’s see if PH4+ is covalent or ionic.

PH₄⁺ is covalent and the main reason behind an ionic molecule is forming by the ionic interaction and total electrons donation method. But the PH₄⁺ molecule is formed by the share of electrons between P and H. Again, the ionic potential of H⁺ is not high and it cannot polarize its counterpart of the molecule.

Why and how PH₄⁺ is covalent?

PH₄⁺ is covalent because P is a nonmetal and always formed a bond by the sharing of an electron with others. Again, the P-H bond is not polar because there is no difference in electronegativity so, the bond is covalent in character. There is no chance of polarizing the anion by cation and polarizability.

17. Is PH₄⁺ polar or nonpolar?

The polarity of a molecule is depending on the presence of dipole-moment and electronegativity differences between two atoms. Lets us explore the polarity of PH₄⁺.

PH₄⁺ is a non-polar molecule and the electronegativity of P and H is almost the same and for this reason, there is no electronegativity difference. So, there is no flow of dipole-moment within the molecule although it is a asymmetric molecule.

Why and how PH₄⁺ is nonpolar?

PH₄⁺ is non-polar because the electronegativity is the same for both P and H atoms, so there is no origin of dipole-moment towards less electronegative atom. Generally, dipole-moment flows from a more electronegative substituent to less electronegative element, but here this case is not available.

Conclusion

PH₄⁺ is a gaseous molecule and cation of PH5 or it can be thought as PH3 accepted one more proton. It is a covalent and non-polar molecule, also it is not an electrolyte although carries a charge over it.

Also Read:

• Nocl lewis structure
• Brcl5 lewis structure
• Baso4 lewis structure
• Xeo3 lewis structure
• Ibr3 lewis structure
• Ocn lewis structure
• Asf5 lewis structure
• N2h4 lewis structure
• Hclo2 lewis structure
• Ch2i2 lewis structure

Biswarup Chandra Dey

Hi……I am Biswarup Chandra Dey, I have completed my Master’s in Chemistry from the Central University of Punjab. My area of specialization is Inorganic Chemistry. Chemistry is not all about reading line by line and memorizing, it is a concept to understand in an easy way and here I am sharing with you the concept about chemistry which I learn because knowledge is worth to share it.