Ca3N2 Lewis Structure & Characteristics: 17 Complete Facts

Calcium nitride or Ca₃N₂ is an inorganic solid molecule having a molecular weight of 142.248 g/mol. Let’s discuss Ca₃N₂ in detail in this article with an explanation.

Three Ca atoms satisfy the valency of two N atoms and vice versa. Here the bi valency of Ca and tri valency of N are fully satisfied by the suitable number of bonds. The central atom N is sp² hybridized here along with double bond and lone pairs and each N atom is connected with two Ca atoms respectively.

The geometry of the molecule is trigonal planar for both N atoms separately. Even the bond angle for both N atoms is the same because their environment is also the same. In the following section, let us explain lewis structure, hybridization, and polarity of Ca₃N₂ with proper explanation.

1.      How to draw the Ca₃N₂ lewis structure?

When we try to find out some important properties of a compound, it is the best way to draw its lewis structure. Let’s draw the Ca₃N₂ lewis structure in the next part.

Counting the valence electrons

The total valence electrons should be counted first when we draw a lewis structure. It is the number of summation of constituent atoms. The valence electrons of Ca₃N₂ are 16, where each N contributes 5 electrons and 2 electrons for each Ca. Because those number of electrons are available in the valence shell.

Choosing the central atom

In the 2^nd step, we should select one atom as a central atom, because concerning the central atom all the surrounding atoms are connected through bonds. Now based on size and electronegativity N is chosen as the central atom here. Both N has the same moiety so both are central atoms.

Satisfying the octet

Now we should connect each atom through the bonds by satisfying the octet of each atom. As per octet, we should try to complete the valence shell of each atom by two electrons and eight electrons respectively. So, as per octet total electrons needed are [(2*3) + (8*2)] = 22, those are accumulated by bonds.

Satisfying the valency

Each atom has a specific number of valencies on the availability of the electrons in the valence shell. The stable valency of Ca and N are 2 and 3 respectively. After completing the octet by [(22-16) = 6/2] = 3 bonds between five atoms, those valencies are satisfied by both atoms.

2.      Ca₃N₂ valence electrons

Those electrons are referred to as valence electrons which are present in the outermost orbital of respective atoms. Let us count the valence electrons for Ca₃N₂.

The total number of valence electrons of Ca₃N₂ was calculated at 16. Those electrons are the summation of valence electrons of three Ca atoms and two N atoms, so a molecule’s valence electrons will be the sum of the valence electrons of constituent atoms.

Count the total valence electrons for Ca₃N₂ as below

• The valence electron for the Ca atom is 2
• The valence electrons for N are 5
• The total valence electrons for Ca₃N₂ are (2*3) + (5*2) = 16

3.      Ca₃N₂ lewis structure lone pairs

Lone pairs are the valence electrons also but they are not involved in the bond formation they exist as non-bonded. Let us find out the lone pairs of Ca₃N₂.

Total lone pair for the Ca₃N₂ are 4. N has more valence electrons including non-bonded electrons. It has two non-bonded electrons after the formation of the suitable number of bonds. But in the case of Ca, all the valence electrons are involved in bond formation so it lacks lone pairs.

• Now we check the valence electrons for Ca₃N₂ in detail by the formula, Lone pairs = valence electrons – bonded electron.
• The lone pairs over the Ca atom is 2-2 = 0
• The lone pairs over the N atom are 5-3 = 2
• So, the total number of lone pairs of the Ca₃N₂ molecule will be 2*2 = 4 (as two N atoms are present).

4.      Ca₃N₂ lewis structure octet rule

Octet is the completion of the valence orbital by accepting a suitable number of electrons or sharing electrons. Let us discuss the Ca₃N₂ octet in detail.

The octet of Ca₃N₂ is completed via satisfying their valency separately. The electronic configuration of Ca and N are [Ar]4s² and [He]3s²3p³. So, the valence s orbital of Ca is already filled and when it donates two electrons its configuration is the same as a noble gas and its stable valency will be two.

Again, when N accepts three electrons, it can complete its valence p orbital by six electrons and already has two electrons in its s orbital, so N completes the octet via eight electrons. The stable valency of N is three which can also be satisfied by the donation of electrons from the p orbital.

5.      Ca₃N₂ lewis structure shape

The molecular shape is the particular shape that is arranged by the constituent atoms of that molecule by proper orientation. Let us predict the shape of Ca₃N₂.

The lewis structure shape of the Ca₃N₂ is bent around each N atom which can be confirmed from the following table.

From the above diagram, it is clear that Ca₃N₂ is an AX₂E type of molecule and as per VSEPR (Valence Shell Electrons Pair Repulsion) theory, it is shown that any AX₂E type of molecule adopts a bent shape instead of trigonal planar geometry. Because the shape cannot predict including the lone pairs.

6.      Ca₃N₂ lewis structure angle

A bond angle is that perfect angle that makes by the constituent atoms of a molecule for proper orientation. Let us find out the bond angle of Ca₃N₂.

The bond angle value of the Ca₃N₂ is around 104⁰. It is quite similar to bond angle with water because both have the same shape. The ideal bond angle for trigonal planar will be 120⁰ but when the molecule changes its geometry to bent, the molecule will be contracted and the bond angle will be decreased.

• The bond angle is now predicted from the hybridization value of the central atom.
• The bond angle formula according to Bent’s rule is COSθ = s/(s-1).
• The central atom N is sp² hybridized, so the s character here is 1/3^rd
• So, the bond angle is, COSθ = {(1/3)} / {(1/3)-1} =-( ½)
• Θ = COS^-1(-1/2) = 120⁰
• But here shape of the molecule has deviated so the bond angle is also changed from 120⁰ to 104⁰.

7.      Ca₃N₂ lewis structure formal charge

The formal charge is a concept that predicts the charge present within the molecule assuming the same electronegativity. Let us calculate the formal charge of Ca₃N₂.

The formal charge of the Ca₃N₂ is zero because it is a neutral molecule. The charge of three ca atoms is fully neutralized by the charge of two N atoms. The magnitude of change of N is greater than the Ca. also due to satisfaction of the valency of two atoms neutralized each other by the charge.

• The formal charge of the Ca₃N₂ can be calculated by the formula, F.C. = N_v – N_l.p. -1/2 N_b.p
• The formal charge accumulated by each Ca atom, 2-0-(4/2) = 0
• The formal charge accumulated by each N atom, 5-2-(6/2) = 0
• So, the overall formal charge by the three Ca atoms and two N atoms are, 0*2 + 0*3 = 0

8.      Ca₃N₂ lewis structure resonance

Delocalization of electrons cloud by different skeleton forms of the molecules is known as resonance. Let us explore the resonance of Ca₃N₂.

There are two double bonds and lone pairs present within the molecule, so it shows different resonating structures via delocalization of the π electron clouds. There is the excess electron density present over the N atom as lone pairs and it can undergo resonance with the consecutive double bonds.

The above three are the different skeleton forms of the Ca₃N₂. Among the three structure I is the most contributing structure because it has more stability. Structure I contains more covalent bonds after that structure II is the 2nd contributing structure because it has a lower number of covalent bonds.

9.      Ca₃N₂ hybridization

Atomic orbitals of different energy cannot make a bond so they undergo hybridization to form an equivalent hybrid orbital. Let us learn about the hybridization of Ca₃N₂.

The hybridization of central N in Ca₃N₂ is sp² which can be predicted from the following table.

• We can calculate the hybridization by the convention formula, H = 0.5(V+M-C+A),
• So, the hybridization of central N is, ½(5+1+0+0) = 3 (sp²)
• One s orbital and two p orbitals of N are involved in the hybridization.
• The lone pairs of N are also included in the hybridization.

10. Is Ca₃N₂ solid?

The definition of the solid molecule is that at room temperature the lattice energy is very high and atoms are closely packed. Let us see whether Ca₃N₂ is solid or not.

Ca₃N₂ is closely packed in the physical state and exists as a solid form. Because there is two double bond present within the molecule so the bond interactions are very strong here and all atoms are closely present. Each atom is present near another. There will be also strong covalent interaction present.

Ca₃N₂ is solid because van der Waal’s interaction between substituent atoms is very high for this reason all atoms are present in close proximity to one another at room temperature.

11. Is Ca₃N₂ soluble in water?

 The solubility in water depends on the nature of the bonding of the molecule and also the temperature applied. Let us see whether Ca₃N₂ is soluble in water or not.

Ca₃N₂ is soluble because it easily gets dissociated in water and breaks its bond. The polarity nature is also responsible for solubility. Also, there is less part of hydrophobic part present that increases water solubility.

Also water and Ca₃N₂ both are polar, so Ca₃N₂ soluble in water (like dissolve like).

12. Is Ca₃N₂ polar or nonpolar?

The polarity of a molecule depends on the presence of a permanent dipole moment, it indicates the direction of the dipole moment. Let us see whether Ca₃N₂ is polar or not.

Ca₃N₂ is polar and it has permanent dipole-moment present between Ca to N. Ca is electropositive so the dipole moment flows from the itself to electronegative N site. The electronegativity difference between two atoms is more than 0.4D so there will be a dipole-moment existing.

Why and how Ca₃N₂ is polar?

Ca₃N₂ is polar because the asymmetric structure of the molecule is the main reason. The shape of the molecule is bent so when dipole-moment flows from electropositive Ca to electronegative N then it cannot be canceled out by the same amount of dipole-moment because the direction is not opposite.

13. Is Ca₃N₂ a molecular compound?

The substance is called compound when two or more atoms make a perfect bond with satisfying the valency of the atoms. Let check if Ca3N2 is a molecular compound or not.

Ca₃N₂ is a molecular compound because all the valency of the substituents atoms is fully satisfied here. The stable valency of Ca is two and for N stable valency is 3. Here the proportion of the atom is 3: 2 for Ca and N because of the satisfaction of their valency

14. Is Ca₃N₂ acid or base?

According to the Arrhenius theory if a molecule releases H⁺ or OH^– in an aqueous solution then it will be called acid or base. Let see whether Ca₃N₂ is acid or base.

Ca₃N₂ neither be acid nor be base as per Arrhenius’s theory because in the aqueous solution, Ca₃N₂ cannot release H⁺ or OH^– because those ions are absent in the molecules. But it can be categorized as lewis acid because it can donate electron density towards the electron-poor center and acts as lewis acid.

Why and how does Ca₃N₂ act as lewis acid?

Ca₃N₂ can acts as lewis acid because each N has one lone pair and that lone pair can be donated because they are no longer present in the s orbital of N rather they are present in one of the hybrid orbitals. A hybrid orbital has less electronegativity than a pure s orbital so donation occurred easily.

15. Is Ca₃N₂ electrolyte?

On electrolysis of a molecule in solution and break into ions and those ions carry charge through the solution. Let check whether Ca₃N₂ is an electrolyte or not.

Ca₃N₂ behaves as an electrolyte on electrolysis of Ca₃N₂ occurred then the molecule breaks into two different ions, one is Ca²⁺ and the other N^–. Ca²⁺ ions are deposited in the anode whereas N^– is deposited in the cathode. So those ions make the solution charged because they are charged particles.

Why and how Ca₃N₂ is a strong electrolyte?

Ca₃N₂ behaves as a strong electrolyte because on the electrolysis Ca²⁺ is formed as the cation. The charge density of Ca²⁺ is very high and also its mobility is very fast so it can carry electricity through the solution in a very faster way, again N^– is a stronger anion due to higher electronegativity.

16. Is Ca₃N₂ salt?

Salt is formed by a cation other than H⁺ and anion other than OH^– and there is an ionic interaction occurred between them. Let us see if Ca₃N₂ is a salt or not.

Ca₃N₂ can be thought of as salt because it is formed by Ca²⁺ and N^– which are other than H⁺ and OH^– ions. Also, there is some kind of ionic interaction occurred between two strong positive and negative charges. Also, salt carried electricity on electrolysis, being a electrolyte it can carry electricity.

17. Is Ca₃N₂ ionic or covalent?

Every covalent molecule has some % of ionic character or vice versa – Fajan’s rule of polarizability. Let see whether Ca₃N₂ is ionic or covalent.

Ca₃N₂ is a covalent molecule which is formed by the hybridization of the central N atom, which is sp². A covalent molecule always shows hybridization. But there is some kind of ionic interaction present between Ca²⁺ and N^–, so it has some % of ionic character.

Ca₃N₂ is ionic because the Ca²⁺ has a higher charge potential and it can polarize the anion. Again, the size of the N^– ion is larger due to the extra electron, so it has higher polarizability and can be polarized by the cation, and showing ionic character.

Conclusion

Ca₃N₂ is an ionic molecule so it can act as salt. It is a strong electrolyte also. The lone pairs of N can be donated to any reaction center to participate in various chemical reactions and make the molecule reactive. But the presence of a double bond makes the molecule stable also.

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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.