Sodium Oxide (Na2O) - Oxide ion, Formation, Structure, Properties, FAQs

Q: What is the chemical formula of sodium oxide?

The chemical formula of sodium oxide is Na 2 O.

Q: What is the compound name and full form of Na2O?

The compound name or full form of Na 2 O is sodium oxide.

Q: Is Na2O ionic or covalent in nature?

Sodium oxide or Na 2 O is ionic in nature.

Q: What is the formula of sodium oxide?

The molecular formula of sodium oxide is Na 2 O.

Sodium Oxide (Na2O) - Oxide ion, Formation, Structure, Properties, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:45 PM IST

Sodium oxide as the name suggests is a chemical compound with chemical formula Na₂O. It has many applications in glass and ceramics industries. Sodium oxide is an alkali metal oxide and it is also a basic anhydride form of sodium hydro oxide, and is denoted by the symbol NaOH. In presence of air, sodium oxide burns with a white light which is very vivid but in existence of oxygen it burns even more rapidly as compared with air. After burning it forms a white powder look a like substance which is called sodium oxide. The molecular mass of sodium oxide is 61.97g/mol. Sodium oxide is a chemical compound which is yellow in color and the nature of sodium oxide is crystalline solid. Sodium oxide has a melting point of 1132^oC.

This Story also Contains

Formation of sodium oxide
Properties of sodium oxide
Structure of sodium oxide
Oxide ion
Applications of sodium oxide

Formation of sodium oxide

Sodium oxide is formed with the help of the reaction of sodium hydroxide with sodium which is in metallic in form. Instead of metallic sodium, sodium nitrate or with sodium peroxide, we can also produce sodium oxide. In this reaction, hydrogen is produced as a by-product. The chemical equation is given below

NaOH+ NaO→Na₂O+H₂

By thermal decomposition of sodium carbonate at the temperature of 850^oC, we can get sodium oxide along with by-product carbon dioxide.

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Sodium oxide with water

Sodium oxide is highly insoluble in water. Sodium oxide reacts vigorously in presence of water, giving sodium hydro oxide as the product. Thus, sodium oxide should not be kept in presence of water, it should be stored away in clean and dry environment, because of its inflammable nature.

Properties of sodium oxide

In presence or when exposed to water, sodium oxide changes into sodium hydroxide. The reaction of sodium oxide with water is very vigorous because of large exothermic activities taking place. Thus, sodium oxide should be stored in a clean and dry place, away from water. Alkali oxides like M₂O has applications in crystallization of the structure of antifluorite. Thus, the location of the anions and cations relatively gets backwards in comparison to the location of calcium difluoride. The cause of this process is due to ions of sodium that tetrahedrally coordinate with 4 oxides of ions and cubic oxides that co ordinate with Na ions which is 8 in number. Na is nothing but the chemical name of sodium metal. The full form of Na is sodium metal.

Structure of sodium oxide

The structure of sodium oxide comprises of molecules which are made up of one oxygen anion and two sodium cations. Therefore, sodium oxide has two sodium oxygen ionic bonds. The structure of sodium oxide is given below

Structure of sodium oxide

The Ph of Na₂O is almost 14 when dissolved in aqueous medium, making it complete basic in nature.

The Lewis structure of Na₂O is given below

The Lewis structure of Na2O

The ionic bonding diagram of sodium oxide is given below

The ionic bonding diagram of sodium oxide

Oxide ion

Oxide as the name suggests is the two anion of oxygen atom. Oxides of metal usually comprises of anion of oxygen atom in the oxidation state of -2. Metals are mostly oxidized in presence of oxygen in water or in the air. Even the so- called pure metals or metals which are considered of high grade often gets oxidize by developing a coating. With different concentration of oxygen being oxidized with the metal in presence, many metals can form multiple oxides. Examples of such metals are iron, carbon, nitrogen, silicone, titanium, and lithium. In the cases of these metals, the oxides are differentiated by specifying the number of atoms in the complex, as in carbon dioxide and carbon monoxide, or by giving priority to the oxidation number as in the case of iron oxides.

The formula of oxide ion is 0²-.

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Formation of oxide

Because of the electronegative nature of oxygen atom, it forms chemical bonds which are stable with all elements which give corresponding oxides. The most common tracks for corrosion or oxidation of metal are oxidation by oxygen and hydrolysis. The presence of addition of oxygen and water is most corrosive in nature. In the existence of oxygen and water, few elements namely sodium react vigorously to give hydroxides, thus alkali and alkaline earth metals are in the metallic form or native form, found in nature.

Cesium being the most reactive in nature has applications in vacuum tubes as a getter and aqueous medium of sodium and potassium are used in dehydration operations of organic solvents. The exterior of many metals comprises of hydroxides and oxides in the existence of air. In electrolytic anodizing, the oxide layer of Al can be constructed to thicker in concentration. Many metals in grandly grounded powder form are vigorously inflammable in presence of air. Oxides are differentiated into many types decided on the factors like nature and properties the compounds have, like acidic oxides, neutral oxides, basic oxides and amphoteric oxides etc.

Also, students can refer,

Applications of oxides

For practical experiments in laboratories, oxides are used for the formation of salts.
It has applications in production of slag.
Oxides has applications in the production of motor industries.
Oxides are also used as a drying agent.

Applications of sodium oxide

Due to its high solubility and thermal stability, sodium oxides have the best applications in ceramic, glass and optic manufacturing industries. Oxidized compounds are good conductors of electricity. Due to the solubility of sodium oxide, it is used in making clay apparatus, structural constituents of aeronautical industries which are light in weight, ceramic components and in electrical field. Due to the ability of sodium oxide of ionic conductance it has applications for manufacturing fuel cells.

Sodium oxides as the name suggest are anhydride in basic form which make it more suitable for reaction with acids. Sodium oxides are accessible in many forms like tablets, pellets, spluttering targets, pieces and non-powder. Sodium oxide is also used to make glazes, being an active flux to give color response. It is also used in structures as a primary deflocculant in casting slips. Sodium oxides are used in glass industries in cooperation of silicone and specific additives.

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NCERT Chemistry Notes:

Frequently Asked Questions (FAQs)

1. What is the chemical formula of sodium oxide?

The chemical formula of sodium oxide is Na₂O.

2. Is oxygen a cation or an anion?

Since oxygen does not carry a charge, it is neither a cation nor an anion.

3. What is the nature of sodium oxide, is it acidic or basic?

Sodium oxide, as the name suggests comprises of an oxide ion which has the ability to combine with a hydrogen -ions, makes the sodium oxide a very strong base.

4. Write the Na full form in chemistry.

Sodium is denoted as Na.

5. What is the compound name and full form of Na2O?

The compound name or full form of Na₂O is sodium oxide.

6. Is Na2O ionic or covalent in nature?

Sodium oxide or Na₂O is ionic in nature.

7. What is the formula of sodium oxide?

The molecular formula of sodium oxide is Na₂O.

8. What is sodium dioxide and sodium monoxide?

Sodium monoxide seems like granules which are white in color, reacting with water to give sodium hydroxide which is an exothermic reaction, with evolution of heat. It is used in chemistry in manufacturing units. It is corrosive in nature. Sodium dioxide is an inorganic compound with the chemical formula Na₂O₂. It is a yellow color solid and is strongly basic in nature.

9. Na2O is acidic or basic?

Sodium oxide is basic.

10. What is the difference between sodium oxide (Na2O) and sodium peroxide (Na2O2)?

While both are oxides of sodium, they differ in their oxygen content and properties. Sodium oxide (Na2O) contains O2- ions, while sodium peroxide (Na2O2) contains O22- (peroxide) ions. Na2O2 is more reactive and releases oxygen when decomposed, making it useful as a bleaching agent and oxygen source.

11. What role does sodium oxide play in the production of glass?

Sodium oxide is an important component in glass production, acting as a flux to lower the melting point of silica (SiO2). It helps to reduce the viscosity of the molten glass, making it easier to work with. The presence of Na2O in glass also affects its properties, such as thermal expansion and chemical durability.

12. Why is sodium oxide considered a reducing agent?

Sodium oxide is considered a reducing agent because the oxide ion (O2-) can donate electrons to other species. In reactions, it can reduce other compounds by giving up electrons, while itself being oxidized. This property makes Na2O useful in certain metallurgical processes and chemical syntheses where reduction is required.

13. What happens when sodium oxide is exposed to carbon dioxide?

When sodium oxide is exposed to carbon dioxide, it reacts to form sodium carbonate:

14. Why is sodium oxide stored under anhydrous conditions?

Sodium oxide is stored under anhydrous conditions because it reacts vigorously with water vapor in the air to form sodium hydroxide. This reaction can cause the oxide to absorb moisture, changing its composition and properties. Anhydrous storage prevents this unwanted reaction and maintains the purity of the compound.

15. What is sodium oxide (Na2O) and how is it formed?

Sodium oxide (Na2O) is an ionic compound formed when sodium metal reacts with oxygen. It consists of sodium cations (Na+) and oxide anions (O2-) in a 2:1 ratio. The formation occurs when sodium is exposed to air or oxygen, resulting in a vigorous exothermic reaction.

16. How does the formation of sodium oxide relate to the reactivity series of metals?

The formation of sodium oxide illustrates sodium's high position in the reactivity series of metals. Sodium readily reacts with oxygen due to its low ionization energy and high reactivity, forming a stable oxide. This behavior is characteristic of alkali metals, which are at the top of the reactivity series and easily lose electrons to form ionic compounds.

17. How does the formation of sodium oxide demonstrate the periodic trends in the s-block elements?

The formation of sodium oxide demonstrates several periodic trends in s-block elements:

18. How does the formation of sodium oxide demonstrate the loss of metallic properties?

The formation of sodium oxide demonstrates the loss of metallic properties as sodium transitions from a shiny, malleable metal to a brittle, ionic compound. This change occurs because the sodium atoms lose their outer electrons to oxygen, forming a strong ionic bond instead of the delocalized electrons characteristic of metals.

19. What is the role of sodium oxide in the sodium-oxygen battery concept?

In the sodium-oxygen battery concept, sodium oxide plays a crucial role as a discharge product. During discharge, sodium reacts with oxygen to form Na2O (or sometimes Na2O2), storing electrical energy as chemical energy. The reversibility of this process is key to the battery's function, although challenges remain in practical implementation.

20. Why does sodium oxide have the formula Na2O instead of NaO?

Sodium oxide has the formula Na2O because of the charge balance between sodium and oxygen ions. Sodium forms a +1 ion (Na+), while oxygen forms a -2 ion (O2-). To achieve electrical neutrality, two sodium ions are needed for every oxide ion, resulting in the formula Na2O.

21. What is the significance of the oxide ion in sodium oxide?

The oxide ion (O2-) in sodium oxide is significant because it's a strong base and a powerful reducing agent. It readily accepts protons in aqueous solutions, forming hydroxide ions. The presence of oxide ions contributes to the basic nature of Na2O and its ability to react with acids and water, making it important in various chemical processes.

22. How does the hydration energy of sodium oxide compare to other ionic compounds?

Sodium oxide has a high hydration energy compared to many other ionic compounds due to the small size and high charge density of the oxide ion (O2-). This high hydration energy contributes to its vigorous reaction with water and its tendency to form stable hydrates, making it highly soluble in water.

23. Why is sodium oxide not found naturally in the Earth's crust despite sodium's abundance?

Despite sodium's abundance, sodium oxide is not found naturally in the Earth's crust because of its high reactivity with water and carbon dioxide. In the presence of these common substances, Na2O quickly converts to more stable compounds like sodium hydroxide or sodium carbonate. The Earth's moist, CO2-rich environment prevents the existence of pure sodium oxide in nature.

24. How does the bond energy of Na-O in sodium oxide compare to other metal-oxygen bonds?

The Na-O bond in sodium oxide is relatively strong compared to many other metal-oxygen bonds, but weaker than those in transition metal oxides. Its strength lies between that of ionic and covalent bonds, reflecting the partial ionic character of the Na-O interaction. This bond energy influences the compound's stability and reactivity.

25. Why is sodium oxide considered a basic oxide?

Sodium oxide is considered a basic oxide because it reacts with water to form a strong base (sodium hydroxide). This behavior is characteristic of metal oxides, especially those of alkali and alkaline earth metals, which produce hydroxide ions in aqueous solutions, increasing the pH.

26. How does the melting point of sodium oxide compare to that of sodium metal?

The melting point of sodium oxide (1,132°C) is significantly higher than that of sodium metal (97.8°C). This large difference is due to the strong ionic bonding in Na2O compared to the weaker metallic bonding in sodium metal, requiring more energy to break the ionic lattice.

27. What color is sodium oxide, and why?

Pure sodium oxide is a white, crystalline solid. The white color is due to its ionic nature, where electrons are tightly bound in the ionic lattice. Unlike transition metal oxides, Na2O doesn't have partially filled d-orbitals that could absorb visible light and produce color.

28. What happens when sodium oxide reacts with water?

When sodium oxide reacts with water, it forms sodium hydroxide (NaOH) in a highly exothermic reaction:

29. How does the reactivity of sodium oxide compare to other Group 1 oxides?

Sodium oxide is highly reactive, but its reactivity is intermediate among Group 1 oxides. It is more reactive than lithium oxide (Li2O) but less reactive than potassium oxide (K2O), rubidium oxide (Rb2O), and cesium oxide (Cs2O). This trend follows the increasing reactivity down the group due to larger atomic size and easier electron loss.

30. How does the structure of sodium oxide differ from that of sodium metal?

Sodium metal has a body-centered cubic structure with metallic bonding, while sodium oxide has an antifluorite crystal structure. In Na2O, oxide ions occupy the corners and center of a cubic lattice, with sodium ions filling the tetrahedral holes between them, resulting in a more rigid, ionic structure.

31. How does the density of sodium oxide compare to that of sodium metal?

The density of sodium oxide (2.27 g/cm³) is higher than that of sodium metal (0.97 g/cm³). This increase in density is due to the more compact ionic lattice structure of Na2O compared to the less dense metallic structure of sodium, as well as the addition of oxygen atoms.

32. How does the crystal structure of sodium oxide influence its physical properties?

The antifluorite crystal structure of sodium oxide, where oxide ions occupy the corners and center of a cubic lattice with sodium ions in tetrahedral holes, influences its physical properties. This structure results in a high melting point, brittleness, and electrical insulation in the solid state due to the strong ionic bonds and lack of mobile charge carriers.

33. How does the electronegativity difference between sodium and oxygen affect the properties of sodium oxide?

The large electronegativity difference between sodium (0.93 on the Pauling scale) and oxygen (3.44) results in a highly ionic bond in sodium oxide. This ionic character contributes to its high melting point, brittleness, and solubility in polar solvents. It also explains the compound's reactivity with water and its ability to form strong bases.

34. How does sodium oxide conduct electricity in solid and molten states?

Solid sodium oxide is an electrical insulator due to the fixed positions of ions in its crystal lattice. However, when molten, Na2O becomes a good conductor of electricity as the ions become mobile and can carry charge, allowing for electrolysis and other electrochemical processes.

35. What is the importance of sodium oxide in ceramic glazes?

In ceramic glazes, sodium oxide acts as a flux, lowering the melting point of the glaze mixture. It helps to create a smooth, glossy surface and can influence the color and texture of the glaze. Na2O also affects the thermal expansion coefficient of the glaze, which is crucial for preventing cracking and crazing in finished ceramics.

36. How does the solubility of sodium oxide in water compare to its solubility in organic solvents?

Sodium oxide is highly soluble in water due to its ionic nature and the formation of hydrated ions. However, it is generally insoluble in non-polar organic solvents. This difference in solubility is due to the polar nature of water molecules, which can effectively solvate the Na+ and O2- ions, unlike non-polar organic solvents.

37. What is the significance of sodium oxide in the Castner process?

In the Castner process, an outdated method for producing sodium, sodium oxide played a role in the electrolysis of molten sodium hydroxide. The process involved the formation and decomposition of sodium oxide as an intermediate step. While no longer used commercially, understanding this process helps in comprehending the chemical behavior of sodium compounds.

38. How does the presence of sodium oxide affect the pH of an aqueous solution?

The presence of sodium oxide significantly increases the pH of an aqueous solution. When Na2O dissolves in water, it forms sodium hydroxide (NaOH), a strong base:

39. Why is sodium oxide considered an example of a nonstoichiometric compound?

Sodium oxide can exhibit nonstoichiometric behavior, meaning its composition can deviate slightly from the ideal Na2O formula. This occurs due to defects in the crystal structure, such as oxygen vacancies or interstitial sodium ions. These defects can affect the compound's properties and reactivity, demonstrating the complexity of real-world chemical systems.

40. How does the heat of formation of sodium oxide compare to other alkali metal oxides?

The heat of formation of sodium oxide is more exothermic than that of lithium oxide but less exothermic than those of heavier alkali metal oxides (K2O, Rb2O, Cs2O). This trend reflects the balance between the energy required to ionize the metal and the lattice energy of the resulting oxide, which varies with ionic size and charge density.

41. What role does sodium oxide play in the corrosion of sodium metal?

Sodium oxide plays a crucial role in the corrosion of sodium metal. When sodium is exposed to air, a thin layer of Na2O forms on the surface. Unlike some metal oxides that form protective layers, sodium oxide is hygroscopic and reacts with moisture to form sodium hydroxide. This process continues, leading to the progressive corrosion of the sodium metal.

42. How does the presence of sodium oxide affect the optical properties of glass?

The presence of sodium oxide in glass affects its optical properties by lowering the refractive index compared to pure silica glass. It also increases the dispersion of light, which can lead to chromatic aberration in optical systems. Additionally, Na2O can introduce absorption bands in the infrared region, affecting the glass's transmission spectrum.

43. What is the relationship between sodium oxide and the flame test for sodium?

While the flame test for sodium produces a characteristic yellow color, this is not directly due to sodium oxide. The yellow color comes from excited sodium atoms in the gas phase. However, when sodium compounds (including Na2O) are introduced into a flame, they decompose and produce these excited sodium atoms, indirectly linking sodium oxide to the flame test result.

44. How does the thermal conductivity of sodium oxide compare to that of sodium metal?

The thermal conductivity of sodium oxide is significantly lower than that of sodium metal. This difference is due to the contrasting bonding types: Na2O has an ionic lattice where heat is conducted primarily through lattice vibrations (phonons), while sodium metal has free electrons that efficiently conduct heat. This property difference affects their respective uses in thermal applications.

45. What is the significance of sodium oxide in the production of sodium hydroxide?

While sodium hydroxide is primarily produced by the chloralkali process, sodium oxide can be used as an alternative starting material. The reaction of Na2O with water produces NaOH directly:

46. How does the presence of impurities affect the properties of sodium oxide?

Impurities can significantly affect the properties of sodium oxide. Common impurities like sodium peroxide or sodium carbonate can alter its reactivity, melting point, and chemical behavior. For example, peroxide impurities can make the compound more reactive with water and organic materials, while carbonate impurities might affect its basicity and solubility.

47. What is the role of sodium oxide in certain types of concrete?

In certain types of concrete, particularly those using alkali-activated binders, sodium oxide plays a role in the activation process. It contributes to the alkalinity necessary for the dissolution of aluminosilicate precursors and the formation of binding phases. The presence of Na2O can affect setting time, strength development, and durability of the concrete.

48. How does the electron configuration of sodium and oxygen atoms influence the formation of sodium oxide?

The electron configuration of sodium (1s² 2s² 2p⁶ 3s¹) and oxygen (1s² 2s² 2p⁴) directly influences the formation of sodium oxide. Sodium easily loses its single 3s electron to achieve a stable noble gas configuration, while oxygen gains two electrons to fill its 2p orbital. This electron transfer results in the formation of Na+ and O2- ions, which then combine to form Na2O.

49. What is the importance of sodium oxide in understanding the concept of basic anhydrides?

Sodium oxide is an excellent example of a basic anhydride, a concept crucial in acid-base chemistry. As a basic anhydride, Na2O forms a base (NaOH) when reacted with water. This behavior contrasts with acidic anhydrides (like CO2) that form acids with water. Understanding Na2O as a basic anhydride helps in grasping the relationship between oxides and their corresponding acids or bases.

50. How does the lattice energy of sodium oxide compare to other ionic compounds?

The lattice energy of sodium oxide is relatively high compared to many other ionic compounds due to the high charge-to-size ratio of the O2- ion and the strong electrostatic attraction between Na+ and O2- ions. This high lattice energy contributes to its stability, high melting point, and the energy released during its formation from elements.

51. What role does sodium oxide play in the sodium-sulfur battery technology?

In sodium-sulfur battery technology, sodium oxide can form as an unwanted side product if oxygen contamination occurs. Its presence can affect the battery's performance and longevity. Understanding the potential formation and effects of Na2O is crucial for designing and maintaining these high-temperature battery systems.

52. How does the formation of sodium oxide demonstrate the concept of oxidation numbers?

The formation of sodium oxide clearly demonstrates the concept of oxidation numbers. In this reaction, sodium