O2 is the most essential element for human beings for respiration, it is colorless gas having a molecular weight of 32 g/mol. Let us discuss more O2 in this article.
O2 is consist of two O atoms and the environment around both O atoms is the same. Both O atoms are sp3 hybridization. To satisfy the valency and complete the octet both O formed a double bond between them via sharing electrons. The shape of the molecule is linear and the bond distance between two O is 116 pm.
The bond distance is less than expected due to the double bond character between two O atoms. That’s why the bond is more rigid. We can explore more about O2 bonding mode, lewis structure, hybridization, polarity, and other important facts in detail in the following sections.
1. How to draw the O2 lewis structure?
The drawing of lewis structure of O2 helps us to find out the previous important part. Let’s try to draw the O2 lewis structure in a few steps with an explanation.
Counting the valence electrons
Valence electrons are the most important things to draw lewis structure. First of all, we calculate the total valence electrons for the O2 molecule and the value is 12. Which is the contribution from both O atom valence electrons individually and each O contributes 6 as valence electrons, added together.
Choosing the central atom
The central atom is an important part of the molecule because based on the central atom different physical and chemical property is decided for a molecule. Here we can differentiate the central atom because both are the same, and both have the same property. So, we choose one O as the central atom.
Satisfying the octet
It should be verified while drawing the lewis structure that every atom follows the octet rule by completing its valence orbital to accept or share the required number of electrons. Here both O atoms should be completed their valence shell by sharing electrons in between them via two covalent bonds.
Satisfying the valency
After successive bond formation, we check if the valency of every atom should be justified. O2 needs 8*2 = 16 electrons when following the octet but it has 12 valence electrons. So, the remaining 16-12 = 4 electrons should be shared by 4/2 = 2 bonds. O is divalent, so each O makes a double bond to satisfy.
Assign the lone pairs
Extra remaining non-bonded electrons present over the valence orbital of a particular atom should be placed as lone pairs over that atom. Each O has six valence electrons. While bond formation only two electrons are involved so the remaining four electrons exist as two pairs of lone pairs over each O atom.
2. O2 valence electrons
Valence electrons are present over the outermost shell of each atom and they are involved in bond formation. Let us calculate the valence electrons for O2 in next part.
The total valence electrons for the O2 molecule are 12. This is the value of the summation of valence electrons of two O atoms together. Each O has six valence electrons as per its electronic configuration. So, for a molecule, the number of valence electrons comes from the valence electrons of the atom.
- Let us calculate the valence electrons of the O2 molecule.
- The electronic configuration of O is [He]2s22p4
- The valence electrons of each O atom are 6.
- So, in the O2 the total valence electrons are 6*2 = 12
3. O2 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 O2.
Each O carries lone pairs in the O2 molecule. There are two pairs of lone pairs carried by each o atom. O has four non-bonded electrons present in its valence shell after the formation of the double bond because it is a group VIA element. O is divalent so the remaining four electrons exist as lone pairs.
- Lone pairs are calculated by the following formula, non-bonded electrons = valence electrons – bonding electrons.
- The lone pairs over each O atom are, 6-2 = 4 (two pairs)
- The lone pairs over O2 molecule are 4*2 = 8 (four pairs)
4. O2 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 O2 in detail.
Both O atoms completed their octet in O2 via sharing electrons within the bonds. The stable valence of O is 2 and it is confirmed from its electronic configuration, [He]2s22p4. So, O try to make a double bond for stability, and here both O formed a double bond with each other by sharing four electrons.
O belongs to the p block element which is also confirmed by its electronic configuration. So, according to the octet rule which is applied for the p block element which is p block element complete its valence shell by a total of eight electrons. Making double bonds each O atom gets eight electrons in octets.
5. O2 lewis structure shape
Lewis structure shape is very particular for that molecule that has the same environment. Now we try to learn about the shape of O2 in the following section.
The shape of the O2 molecule is linear which is confirmed by the following table.
| Molecular Formula | No. of bond pairs | No. of lone pairs | Shape | Geometry |
| AX | 1 | 0 | Linear | Linear |
| AX2 | 2 | 0 | Linear | Linear |
| AXE | 1 | 1 | Linear | Linear |
| AX3 | 3 | 0 | Trigonal planar | Trigonal Planar |
| AX2E | 2 | 1 | Bent | Trigonal Planar |
| AXE2 | 1 | 2 | Linear | Trigonal Planar |
| AX4 | 4 | 0 | Tetrahedral | Tetrahedral |
| AX3E | 3 | 1 | Trigonal pyramidal | Tetrahedral |
| AX2E2 | 2 | 2 | Bent | Tetrahedral |
| AXE3 | 1 | 3 | Linear | Tetrahedral |
The environment around both O atoms is trigonal planar. It is an AXE2 type of molecule from the above table, having one bond pair and two lone pairs. According to the VSEPR (Valence Shell Electron Pair Repulsion) theory, it has a linear shape, and the double bond between two O atoms stays in the linearity.
6. O2 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 O2 in the next part.
The bond angle between two O atoms is 1800 because it is a linear molecule, and the linear molecule has sp hybridized. From the hybridization value, it is also confirmed that the particular value. Again, there is no lone pairs repulsion between two O atoms, so the bond angle is perfectly 1800.
- Actually, the bond angle is predicted by the bents rule of hybridization, COSθ = s/(s-1).
- The hybridization of O2 is sp, so s character is 1/2th.
- So, the bond angle is, COSθ = {(1/2)} / {1-(1/2)} = -1
- Θ = COS-1(-1) = 1800
- Which is the perfect bond angle for linear molecules like O2.
7. O2 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 O2.
The formal charge of O2 is zero because it is a neutral molecule. O is a stable divalent molecule and for this reason, it can be formed a double bond. So, there is no charge is present within the molecule because the valency of two O atoms is fully satisfied by a double bond so no need to present a charge.
- Let us check the value of the formal charge present over H or P by the formula, F.C. = Nv – Nl.p. -1/2 Nb.p.
- The formal charge present over each O atom is, 6-4-(4/2) =0
- So, the formal charge present over the O2 molecule is zero.
8. O2 lewis structure resonance
Resonance is the delocalization of electron clouds through different skeleton forms of the molecule. Let’s see whether is possible for the O2 resonating structure or not.
There is no resonating structure observed in the O2 molecule because both O atoms are electronegative so they do not try to release electron density from its sigma orbital. Although there is a π bond present so π electron density is also present but it cannot be delocalized.
O atom is a more electronegative atom and it attracts the electron density towards itself. So, in the O2 molecule, no chance of delocalized electron density between two O atoms, and no skeleton forms are observed. No resonance is possible in the O2molecule.
9. O2 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 O2.
The Hybridization of O2 is predicted from the following table which is sp2
| Structure | Hybridization value | State of hybridization of central atom | Bond angle |
| Linear | 2 | sp /sd / pd | 1800 |
| Planner trigonal | 3 | sp2 | 1200 |
| Tetrahedral | 4 | sd3/ sp3 | 109.50 |
| Trigonal bipyramidal | 5 | sp3d/dsp3 | 900 (axial), 1200(equatorial) |
| Octahedral | 6 | sp3d2/ d2sp3 | 900 |
| Pentagonal bipyramidal | 7 | sp3d3/d3sp3 | 900,720 |
- 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+0+0+0) = 3 (sp2)
- One s orbital and two p orbitals of O are involved in the hybridization.
- The lone pairs are also included in the hybridization.
10. Is O2 solid or gas?
The physical nature of a molecule is dependent on the atomic interactions among atoms and entropy at room temperature. Now see whether O2 is solid or gas.
O2 is gaseous at room temperature because the atomic interactions between two O atoms are not so high, so the diffuseness between two O atoms is high and for this reason, the entropy is also high. Also, the density of the O2 molecule is very low and van der Waal’s interaction is very low for O2 molecules.
Why and how O2 is gaseous?
O2 is gaseous because van der Waal’s interaction between two O atoms is very weak, so both O atoms lie apart from each other. For this reason, the lattice form of an oxygen molecule is loosely bound and exists as a gas at room temperature. It can be solidified at a very lower temperature.
11. Is O2 soluble in water?
The solubility in water for a molecule should be gets dissolved in water and then it should be soluble. Let’s see whether O2 is soluble in water or not.
O2 is insoluble in water like another gaseous molecule. For a gaseous molecule, it is very difficult to soluble in an aqueous solution. They are adsorbed in solution rather than soluble. It needs more pressure or high temperature but after application of such experimental condition, few parts are soluble.
Why and how O2 is insoluble in water?
O2 is insoluble in water because it is a non-polar molecule. We know like dissolved like and water is a polar solvent and. So, for non-polar molecules soluble in a polar solvent is very difficult. Also, it is a gaseous molecule and cannot get dissolved in water. Although the lone pairs of O2 can form H bond.
12. Is O2 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 O2.
O2 is non polar and the main reason is the shape of the oxygen is symmetric concerning both atoms. So, the direction of the dipole-moment will be opposite and the magnitude of the dipole-moment value is equal. So, there is canceling the dipole-moment value by each other and making the molecule non-polar.
Why and how O2 is non-polar?
O2 is non-polar because the resultant dipole-moment value is zero here. The electronegativity difference between two O atoms is always zero because both are the same substituent and their electronegativity value is the same. Again, the dipole-moment direction is opposite so they cancel out each other.
13. Is O2 neutral?
A molecule is said to be neutral when its octet is fully satisfied or multiple bonds are present within the molecule. Let’s see whether O2 is neutral or not.
O2 is a neutral gaseous molecule. There is a double bond present within the molecule so when it is involved in a reaction the double bond needs to be broken, which required more energy than a single bond. Also, the lone pairs are present in the electronegative orbital and attached by strong electronic force.
Why and how O2 is neutral?
O2 is neutral because there needs more energy to break its double bond to participate in the chemical reaction. Also, O is more electronegative so it cannot be released in lone pairs easily and makes neutral in many reactions. But the elemental O is a more reactive species and participates in many reactions.
14. Is O2 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 O2 is a molecular compound or not.
O2 is not a molecular compound although the di valency of both O atoms is satisfied here but it is not a solid or has properties like them. O2 is formed by two oxygen atoms in the same ratio if the ratio is changed then oxygen is not existing it changed to ozone (O3).
Why and how O2 is not a molecular compound?
O2 is not a molecular compound because it is not a solid molecule having interactions between two atoms. It is a gaseous molecule and for being a compound it should be a mixing of two different atoms but here both atoms are the same, although it maintained the fixed ratio and proper valency.
15. Is O2 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 O2 is covalent or ionic.
O2 is a covalent molecule and both O atoms are sharing electrons in the bond present between two O atoms. There is no ionic interaction present between two O atoms and also there is no chance of polarizing and polarizability because both are the same element.
Why and how O2 is covalent?
O2 is a covalent molecule because the bond present between two O atoms is formed by the sharing of electrons between two O atoms. The bond is non-polar, so there is no chance of ionic interaction. Here cation and anion both are the same they are vice versa so no application of Fajan’s rule.
Conclusion
O2 is a very essential gaseous molecule present in the atmosphere. It is diamagnetic in nature, it can bind with iron in the hemoglobin of blood and circulate in the whole body. Without oxygen, no human being will be survived. It helps with combustion.
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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.