Covalent Bond

Covalent bonds are very important in chemical bonds because almost all organic compounds are made up of covalent bonds. Water is one of the main constituents of our life compound formed by a covalent bond. Compounds formed by covalent bonds are called covalent compounds. Therefore, water is a covalent compound.

In the previous article, we discussed ionic bonding. Which one is stronger in chemical bonds? Ionic bond or covalent bond? Of course, ionic bonds are stronger. They are stronger because two differently charged ions are attached to each other by attraction. So what happens to the covalent bond?

[ Covalent Bond | Chemical Gurukul ]

Elements share electrons in covalent bonds, but how do electrons are shared in covalent bonds? An element forms a bond pair electron by sharing a bond electron of its last energy level with a bond electron of the last energy level of another atom. And this shared electron pair is called a bond pair electron. A bond pair electron has two electrons. Interestingly, the two electrons come from two different elements.

The Ionic Bonding article explains the Rule of Octate and the stability of the elements. The issue of stability will be equally applicable here. The electrons of the last energy level, which are in pairs but do not participate in bond formation, are called lone pair electrons. The sum of these lone pair electrons and bond pair electrons is eight in total and thus they can take the form of the last energy level as s2p6 or near inert element (Noble gas).

Covalent Bond

The figure above shows the electrons of the last energy level of carbon (C) and oxygen (O). The electrons of C are denoted by green and the electrons of O are denoted by red. In the last energy layer of carbon, two pairs of bond electrons are seen on both sides.

CO2 is a covalent compound. Through electron sharing, carbon and oxygen combine to form carbon dioxide, and the internal atoms are stabilized.

The repulsion of loan pair electrons is greater than bond pair electrons. The electron configuration of the elements is detailed in the article “Electron configuration” on ChemistryGOLN.com. And the VSEPR theory was only mentioned in the “Chemical Bonding” article. The next article will deal with the geometric shapes of bonding angles and covalent compounds.

Now, if we think more deeply about electron share in covalent bonds, we can see that each element is actually unstable with its electron configuration and they want to be stable. The model element for their stabilization is the inert gases located in group no. 18 of the periodic table.

There are many types of bonding of covalent compounds. For example, H-Cl is a bond, and H-H is a bond. Bond Energy will be different for each bond.

Again, the sigma bond and the “pie” bond are very familiar names in the covalent bond of organic compounds.

 

 

Sigma and pie bonding are shown in three pictures side by side. The first picture shows the hybridization of the energy level, the next picture shows the C-C sigma bond and the next picture shows a sigma of C = C double bond and a “pi” bond.

In organic compounds, single bonds are sigma bonds and double bonds or triple bonds. The first bond is the sigma bond and the other bonds are “pie” bonds.

 

As shown in the figure above, the single bonds are sigma bonds and Propene has a double bond, where one is a sigma bond and the other is a “pi” bond.

 

Sigma bonds are much stronger than pie bonds and sigma bonds cannot be easily broken apart. We will discuss this in detail in ChemistryGOLN.com’s “Organic Compounds” article.

In the case of inorganic covalent compounds, it is very important to identify the loan pair and bond pair electrons. We will now look at it through a diagram and a table.

 

 

Ne is an inert element, it appears to have no bonded electrons. However, during the formation of methane (CH4 ) all the electrons of the last energy level participate in the stock and there are no lone pair electrons. All the electrons here have turned into bond pairs. In the middle figure, two Fluorines combine to form F-F or F2 covalent compounds.

Now we will explain how water (H2O) is a covalent compound.
Electron Configuration of Hydrogen is, 1H => 1s1
And, Electron Configuration of Oxygen is, 😯 => 1s2 2s2 2px2 2py1 2pz1

As it turns out, H has only one energy level, where there is one electron. It wants to be like helium according to the Duet Rule. So H felt the need for one more electron in his 1s. Oxygen has one electron in 2py and 2pz, they need one more electron in total to be like Ne. The two hydrogens then form one H2O covalent compound by sharing electrons one by one with oxygen.

The figure shows the covalent structure of a water molecule.
Similarly, the structure of CCl4 is shown below.

 

The number of covalent compounds on Earth is comparatively much higher than that of ionic compounds.

 

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