Na2O Lewis Structure& Characteristics: 17 Complete Facts

Na₂O or sodium oxide is a basic oxide of an alkali metal with an ionic property having a molecular weight of 61.97 g/mol. Let us discuss more details about Na₂O.

The lattice structure of sodium oxide is antifluorite which is shown by crystallography study . When each Na ion is tetrahedrally coordinated to four oxide ions and each oxide ion is cubically coordinated by eight Na ions. The valency of the ions is satisfied and can form the base with water.

Two Na atoms are present at the terminal position and O is present at the central in Na₂O. there are two single bond present and two pairs of lone pairs over the O atom only. We can explore more about Na₂O bonding, lewis structure, hybridization, and other important facts in detail in the following sections.

1.      How to draw Na₂O lewis structure?

Lewis structure of every covalent molecule can find out nonbonding electrons and other molecular properties. Now we try to draw the Na2O lewis structure in a few steps.

Counting the valence electrons

Counting the valence electrons should give a clear idea of how many bonds will be present within the molecule or the number of non-bonded electrons present. The total number of valence electrons for Na₂O is 8, where 6 electrons come from the O site (group 16^th) and one electron comes from each Na atom.

Choosing the central atom

Based on electronegativity and size, we have chosen one atom as the central atom in a molecule. The central atom can decide the bond angle, reaction center, etc of a molecule, so it is an important step in lewis structure drawing. O is the central atom here because its size of it is larger than Na.

Satisfying the octet

As per octet Na or any s block element needs two electrons in their valence shell and O or other p block element needs eight electrons. So, the total electrons needed for satisfying the octet formed a stable bond 2+2+8 =12. The remaining electrons for the octet are accumulated by the suitable number of bonds.

Satisfying the valency

O is di valent and Na is monovalent. So, O can form two bonds where Na can form one bond respectively. The extra electrons satisfying the octet 12-8 =4 are accumulated by 4/2 = 2 bonds. These two bonds are made by O and two Na atoms to fulfill their valency and make a stable bond via sharing electrons.

Assign the lone pairs

The nonbonded electrons after satisfying the valency by making a suitable number of bonds are assigned as lone pairs over the O atom. Because O has more valence electrons than its bonding electrons and is also higher than its valency. Na has only one electron which is shared in a bond and lacks lone pair.

2.      Na₂O valence electrons

The electrons present in the outermost orbital of every atom are called valence electrons and participate in bonds. Let’s calculate the valence electrons for Na₂O.

The total valence electrons of Na₂O are 8. O contribute six because it is group 16^th element and each Na atom contributes 1 electron as it is group IA element. So, we add them together to get the total number of valence electrons for the molecule.

• Let us calculate the total valence electrons for Na₂O
• The valence electrons for O are 6
• The valence electron for each Na is 1
• So, the total valence electrons for Na₂O = 1+1+6 = 8 (as two Na atoms are present).

3.      Na₂O lewis structure lone pairs

The lone pairs are the non-bonded electrons present in the outermost shell they are the remaining valence electrons. Now calculate the lone pairs of Na₂O.

The total lone pairs of the Na₂O are four and the value is from the O site. O contains six valence electrons from its electronic configuration and only two of them are used in the bond formation. So, the remaining four electrons exist as two pairs of lone pairs over O and both Na has no lone pairs.

• Now calculate the total lone pairs of the Na₂o molecule by the formula, non-bonded electrons = valence electrons – bonded electrons.
• The lone pairs over the O atom are, 6-2 = 4
• The lone pairs over Na atom are, 1-1 = 0
• So, the lone pairs contribute from O only and the number are 4.

4.      Na₂O lewis structure octet rule

With the help of an octet, we can predict the stable valency of each atom in a bond formation by completing the valence shell. Let us understand the octet of Na₂O.

Na₂O obey octet by satisfied by its valency. The stable valency of Na and O are 2 and 1 respectively. Because O has six electrons in its valence shell and it needs two more electrons to complete its octet and again Na has only one electron and needs one more electron to complete the octet.

O atom forms two single bonds with two Na atoms for satisfying its stable di valency, where each Na atom forms one single bond because of its mono valency. By sharing electrons through the bond formation O as well Na completes their valence orbital and also completes the octet too.

5.      Na₂O lewis structure shape

The shape of the molecule is dependent on the central atom and the presence of any kind of repulsion with surrounding atoms. Let us predict the shape of Na₂O.

The molecular shape of the Na₂O is bent concerning central O which is confirmed by the following table.

The shape and geometry are not the same for the Na₂O molecule. According to the VSEPR (Valence Shell Electrons Pair Repulsion) theory, the AX₂E₂ type molecule adopts a bent shape instead of tetrahedral geometry. Because of repulsion between lone pairs and bond pairs change the shape from its ideal geometry.

6.      Na₂O bond 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 Na₂O in the next part.

The bond angle of Na₂O is less than 104⁰. Although its geometry is tetrahedral and the tetrahedral molecule is 109.5⁰ according to the VSEPR theory, due to lone pairs repulsion it decreases its bond angle to avoid repulsion. The shape is similar to a water molecule so the bond angle is the same as water.

• From the hybridization value, the bond angle can be calculated for Na₂O by bent’s rule.
• Actually, the bond angle is predicted by the bents rule of the hybridization formula, COSθ = s/(s-1).
• The hybridization of O₂ is sp³, so s character is 1/4^th.
• So, the bond angle is, COSθ = {(1/4)} / {1-(1/4)} = -.33
• Θ = COS^-1(-.33) = 109.5⁰
• But due to repulsion bond angle decreases to 104⁰

7.      Na₂O 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 Na₂O.

The formal charge of Na₂O is zero because it is a neutral molecule. Neither O nor Na carries any kind of charge over them. The di valency of Oxide is fully satisfied by the mono valency of Na+ electrically so no chance of charge present in the molecule. There is two single bond present and no charge appeared.

• 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 O atom is 6-4-(4/2) = 0
• The formal charge over each Na atom is 1-0-(2/2) = 0
• So, the overall formal charge over the Na₂O molecule is zero.

8.      Na₂O lewis structure resonance

Delocalization of electron clouds in between two or many skeletonic forms of molecules, those skeletons are known as Resonance. Let’s explore the resonance of Na₂O.

There is no resonance observed in the Na₂O because no excess electron density is present in the molecule. O is more electronegative so it cannot release electron density easily to the Na and for this reason, there is no chance of delocalization of electron clouds. No chance of forming skeleton forms.

O and Na both are satisfied by their valency so no chance of forming multiple bonds. Because of the absence of multiple bonds, there is no chance of delocalization of π electron density. So, no resonating structures are observed in the Na₂O molecule.

9. Na₂O hybridization

Mixing atomic orbitals to get a new hybrid orbital of equivalent energy is known as hybridization for formation of covalent bond. Let us find the hybridization of Na₂O.

The hybridization of Na₂O is sp³ which can be shown 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 O is, ½(6+2+0+0) = 3 (sp³)
• One s orbital and three p orbitals of O are involved in the hybridization.
• The lone pairs of O are also included in the hybridization.

10. Is Na₂O a solid?

When a molecule has strong interaction between its atoms and is held by strong force then exists as a solid form with low entropy. Let’s see whether Na₂O is solid or not.

Na₂O is a white crystalline solid molecule. It is held by strong ionic force so the atoms are tightly packed in an antifluorite lattice structure. At room temperature, each Na atoms are tetra coordinatively surrounded by the four O atoms, and each O is cubically surrounded by eight Na atom in the lattice.

Why and how Na₂O is solid?

Na₂O is solid because the atoms are present very closely and held by strong ionic force. There is strong van der Waal’s force of interaction are worked. Na₂O is a white solid crystal. The color of the molecule is for the interaction of atoms in the lattice crystal and at room temperature, it exists as a solid.

11. Is Na₂O soluble in water?

The solubility of water is dependent on the temperature and the nature of the solute which is polar or non-polar. Let’s see whether Na₂O is soluble in water or not.

Na₂O is not soluble in water rather it reacts with water with explosion and forms the NaOH as a product. When an oxide reacts with water and formed a base then it is known as basic oxide and Na₂O does the same and so it is basic oxide. For this reason, it remains insoluble under any physical conditions.

Why and how Na₂O is not soluble in water?

Na₂O is insoluble in water because when it gets dissolved in water it reacts with water and formed NaOH as a product. This reaction occurred via explosion because Li metal explosively reacts with water. So, it is unable to say that it cannot be soluble in water rather it reacts with water.

12. Is Na₂O 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 Na₂O is a molecular compound or not.

Na₂O is a molecular compound. The valency of Na and O are fully satisfied and the ratio of mixing of two atoms is fixed always. Because if the ratio will be changed then the molecule no longer will be Na2O and become NaO. That is a different molecule with different characters.

Why and how Na₂O is a molecular compound?

Na₂O is a solid molecular compound because the bi valency of O atoms and mono valency of Na atoms are fully satisfied here. Also, the ratio of Na and O is always 2:1 and it is fixed for the Na₂o molecule. So, for this reason, it is a molecular compound held by ionic force.

13. Is Na₂O an 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 Na₂O is acid or base.

Na₂O is neither acid nor a base rather it is a basic oxide. In the Na₂O, the oxide anion is very strong and it readily reacts with proton H atom to form strong OH^– and makes a strong base. When Na₂o reacts with water then the oxide of Na₂O reacts with the proton of water and formed a strong base like NaOH.

when it reacts with water or any proton-containing species then the oxide anion of Na₂O reacts vigorously with that proton and makes a strong base.

14. Is Na₂O an electrolyte?

Electrolytes are those substances that can be ionized when gets dissolved in water and carries electricity by solution. Let’s see whether Na₂O is an electrolyte or not.

Na₂O acts as an electrolyte when it gets dissolved in water. After dissolved in the water there will be ionic separation occurred between Na⁺ and O^2-. Although this process is very explosive so we cannot predict the mechanism.

Na²O is a strong electrolyte because when it is dissolved in water and breaks the bond to generate Na⁺ and this cation has higher mobility. So, it can conduct electricity through the solution very faster way.

15. Is Na₂O a salt?

The definition of salt is forming cations other than H⁺ and anions other than OH^– and bonded by ionic interactions when ionized. Let’s check whether Na₂O is salt or not.

Na₂o is a salt rather it is an oxide and more particularly basic oxide which can form a base that reacts with water. There is the absence of H⁺ and OH^– but the presence of other cations and anions, which is a sign of being salt. Also, there are ionic interactions present between two ions.

16. Is Na₂O polar or nonpolar?

The polarity of a molecule is depending on the presence of dipole-moment and electronegativity differences between two atoms. Let’s explore the polarity of Na₂O.

Na₂O is a polar molecule because a resultant dipole-moment is present. The bond present between Na and O is more polar in character. Also, there is a huge electronegativity difference between Na⁺ and O^2-. The shape of the molecule is asymmetric so there is no chance of canceling dipole moment.

The dipole moment will flow from the electropositive Na to the electronegative O atom.

17. Is Na₂O 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 Na₂O is covalent or ionic.

Na₂O is an ionic molecule and the main reason is Na and o are held by ionic force. Also, the charge density of Na⁺ is very high and its size is small so it can easily polarize the oxide anion. So it has most of the ionic character.

Why and how Na₂O is ionic?

Na₂O is ionic because the bond is formed between them by total donation of Na and accepted by the O atom. There is no share of electrons when a bond is formed. Again, as per Fajan’s rule, the higher ionic potential Na⁺ easily polarizes the oxide anion and makes the molecule ionic in nature.

Conclusion

Na₂O is an alkali basic oxide. It reacts with water to form a strong base, NaOH. It is a pure ionic solid crystalline molecule. It adopts anti fluorite structure in the lattice form.

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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.