How to draw CH2Br2 Lewis Structure? - Science Education and Tutorials

The dibromomethane chemical formula is CH2Br2. Drawing CH2Br2 Lewis Structure is very easy to by using the following method. Here in this post, we described step by step method to construct CH2Br2 Lewis Structure. The carbon, bromine, and hydrogen elements come as the member of the carbon, halogen, and hydrogen family groups from the periodic table respectively. The valence electrons in carbon, bromine, and hydrogen are four, seven, and one respectively. Iodomethane is used as an volatile organic solvent in organic reactions.

Table of Contents

Key Points To Consider When Drawing The CH2Br2 Structure

A three-step approach for drawing the CH2Br2 Lewis structure can be used. The first step is to sketch the Lewis structure of the CH2Br2 molecule, to add valence electron around the carbon atom; the second step is to add valence electrons to the two bromine and two hydrogen atoms, and the final step is to combine the step1 and step2 to get the CH2Br2 Lewis Structure.

The CH2Br2 Lewis structure is a diagram that illustrates the number of valence electrons and bond electron pairs in the CH2Br2 molecule. The geometry of the CH2Br2 molecule can then be predicted using the Valence Shell Electron Pair Repulsion Theory (VSEPR Theory), which states that molecules will choose the CH2Br2 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 CH2Br2 molecule). The carbon-bromine bonds in dibromothane(CH2Br2), for example, are polarised toward the more electronegative bromine, and because both bonds have the same size and located around four terminals with two bromine and two hydrogen atoms, their sum is non zero due to the CH2Br2 molecule’s bond dipole moment and the lone pairs of electron on two bromine atoms. The CH2Br2 molecule is classified as a polar molecule.

The molecule of dibromomethane (with tetrahedral molecular geometry) is tilted, the bond angles between bromine, carbon, and hydrogen(H-C-H and Br-C-Br) are 112.5 and 113.4 degrees. It has a difference in electronegativity values between carbon and bromine atoms, with carbon’s pull being less than bromine’s terminal in the CH2Br2 molecule. As a result, it has the permanent dipole moment. The CH2Br2 molecule has a permanent dipole moment due to an unequal charge distribution of negative and positive charges. The net dipole moment of the CH2Br2 molecule is lower than the dipole moment of the CH2F2 molecule.

CH2Br2 Lewis Structure:

The central atom is carbon, which is bordered on four terminals with two bromine atoms, two hydrogen atoms, and no lone pair on the carbon in the tetrahedral geometry. Carbon has four outermost valence electrons, indicating that it possesses four electrons in its outermost shell, whereas bromine only has seven valence electrons in its outermost shell. To complete the octet of the bromine atom, a bromine terminal atom requires one electron. If you’re interested in learning more about the bromine octet rule, please see in our previous post.

Two bromine and two hydrogen atoms establish covalent connections with the central carbon atom as a result, leaving the carbon atom with no lone pair. There is no lone pair on the carbon central atom that resist the bond pairs of the two C-Br and C-H. According to VSEPR theory, no electronic repulsion of the lone pair and bond pair leads the CH2Br2 molecule to take on a tetrahedral molecular geometry shape.

The CH2Br2 molecule’s C-Br bonds are arranged in asymmetrical order around the tetrahedral molecular geometry, giving rise to the CH2Br2 molecular shape. The CH2Br2 molecule has a tetrahedral molecular geometry because there is no electrical repulsion between lone pair and bond pairs of CH2Br2 molecule.

Electronegative Difference Calculation of CH2Br2 Molecule:

The carbon atom has an electronegativity of 2.55, while bromine has an electronegativity of 2.96 in the CH2Br2 molecule. The difference in electronegativity can be estimated using the method below.

The electronegative value difference between carbon and bromine
Electronegativity value of carbon = 2.55
Electronegativity value of bromine = 2.96
Difference of electronegativity value between carbon and bromine = 2.96 – 2.55 = 0.41
Electronegativity difference between C-Br bond calculation of CH2Br2 molecule

The electronegative value difference between carbon and hydrogen
Electronegativity value of carbon = 2.55
Electronegativity value of hydrogen= 2.20
Difference of electronegativity value between carbon and hydrogen= 2.55 – 2.20 =0.35
Electronegativity difference between C-H bond calculation of CH2Br2 molecule

Due to the difference in electronegativity value of less than 0.5, the C-Br bond of the CH2Br2 molecule becomes less polar. Because of this difference in electronegativity, the CH2Br2 molecule’s C-Br bond becomes slightly polar. The electronegativity of an atom is the strength with which it may attract bound electron pairs to its side. The polarity of CH2Br2 is discussed in our previous post.

As a result, the C-Br bond’s dipole moment is high due to the polarization of the bonds, and all C-Br bonds’ dipoles are arranged in the tetrahedral molecular geometry. The CH2Br2 molecule’s total dipole moment is predicted to be less than the CH2Br2 molecule. It has a partial negative charge for bromine atoms and a partial positive charge for the central carbon atom.

The electron dot structure of the CH2Br2 molecule is also known as the CH2Br2 Lewis structure. It determines the number of outermost valence electrons as well as the electrons engaged in the CH2Br2 molecule’s bond formation. The outermost valence electrons of the CH2Br2 molecule must be understood while considering the Lewis structure of the molecule.

The carbon atom is the middle element in CH2Br2 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 CH2Br2 molecule has a total of 20 valence electrons as a result of the foregoing above said reasoning. With the core central carbon atom, the four terminal with two bromine and two hydrogen atoms form covalent bonds, leaving the carbon atom with no lone pairs on it.

The tetrahedral molecular geometry and structure of the CH2Br2 molecules are similar to that of the methane (CH4) molecule. Because no lone pair of a central carbon atom create interaction with C-Br bond pairs. The bond angle of the Br-C-Br and H-C-H in the tetrahedral molecular geometry is approximately 113.4 and 112.5 degrees. The C-Br and C-H bond lengths are 191 and 107 pm(picometer) respectively.

To sketch the CH2Br2 Lewis structure by following these instructions:

Step-1: CH2Br2 Lewis dot Structure by counting valence electron

To calculate the valence electron of each atom in CH2Br2, look for its periodic group from the periodic table. The carbon and halogen families, which are the 14th and 17th 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.

Calculate the total number of valence electrons in the CH2Br2 molecule’s outermost valence shell. The first step is to determine how many electrons are in the CH2Br2 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 CH2Br2 Lewis diagram. The CH2Br2 molecule’s core carbon atom can be represented as follows:

Total outermost valence shell electron of carbon atom in CH2Br2= 4
Total outermost valence shell electron of the bromine atom in CH2Br2= 7
The CH2Br2 molecule has one central carbon, two hydrogen, and two bromine atoms. Then the total outermost valence shell electrons can be calculated as follows
∴ Total outermost valence shell electrons available for CH2Br2 Lewis structure( dot structure) = 4 +2*7+ 2*1= 20 valence electrons in CH2Br2
calculation of total valence electron of CH2Br2 molecule

Choose the atom with the least electronegative value atom and insert it in the center of the molecular geometry of CH2Br2. We’ll choose the least electronegative value atom in the CH2Br2 molecule to place in the center of the CH2Br2 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: Lewis Structure of CH2Br2 for constructing around the more electronegative atom

As a result, carbon is the first atom in the periodic table’s carbon family group. Bromine is the third member of the halogen family. The electronegative value of the carbon atom is lower than that of the bromine atom in the CH2Br2 molecule. Furthermore, carbon has a four electrons limit since bromine is the most electronegative element in the CH2Br2 molecule.

In the CH2Br2 Lewis structure diagram, the carbon atom can be the center atom of the molecule. As a result, central carbon in the CH2Br2 Lewis structure, with all two bromine and two hydrogens arranged in the tetrahedral geometry.

Add valence electrons around the bromine atom and add valence hydrogen atom, as given in the figure.

Step-3: Lewis dot Structure for CH2Br2 generated from step-1 and step-2

Connect the exterior and core central atom of the CH2Br2 molecule with four single bonds (two C-Br and C-H). In this stage, use four single bonds to connect all two bromine and two hydrogen atoms on the outside of the CH2Br2 molecule to the central carbon atom in the middle.

Count how many electrons from the outermost valence shell have been used in the CH2Br2 structure so far. Each C-Br bond carries two electrons because each carbon atom is connected to two bromine and two hydrogen atoms by two C-Br and C-H bonds. Bond pairings of C-Br and C-H are what they’re called.

So, out of the total of 20 valence electrons available for the CH2Br2 Lewis structure, we used 8 for the CH2Br2 molecule’s two C-Br and C-H bonds. The CH2Br2 molecule has no lone pair electron in the center of carbon. We need to put no extra electrons in the molecular geometry of CH2Br2.

Place the valence electrons in the C-H and C-Br bond pairs starting with the core carbon, two hydrogen, and two bromine atoms in the CH2Br2 molecule. In the CH2Br2 Lewis structure diagram, we always begin by introducing valence electrons from the central carbon atom(in step1). As a result, wrap around the central carbon atom’s bond pair valence electrons first (see figure for step1).

Carbon requires 8 electrons in its outermost valence shell to complete the molecular stability, 8 electrons bond pairs in C-H and C-Br bonds. Then place no electrons as a lone pair of electrons on the carbon atom of the CH2Br2 molecule. Carbon already shares 8 electrons to the four single C-Br and C-H bonds. Then place the valence electron in the bromine atom, it placed around seven electrons(step-2). Totally, 12 valence electrons placed on the two bromine atoms of the CH2Br2 molecule.

We’ve positioned 8 electrons around the central carbon atom(step-3), which is represented by a dot, in the CH2Br2 molecular structure above. The carbon atom completes its molecular stability in the CH2Br2 molecule because it possesses 8 electrons in its bond pairs with two bromine and two hydrogens in the outermost valence shell.

Count how many outermost valence shell electrons have been used so far using the CH2Br2 Lewis structure. Four electron bond pairs are shown as dots in the CH2Br2 chemical structure, whereas four single bonds each contain two electrons. The outermost valence shell electrons of the CH2Br2 molecule are 8 +12 = 20 as a result of the calculation.

So far, we’ve used 20 of the CH2Br2 Lewis structure’s total 20 outermost valence shell electrons. No lone pair of electrons on the carbon atom in the tetrahedral geometry of the CH2Br2 molecule.

Complete the middle carbon atom stability and, if necessary, apply a covalent bond. The central carbon atom undergoes octet stability. Because it has a total of eight electrons in the outermost valence shell.

The core atom in the CH2Br2 Lewis structure is carbon, which is bonded to the bromine and hydrogen atoms by four single bonds (C-Br and C-H). With the help of four single bonds, it already shares eight electrons. As a result, bromine follows the octet rule and has eight electrons surrounding it on the two terminals of the CH2Br2 molecule’s tetrahedral geometry.

How to calculate the formal charge on a carbon atom in CH2Br2 Lewis Structure?

The formal charge on the CH2Br2 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 CH2Br2 Lewis dot structure.

To calculate the formal charge on the central carbon atom of the CH2Br2 molecule by using the following formula:
The formal charge on the carbon atom of CH2Br2 molecule= (V. E(C)– L.E(C) – 1/2(B.E))
V.E (C) = Valence electron in a carbon atom of CH2Br2molecule
L.E(C) = Lone pairs of an electron in the carbon atom of the CH2Br2 molecule.
B.E = Bond pair electron in C atom of CH2Br2 molecule
calculation of formal charge on carbon atom in CH2Br2 molecule

The carbon core atom (four single bonds connected to two bromine and two hydrogen atoms ) of the CH2Br2 molecule has four valence electrons, no lone pair of electrons, and eight bonding electrons. Put these values for the carbon atom in the formula above.

Formal charge on carbon atom of CH2Br2 molecule = (4- 0-(8/2)) =0

In the Lewis structure of CH2Br2, the formal charge on the central carbon atom is zero.

Summary:

In this post, we discussed the method to construct the CH2Br2 Lewis structure. Need to remember that, if you follow above said method, you can construct molecular dot structure very easily.