OCS Lewis Structure: Drawings, Hybridization, Shape, Charges,Pair And Detailed Facts


Ocs is a colourless gas molecule and can cause toxicity at high concentration.

In the ocs leweis structure with the help of the outer orbit electrons, the most stabilized configuration of the molecule can be determined. In an electron dot structure all electrons are not considered as they strongly bounded through nuclear force.

How to draw lewis structure for OCS

Lewis structure is a diagram where the basic bonding skeleton of a molecule is shown.

The ocs lewis structure shows the atoms involve in the molecule with their position by using the atomic symbols. Around the atomic symbols excess electrons (beside bonding electrons) are represents by dot signs in the Carbonyl Sulfide molecule.

In modern Periodic table Oxygen and Sulfur are in group16 and Carbon is in group 14. The last shell electronic arrangement of Oxygen atom is [He] 2s2 2p4. That arrangement of Sulfur atom: [Ne] 3s2 3p4. This order of electrons in Carbon atom is [He] 2s2 2p2.

Hence to form the ocs lewis structure, total sixteen negatively charged particles (4 + 6 + 6) are available in the outer most energy levels of the participated atoms. So there are eight pairs of electron for bond formation.

To draw the ocs lewis structure we have to identify the less electronegative molecule which becomes the central atom. Because it has less affection to pull the electron cloud of the bonding and it can share maximum electrons for full fill the orbital of next atom. Among these, Carbon is less electro-negative, so is placed in the center of the molecule.

After arrangement of the atoms; electrons are placed according to their parent atom. Now to achieve full octet (eight electrons in last orbit), atoms shares electrons and form bonds.  Two electron cloud coordinate to make a single bond which is shown by a straight line in electron dot structure.

Among the valence electrons of carbon, two make double bond (π- bond) with Oxygen atom and other two make pi bond (π) with Sulfur atom and completes its outer shell with eight electrons. In this structure both Oxygen and Sulfur atoms has four excess unshared electrons.

OCS lewis structure shape

Electron cloud repels each other until there is minimum repulsion between adjacent bonds in a electron dot structure to stabilize the structure of a molecule. This is the core statement of VSEPR theory.

There is no unshared electron over the central Carbon atom. So its original geometry remains undisturbed and for this the shape of ocs lewis structure is also linear as well as its geometry.

ocs lewis structure
ocs lewis structure shape

OCS lewis structure formal charges

Formal charge is used to calculate the individual charge of atoms of a molecule to compare the energetic stability of the electron dot structure.

Formal charge of an atom in ocs lewis structure can be calculated by the equation, (total number of last orbit electrons –unshared electrons of the atom – (1/2× electrons in bonding pairs)).

From the Periodic table, we know that each of Oxygen and Sulfur atoms contain six electrons and Carbon atom has four electrons in the last occupied electronic shell. Sulfur and Oxygen each have four excess electrons which remain as non bonding electrons (lone pairs).

Carbon atom formal charge in the electron dot structure, {4- 0- (1/2×8)} = 0.

For both Oxygen and Sulfur atoms calculated formal charge is, {6- 4- (1/2×4)} = 0.

As the atoms of this particular electron dot structure of the molecule have “zero” (0) formal charge, hence the electronic arrangement of this ocs lewis structure is very much stable as compared.

OCS lewis structure lone pairs

In chemistry a pair of electrons which is not shared to produce a chemical bond with neighbor atom is called lone pair.

To form ocs lewis structure, sixteen outer shell electrons of the three atoms involve. Among these, four pairs (eight electrons) of electron result in chemical bond formation. Four pairs of electrons remain as excess, which are called lone pair electrons of Carbonyl Sulfide molecule.

Lone electron pair is a negative charged cloud which has high charge density compared to the bonding electron pair. This is because it remains in the control of only one atom and near to its nucleus. Whereas bonding electron cloud remain in the average distance of the two atomic radiuses.

For the high charge density it is bulky and as a result its repulsive nature is greater. So it affects the shape of a molecule if its central atom has the unshared electron pair.

OCS hybridization

Valence bond theory explains atomic orbitals with comparable energies are intermixes to produce new hybrid orbital with different shape and energy.

In the lowest energy level, Carbon atom has two unpaired 2p orbital electrons and one vacant 2p orbital. It also contains one paired electron in the 2s orbital, so one electron from this can transferred to the vacant 2p orbital.

After the transition of the electron, the 2s orbital mixes with one 2p orbital and produced sp hybridized orbital. Remaining two pure 2p orbitals can form two double bonds (π- bond) with Oxygen and Sulfur respectively.

OCS lewis structure resonance

If the unshared electrons of an atom move to adjacent atom then we get a different electron dot structure, which is called resonance structure of the electron dot structure.

In the ocs lewis structure both Oxygen and Sulfur have extra electrons except bonding pairs. These electron clouds can move to the next atom and create charge separation which can be calculated from formal charge equation.

From the neutral electron dot structure, one bonding electron pair between Sulfur and Carbon can delocalize to the Oxygen orbital. This causes extra electron density to the Oxygen atom and electron cloud density vacancy to the Sulfur atom and vice versa. Thus we get the resonance structures of the Carbonyl Sulfide molecule.

OCS lewis structure octet rule

This rule states that the involving atoms of the ocs lewis structure organize themselves in a way that each of them contain eight electrons in their outer energy level shell. This arrangement of the electrons becomes similar like inert gases.

Oxygen and Sulfur both of these elements have six electrons in their outer s and p orbital, where Carbon atom has four electrons in the s and p orbital of 2nd shell.

They share the electron cloud in such a way that they make up the deficiency of electrons in the outer shell. This type of electron orientation decreases the energy level of the molecule, which help the ocs lewis structure to be stable.

OCS polar or nonpolar

Dipole arises in a molecule if there is separation of charge between atoms. Dipole moment (µ) of a bond can be known by product of the separated charge (δ) and distance between charges (r).

In the Carbonyl Sulfide molecule, electro-negativity of Oxygen (O) is 3.44, sulfur is 2.58 and that of Carbon is 2.55 on the Pauling scale. This difference in the capacity of the bond electron cloud pulling results a net dipole moment and Carbonyl Sulfide becomes polar molecule.

If the electro-negativity difference of involving atoms is 0.4 or more than this, a dipole is generating in the bond. That means the bonding electron cloud shifted towards one end of the bond which becomes slightly negative than the other end. It produces a direction vector component towards the negative end.

From the shape of the molecule we see that Oxygen and Sulfur are in opposite direction from Carbon atom. For being more electronegative atom, the C-O bonding electron cloud is more shifted to the Oxygen side than the Sulfur side of the C-S bond. So the vector direction of the net dipole moment is towards Oxygen atom.

ocs lewis structure
ocs lewis structure polarity vector

The atoms of the Carbonyl Sulfide molecule are joined in linear position. This is in such a way that the electron cloud repulsions of both bonding and unshared are not disturbed the geometry of molecule. Hence the dipole vectors can’t balance equally and ocs lewis structure becomes polar.

OCS lewis structure bond angle

In a 3D space orientation (geometry) of molecular lewis structure the angle between three adjacent atoms is called bond angle.

The central atom Carbon is sp hybridized in the electron dot structure, where the three atoms are connected linearly. So the possible bond angle in the ocs molecule is 180̊.

The arrangement of number of the bonding and unshared electron cloud is in a symmetric way from the central atom. Both Oxygen and Sulfur have four non-bonding electron cloud. So the bond of both sides from Carbon atom faces similar repulsive forces which makes molecule linear with 180̊ bond angle.

OCS lewis structure electron geometry

Theoretically Valence shell electron pair repulsion theory can predict the geometry of ocs lewis structure.

Different spectroscopic methods help to detect a molecular geometry. In the basis of the information of the hybridization of central atom, bond length, angle between bonds, general shape of the molecule we can conclude what a geometry of this molecule should be.

In the ocs lewis structure double bond is present in the both side of the central Carbon atom which is sp hybridized. That means three atoms are present on same plane of paper in a liner fashion. Central atom has no unshared electron, so the linear geometry of ocs lewis structure can not be distorted by repulsion of electron cloud.

OCS valence electrons

Negative charged particles (electron) are circulated around the nucleus of an atom. Among these particles which are in the last energetic shell are called valence electrons.

OCS lewis structure has sixteen outer orbit electrons. Both Oxygen and Sulfur atoms have six outer shell electrons and the Carbon atom has that of four.

In an atomic structure model the negative charged particles are moving around the nucleus which is at the center. With increasing the distance between the nucleus and the electronic energy level, the force which binds these together tends to decrease.

For this reason the valence electrons (outer orbit electrons) are loosely bound by nucleus force of attraction and easily can participate in reactions.

OCS uses

OCS is one of the abundant compounds of element Sulfur which plays a symbolic roll in the source of life. It is produced as intermediate in various reactions.

In plants Carbonyl Sulfide is transferred to Hydrogen Sulfide by enzyme catalysis reaction. Because of this reaction, studies of OCS are used to observe rate of photosynthesis.

It is an important compound in the cycle of Sulfur in our environment. By measuring the levels of Carbonyl Sulfide over a period of time from the Antarctica, we clearly see the impact of human activities in our ecosystem.

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