NBr3 Molecular Geometry - Science Education and Tutorials

Q: What is the molecular notation for NBr3 molecule?

NBr3 molecular notation is AX3N1.

Nitrogen tribromide(NBr3) has the composition of one nitrogen and three bromine atoms. What is the molecular geometry of Nitrogen tribromide?. Drawing and predicting the NBr3 molecular geometry is very easy by following the given method. Here in this post, we described step by step to construct NBr3 molecular geometry. Nitrogen and bromine come from the 15th and 17th family groups in the periodic table. Nitrogen and bromine have five and seven valence electrons respectively.

Table of Contents

Key Points To Consider When drawing The NBr3 Molecular Geometry

A three-step approach for drawing the NBr3 molecular can be used. The first step is to sketch the molecular geometry of the NBr3 molecule, to calculate the lone pairs of the electron in the central nitrogen atom; the second step is to calculate the NBr3 hybridization, and the third step is to give perfect notation for the NBr3 molecular geometry.

The NBr3 molecular geometry is a diagram that illustrates the number of valence electrons and bond electron pairs in the NBr3 molecule in a specific geometric manner. The geometry of the NBr3 molecule ion can then be predicted using the Valence Shell Electron Pair Repulsion Theory (VSEPR Theory) and molecular hybridization theory, which states that molecules will choose the NBr3 geometrical shape in which the electrons have from one another in the specific molecular structure.

Finally, you must add their bond polarities characteristics to compute the strength of the three N-Br single bonds (dipole moment properties of the NBr3 molecular geometry). Two nitrogen-bromine single bonds in the nitrogen tribromide(NBr3), for example, are polarised toward the more electronegative value bromine atoms, and because all three (N-Br) single bonds have the same size and polarity, their sum is nonzero due to the NBr3 molecule’s bond dipole moment due to pulling the electron cloud to the three side of trigonal pyramidal geometry, and the NBr3 molecule is classified as a polar molecule.

The molecule of nitrogen tribromide(with trigonal pyramidal shape NBr3 molecular geometry) is tilted at 101.5 degrees bond angle of Br-N-Br. It has a difference in electronegativity values between nitrogen and bromine atoms, with bromine’s pull the electron cloud being greater than nitrogen’s. But bond polarity of N-Br is not canceled to each other in the trigonal pyramidal geometry. As a result, it has a nonzero permanent dipole moment in its molecular structure. The NBr3 molecule has a nonzero dipole moment due to an unequal charge distribution of negative and positive charges in the trigonal pyramidal geometry.

Overview: NBr3 electron and molecular geometry

According to the VSEPR theory, the NBr3 molecule ion possesses trigonal pyramidal molecular geometry. Because the center atom, nitrogen, has three N-Br single bonds with the three bromine atoms surrounding it. The Br-N-Br bond angle is 101.5 degrees in the trigonal pyramidal NBr3 molecular geometry. The NBr3 molecule has a trigonal pyramidal geometry shape because it contains three bromine atoms in the geometry and four corners with one lone pair of electrons.

There are three N-Br single bonds at the NBr3 molecular geometry. After linking the three bromine atoms and one lone pair of electrons on the nitrogen atom in the trigonal pyramidal form, it maintains the pyramidal-shaped structure. In the NBr3 molecular geometry, the N-Br single bonds have stayed in the three terminals and one lone pair of electrons on the nitrogen atom of the trigonal pyramidal NBr3 molecule.

The center nitrogen atom of NBr3 has one lone pair of electrons, resulting in trigonal pyramidal NBr3 electron geometry. However, the molecular geometry of NBr3 looks trigonal pyramidal and has one lone pair of electrons on the nitrogen of the NBr3 geometry. It’s the NBr3 molecule’s symmetrical geometry. As a result, the NBr3 molecule is polar.

How to find NBr3 hybridization and molecular geometry

Calculating lone pairs of electrons on nitrogen in the NBr3 geometry:

Determine the number of lone pairs of electrons in the core nitrogen atom of the NBr3 Lewis structure. Because the lone pairs of electrons on the nitrogen atom are mostly responsible for the NBr3 molecule geometry planar, we need to calculate out how many there are on the central nitrogen atom of the NBr3 Lewis structure.

Use the formula below to find the lone pair on the nitrogen atom of the NBr3 molecule.
L.P(N) = V.E(N) – N.A(N-Br)/2

Lone pair on the central nitrogen atom in NBr3 = L.P(N)
The core central nitrogen atom’s valence electron in NBr3 = V.E(N)
Number of N-Br bonds = N.A (N-Br)
calculation for nitrogen atom lone pair in NBr3 molecule.

For instance of NBr3, the central atom, nitrogen, has five electrons in its outermost valence shell, three N-Br single bond connections. This gives a total of three connections.

As a result of this, L.P(P) = (5 –3)/2=1

The lone pair of electrons in the nitrogen atom of the NBr3 molecule is one.

Calculating lone pair of electrons on bromine in the NBr3 geometry:

Finding lone pair of electrons for the terminal bromine atom is not similar to the central nitrogen atom. We use the following formula as given below

Use the formula below to find the lone pair on the bromine atom of the NBr3 molecule.
L.P(Br) = V.E(Br) – N.A(N-Br)

Lone pair on the terminal bromine atom in NBr3= L.P(Br)
Terminal bromine atom’s valence electron in NBr3= V.E(Br)
Number of N-Br bonds = N.A ( N-Br)
calculation for bromine atom lone pair in NBr3 molecule.

For instance of NBr3, their terminal atoms, bromine, have seven electrons in their outermost valence shell, one N-Br single bond connection. This gives a total of three N-Br single bond connections. But we are considering only one connection for the calculation.

As a result of this, L.P(Br) = (7 –1)=6

The lone pair of electrons in the bromine atom of the NBr3 molecule is six. Three bromine atoms are connected with the central nitrogen atom.

In the NBr3 electron geometry structure, the lone pair on the central nitrogen atom is one, lone pairs of electrons in the bromine atom have six. Three bromine atoms have 18 lone pairs of electrons.

It means there are one lone pair of electrons in the core nitrogen atom. One lone pair of electrons on the central nitrogen atom is responsible for the trigonal pyramidal nature of NBr3 molecular geometry. But in the structure bromine atoms are polarised sidewise in their trigonal pyramidal geometry.

The one lone pair of electrons are placed at the top of the NBr3 geometry. Because the nitrogen atom is a lower electronegative value as compared with other atoms in the NBr3 molecule. Three bromine atoms are polarized towards the sidewise in the NBr3 structure.

But in reality, the NBr3 has one lone pair of electrons in its structure. This makes the NBr3 more asymmetrical in the structure of the molecule. Because there is electric repulsion between bond pairs and lone pairs. But some sort of interaction is there between bromine lone pairs and bond pairs. But it is negligible in the ground state.

But in the central, nitrogen atom has one lone pair of electrons and these lone pair electrons just oppose each other with nitrogen-bromine bond pairs.

Calculate the number of molecular hybridizations of the NBr3 molecule

What is NBr3 hybridization? This is a very fundamental question in the field of molecular chemistry. All the molecules are made of atoms. In chemistry, atoms are the fundamental particles. There are four different types of orbitals in chemistry. They are named s, p, d, and f orbitals.

The entire periodic table arrangement is based on these orbital theories. Atoms in the periodic table are classified as follows:

s- block elements
p- block elements
d-block elements
f-block elements
Atoms are classified in the periodic table

NBr3 molecule is made of one nitrogen, three bromine atoms. The bromine and nitrogen atoms have s and p orbitals. Bromine comes as the third element from the halogen family in the periodic table. The nitrogen atom also belongs to the nitrogen family group. But it falls as the first element in the periodic table.

When these atoms combine to form the NBr3 molecule, its atomic orbitals are mixed and form unique molecular orbitals due to hybridization.

How do you find the NBr3 molecule’s hybridization? We must now determine the molecular hybridization number of NBr3.

The formula of NBr3 molecular hybridization is as follows:
No. Hyb of NBr3= N.A(N-Br bonds) + L.P(N)
No. Hy of NBr3 = the number of hybridizations of NBr3
Number of N-Br bonds = N.A (N-Br bonds)
Lone pair on the central nitrogen atom = L.P(N)
Calculation for hybridization number for NBr3 molecule

In the NBr3 molecule, nitrogen is a core central atom with three bromine atoms connected to it. It has one lone pair of electrons on nitrogen. The number of NBr3 hybridizations (No. Hyb of NBr3) can then be estimated using the formula below.

No. Hyb of NBr3= 3+1=4

The NBr3 molecule ion hybridization is four. The nitrogen and bromine atoms have s and p orbitals. The sp3 hybridization of the NBr3 molecule is formed when one s orbital and three p orbitals join together to form the NBr3 molecular orbital.

Molecular Geometry Notation for NBr3 Molecule :

Determine the form of NBr3 molecular geometry using VSEPR theory. The AXN technique is commonly used when the VSEPR theory is used to calculate the shape of the NBr3 molecule.

The AXN notation of NBr3 molecule is as follows:
The central nitrogen atom in the NBr3 molecule is denoted by the letter A.
The bound pairs (three N-Br bonds) of electrons to the core nitrogen atom are represented by X.
The lone pairs of electrons on the central nitrogen atom are denoted by the letter N.
Notation for NBr3 molecular geometry

We know that nitrogen is the core atom, with two electron pairs bound (three N-Br) and one lone pair of electrons. The general molecular geometry formula for NBr3 is AX3N1.

According to the VSEPR theory, if the NBr3 molecule ion has an AX3N1 generic formula, the molecular geometry and electron geometry will both be trigonal pyramidal forms.

Name of Molecule	nitrogen tribromide
Chemical molecular formula	NBr3
Molecular geometry of NBr3	Trigonal pyramidal
Electron geometry of NBr3	Trigonal pyramidal
Hybridization of NBr3	sp3
Bond angle (Br-N-Br)	101.5º degree
Total Valence electron for NBr3	26
The formal charge of NBr3 on nitrogen	0

Summary:

In this post, we discussed the method to construct NBr3 molecular geometry, the method to find the lone pairs of electrons in the central nitrogen atom, NBr3 hybridization, and NBr3 molecular notation. Need to remember that, if you follow the above-said method, you can construct the NBr3 molecular structure very easily.