How to draw a CBr4 Lewis Structure? - Science Education and Tutorials

Drawing CBr4 Lewis Structure is very easy. Here in this post, we described step by step method to construct CBr4 Lewis Structure.

Table of Contents

Key Points To Consider When drawing The CBr4 Lewis Structure

A three-step approach for drawing the CBr4 Lewis Structure can be used. The first step is to sketch the Lewis structure of the CBr4 molecule, to add valence electron around the carbon atom; the second step is to valence electron to the bromine atom, and the final step is to combine the step1 and step2 to get the CCl4 Lewis Structure.

The CBr4 Lewis structure is a diagram that illustrates the number of valence electrons and bond electron pairs in the CBr4 molecule. The geometry of the CBr4 molecule can then be predicted using the Valence Shell Electron Pair Repulsion Theory (VSEPR Theory), which states that molecules will choose a CBr4 geometrical shape in which the electrons have from one another.

Finally, you must add their bond polarities to compute the strength of the C-Br bond (dipole moment properties of the CBr4 molecule). The carbon-bromine bonds in Carbon tetrafluoride(CBr4), for example, are polarised toward the more electronegative carbon, and because both bonds have the same size, their sum is zero due to the CBr4 molecule’s bond dipole moment, and the CBr4 molecule is classified as a nonpolar molecule.

The molecule of Carbon tetrafluoride (with tetrahedral geometry) is tilted at 109 degrees and has a difference in electronegativity values between bromine and carbon atoms, with bromine’s pull being roughly equal to carbon’s. As a result, it has no dipole moment indefinitely. The CBr4 molecule has no dipole moment due to an equal charge distribution of negative and positive charges.

How to draw the CBr4 Lewis Structure:

The centre atom is carbon, which is bordered on all sides by four bromine atoms. Carbon has four outermost valence electrons, indicating that it possesses four electrons in its outermost shell, whereas bromine only has seven. To complete the octet of the carbon atom, a carbon core atom requires four electrons. If you’re interested in learning more about the carbon octet rule, please see our previous post.

Four bromine atoms establish covalent connections with the carbon atom as a result, leaving the carbon atom without any lone pairs. There are no lone pairs on the carbon core atom that resist the bond pairs of the four C-Br. According to VSEPR theory, no electronic repulsion leads the CBr4 molecule to take on a tetrahedral shape like CH3Cl, CH3F, or CH2Cl2.

The CBr4 molecule’s C-Br bonds are arranged in a symmetrical order around the tetrahedral geometry, giving rise to the tetrahedral shape. The CBr4 molecule has a tetrahedral geometry because there is no electrical repulsion between them.

Electronegative difference calculation CBr4 molecule:

Carbon has an electronegativity of 2.55, while bromine has an electronegativity of 2.22 in the CBr4 molecule. The difference in electronegativity can be estimated using the method below.

The electronegative value difference between carbon and bromine
Electronegativity value of bromine= 2.22
Electronegativity value of carbon= 2.55
Difference of electronegativity value between bromine and carbon= 2.55 – 2.22 =0.33
Electronegativity difference between C-Br bond calculation of CBr4 molecule

Due to the difference in electronegativity value of less than 0.5, the C-Br bond of the CBr4 molecule becomes nonpolar. Because of this difference in electronegativity, the CBr4 molecule’s C-Br bond becomes nonpolar. The electronegativity of an atom is the strength with which it may attract bound electron pairs to its side.

As a result, the C-Br bond’s dipole moment is virtually negligible, and all C-Br bonds’ dipoles are centered around the tetrahedral geometry. The CBr4 molecule’s total dipole moment is predicted to be 0 D. It has a partial negative charge for carbon atoms and a partial positive charge for bromine atoms.

The electron dot structure of the CBr4 molecule is also known as the CBr4 Lewis Structure. It determines the number of outermost valence electrons as well as the electrons engaged in the CBr4 molecule’s bond formation. The outermost valence electrons of the CBr4 molecule must be understood while considering the Lewis structure of the molecule.

The carbon atom is the middle element in molecular geometry, with four electrons in its outermost valence electron shell, whereas the bromine atom has seven electrons in its outermost valence electron shell.

The CBr4 molecule has a total of 32 valence electrons as a result of the foregoing reasoning. With the core carbon atom, the four bromine atoms form covalent bonds, leaving the carbon atom with no lone pairs on it.

The tetrahedral geometry and structure of the molecules are similar to that of the chloroform (CH3Cl) molecule because no lone pairs of central carbon atoms create interaction with C-Br bond pairs. The bond angle of the Br-C-Br bond is approximately 109 degrees. The C-Br bond has a 108-minute bond length (picometer).

To sketch the CBr4 Lewis structure by following these instructions:

Step-1: Adding valence electron on the carbon atom

Calculate the total number of electrons in the CBr4 molecule’s outermost valence shell. The first step is to determine how many electrons are in the CBr4 Lewis Structure’s outermost valence shell. An electron in an atom’s outermost shell is known as a valence electron. It is represented by dots in the CBr4 Lewis Structure diagram. The CBr4 molecule’s core carbon atom can be represented as follows:

To calculate the valence electron of each atom in CBr4, look for its periodic group. The carbon and bromine families, which are the first and 14th groups in the periodic table, are both made up of carbon and bromine atoms. In their outermost shells, carbon and bromine have four and seven valence electrons, respectively.

Because carbon and bromine are members of the periodic table’s carbon and halogen family groups, their valence electrons are four and seven, respectively.

Total outermost valence shell electron of carbon atom in CBr4= 4
Total outermost valence shell electron of bromine atom in CBr4= 1
The CBr4 molecule has one central carbon atom and four bromine atoms. Then the total outermost valence shell electrons can be calculated as follows
∴ Total outermost valence shell electrons available for CBr4 Lewis Structure( dot structure) = 4 +4*7= 32 valence electrons in CBr4
calculation of total valence electron of CBr4 molecule

Choose the atom with the least electronegative charge and insert it in the molecular geometry of CBr4. We’ll choose the least electronegative atom in the CBr4 molecule to place in the centre of the CBr4 Lewis structure diagram in this phase. The electronegativity value in periodic groups grows from left to right in the periodic table and drops from top to bottom.

Step-2: Adding valence electron on bromine atom in the CBr4 molecule

As a result, bromine is the third atom in the periodic table’s halogen family group. Carbon is the first member of the carbon family. The electronegative value of a bromine atom is lower than that of a carbon atom. Furthermore, bromine has a one-electron limit since carbon is the most electronegative element in the CBr4 molecule.

In a CBr4 Lewis Structure diagram, the carbon atom can be the centre atom. As a result, central carbon in the CBr4 Lewis Structure, with all four bromines arranged around the tetrahedral geometry.

Step-3: Combining step1 and step2 to get step3 for CBr4 dot structure

Connect the exterior and core atoms of the CBr4 molecule with four single bonds (C-Br). In this stage, use four single bonds to connect all four bromine atoms on the outside of the CBr4 molecule to the central carbon atom in the middle.

Count how many electrons from the outermost valence shell have been used in the CBr4 structure so far. Each C-Br bond carries two electrons because each carbon atom is connected to four bromine atoms by four C-Br bonds. Bond pairings are what they’re called.

So, out of the total of 32 valence electrons available for the CBr4 Lewis Structure, we used 8 for the CBr4 molecule’s four single (C-Br) bonds. The CBr4 molecule has lost all of its valence electrons. We don’t need to put the extra electron in the molecular geometry of CBr4.

Place the valence electrons in the C-Br bond pairs starting with the core carbon and three bromine atoms in the CBr4 molecule. In the CBr4 Lewis Structure diagram, we always begin by introducing valence electrons from the central carbon atom. As a result, wrap around the central carbon atom’s bond pair valence electrons first.

Carbon requires 8 electrons in its outermost valence shell to complete its octet. Carbon already shares eight electrons thanks to the four single bonds.

We’ve positioned eight electrons around the central carbon atom, which is represented by a dot, in the CBr4 molecular structure above. The carbon atom completes its octet stability in the CBr4 molecule because it possesses 8 electrons in its outermost valence shell.

Count how many outermost valence shell electrons have been used so far using the CBr4 Lewis Structure. Eight electrons are shown as dots in the CBr4 chemical structure, whereas four single bonds each contain two electrons. The outermost valence shell electrons of the CBr4 molecule are 4 + 4= 8 as a result of the calculation.

So far, we’ve used eight of the CBr4 Lewis structure’s total eight outermost valence shell electrons.

Complete the middle carbon atom octet and, if necessary, apply a covalent bond. The core atom in the CBr4 Lewis Structure is carbon, which is bonded to the bromine atoms by four single bonds (C-Br). With the help of four single bonds, it already shares eight electrons. As a result, carbon follows the octet rule and has eight electrons surrounding it.

How to calculate the formal charge on the carbon atom in CBr4 Lewis Structure?

The formal charge on the CBr4 molecule’s carbon central atom often corresponds to the actual charge on that carbon central atom. In the following computation, the formal charge will be calculated on the central carbon atom of the CBr4 Lewis dot structure.

To calculate the formal charge on the central carbon atom of CBr4 molecule by using the following formula:
The formal charge on the carbon atom of CBr4 molecule= (V. E(C)– L.E(C) – 1/2(B.E))
V.E (C) = Valence electron in carbon atom of CBr4 molecule
L.E(C) = Lone pairs of an electron in the carbon atom of the CBr4 molecule.
B.E = Bond pair electron in C atom of CBr4 molecule
calculation of formal charge on carbon atom in CBr4 molecule

The carbon core atom (four single bonds connected to bromines) of the CBr4 molecule has four valence electrons, zero lone pair electrons, and eight bonding electrons. Put these values for the carbon atom in the formula above.

Formal charge on carbon atom of CBr4 molecule = (4- 0-(8/2)) =0

In the Lewis structure of CBr4, the formal charge on the central carbon atom is zero.

Summary:

In this post, we discussed the method to construct CBr4 Lewis Structure. Need to remember that, if you follow the above-said method, you can construct molecular dot structure very easily.