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Mastering the Lewis Structure and Formal Charges of BBr3

How to Draw the Lewis Structure for BBr3The Lewis structure for BBr3 is a crucial concept to understand for chemistry students. It is used to depict the bonding of three bromine atoms to a central boron atom.

By knowing how to draw the Lewis structure for BBr3, one can understand the molecule’s valence electrons and identify how many bonds it should form to be stable. In this article, we will discuss the Lewis structure for BBr3 and explain how to draw it step-by-step.

Valence Electrons

Valence electrons are electrons that are located in the outermost shell of an atom. These electrons are crucial in determining how an atom will bond with other atoms to form a molecule.

The valence electrons of boron and bromine are important in drawing the Lewis structure for BBr3. Boron has three valence electrons, while bromine has seven valence electrons.

When we add up the valence electrons for each bromine atom (7 electrons x 3 atoms) and boron (3 electrons), the total number of valence electrons in BBr3 is 24.

Placement of Least Electronegative Atom

In the Lewis structure for BBr3, we first place the boron atom in the central position because it is the least electronegative atom in the molecule. Electronegativity is the ability of an atom to attract electrons towards itself in a covalent bond.

As boron is the least electronegative atom in BBr3, it is best suited to be placed in the central position.

Bonding Outer Atoms to Central Atom

After placing the boron atom in the central position, the next step in drawing the Lewis structure for BBr3 is to bond the outer atoms to the central atom. In this case, we bond each of the three bromine atoms to the central boron atom using a single bond.

A single bond is represented by a line that connects two atoms to form a covalent bond.

Placing Remaining Electrons on Outer Atoms

Once we have bonded the outer atoms to the central atom, we then place the remaining valence electrons on the outer atoms. Since each bromine atom has seven valence electrons and has formed a single bond with the central boron atom, each bromine atom is short of one electron to complete its octet (having eight electrons).

To complete the octet of each bromine atom, we place one electron on each bromine atom in the form of a dot. By doing this, each bromine atom will now have eight electrons, which makes it stable.

We continue this process until each bromine atom has eight electrons around it.

Completing Octet of Central Atom

The final step in drawing the Lewis structure for BBr3 is to complete the octet of the central boron atom. As seen in the previous steps, the boron atom has formed three single bonds with the bromine atoms, which means it has used up six of its valence electrons.

To complete its octet, the boron atom must use its remaining two valence electrons. We place the remaining two valence electrons of boron as dots on the central atom.

Doing so completes the octet of the central boron atom, making the entire BBr3 molecule stable.

Conclusion

In conclusion, drawing the Lewis structure for BBr3 is a crucial concept in chemistry. The valence electrons of boron and bromine, along with the placement of the least electronegative atom, bonding the outer atoms to the central atom, placing the remaining electrons on outer atoms, and completing the octet of the central atom, are all vital steps in the process.

By understanding how to draw the Lewis structure for BBr3, one can identify the bonding within the molecule and predict its chemical properties. It is essential to master this skill to excel in chemistry and related fields.

The Formal Charge Concept for BBr3

In chemistry, the concept of formal charge is an important tool used to predict the stability of a molecule. Formal charges provide information about the distribution of electrons within the molecule and help identify which atoms are more likely to form bonds.

In this article, we will discuss the formal charge concept for BBr3 and explain how to determine the formal charges in each atom.

Determining Stability Using Formal Charge

The formal charge of an atom in a molecule is the difference between the number of valence electrons on the atom in the free state and the number of electrons assigned to that atom in the molecule. By calculating the formal charge on each atom in the molecule, we can determine which atoms have gained or lost electrons and how they contribute to the molecule’s stability.

In BBr3, the boron atom has three valence electrons, and each bromine atom has seven valence electrons. When we subtract the number of electrons assigned to each atom in the molecule from the number of valence electrons on the atom in the free state, we obtain the formal charge.

Formal Charge on Bromine

To find the formal charge on a bromine atom in BBr3, we need to subtract the number of electrons assigned to the bromine atom from the number of valence electrons in bromine. Each bromine atom in BBr3 has seven valence electrons and has formed one single bond with the central boron atom.

In this case, one bonding pair of electrons is shared between the bromine atom and boron atom, and the remaining six electrons are placed on the bromine atom to complete its octet. Thus, the formal charge on each bromine atom in BBr3 is:

[(Number of valence electrons in bromine) – (Number of lone pair electrons on bromine) – (Number of bonding electrons on bromine)]

= [7 – 6 – 1]

= 0

The formal charge on each bromine atom is zero, indicating that it has retained all of its valence electrons.

This means that each bromine atom in BBr3 is stable.

Formal Charge on Boron

To calculate the formal charge on the boron atom in BBr3, we must subtract the number of assigned electrons from the number of valence electrons of boron. In this case, the boron atom has formed three single bonds with the three bromine atoms, which is a total of three bonding pairs of electrons.

The remaining electrons on the boron atom are in the form of one lone pair of electrons. Thus, the formal charge on the boron atom in BBr3 is:

[(Number of valence electrons in boron) – (Number of lone pair electrons on boron) – (Number of bonding electrons on boron)]

= [3 – 2 – 6]

= -5

The formal charge on the boron atom in BBr3 is negative, indicating that it has received more electrons than it should have in its most stable structure.

A formal charge of -5 indicates that boron does not have a complete octet. This may lead one to believe that the molecule is unstable.

However, in the case of BBr3, the boron atom can sustain a formal charge of -5 because it is compensated by the formal charges on the surrounding bromine atoms, making the molecule stable.

Conclusion

In conclusion, understanding the formal charge concept is essential for determining the stability of a molecule. In BBr3, we have calculated the formal charges of each bromine and boron atoms.

The formal charge on each bromine atom in BBr3 is zero, indicating that the bromine atoms are stable. However, the formal charge on boron atom in BBr3 is negative, indicating that it has an incomplete octet.

This may seem like the molecule is unstable but in reality, a formal charge of -5 on boron is compensated by the formal charges on the surrounding bromine atoms, making the molecule stable. In conclusion, the formal charge concept is a crucial tool in predicting the stability of a molecule.

By understanding the formal charges on each atom in BBr3, we can identify the bonding within the molecule and determine its stability. The formal charges on each bromine atom in BBr3 are zero, making each atom stable, while the formal charge on boron is negative due to the incomplete octet.

However, this is compensated for by the formal charges on the surrounding bromine atoms. The formal charge concept is essential for excelling in chemistry and related fields, and it aids in predicting chemical properties of molecules.

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