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How to draw NH3 Lewis Structure? - Science Education and Tutorials

# How to draw NH3 Lewis Structure?

Drawing NH3 Lewis Structure is very easy to by using the following method. Here in this post, we described step by step method to construct NH3 Lewis Structure.

## Key Points To Consider When Drawing The NH3 Structure

A three-step approach for drawing the NH3 Lewis structure can be used. The first step is to sketch the Lewis structure of the NH3 molecule, to add valence electrons around the nitrogen atom; the second step is to add valence electrons to the three hydrogen atoms, and the final step is to combine the step1 and step2 to get the NH3 Lewis Structure.

The NH3 Lewis structure is a diagram that illustrates the number of valence electrons and bond electron pairs in the NH3 molecule. The geometry of the NH3 molecule can then be predicted using the Valence Shell Electron Pair Repulsion Theory (VSEPR Theory), which states that molecules will choose the NH3 geometrical shape in which the electrons have from one another.

Finally, you must add their bond polarities to compute the strength of the N-H bond (dipole moment properties of the NH3 molecule). The nitrogen-hydrogen bonds in ammonia(NH3), for example, are polarised toward the more electronegative nitrogen, and because both bonds have the same size and located around four terminals with one lone pair of electrons and three hydrogen atoms, their sum is non zero due to the NH3 molecule’s bond dipole moment and one lone pair of electron on the nitrogen atom. The ammonia molecule is classified as a polar molecule.

The molecule of ammonia (with tetrahedral molecular geometry) is tilted, the bond angles between nitrogen and hydrogen are 107 degrees. It has a difference in electronegativity values between nitrogen and hydrogen atoms, with nitrogen’s pull being less than hydrogen’s terminal in the NH3 molecule. As a result, it has the permanent dipole moment. The NH3 molecule has a permanent dipole moment due to an unequal charge distribution of negative and positive charges. The net dipole moment of the NH3 molecule is 1.4 D.

## NH3 Lewis Structure: point to remember

The central atom is nitrogen, which is bordered on four terminals with three hydrogen atoms(downwards in tetrahedral geometry), and one lone pair on the nitrogen in the top of the tetrahedral geometry. Nitrogen has five outermost valence electrons, indicating that it possesses five electrons in its outermost shell, whereas hydrogen only has one valence electron in its outermost shell. To complete the octet of the nitrogen atom, a nitrogen central atom requires three valence electrons. If you’re interested in learning more about the nitrogen octet rule, please see in our previous post.

Three hydrogen atoms establish covalent connections with the central nitrogen atom as a result, leaving the nitrogen atom with one lone pair. There is one lone pair on the nitrogen central atom that resist the bond pairs of the three N-H. According to VSEPR theory, the electronic repulsion of the lone pair and bond pair leads the NH3 molecule to take on a tetrahedral molecular geometry shape.

The NH3 molecule’s N-H bonds are arranged in asymmetrical order around the tetrahedral molecular geometry, giving rise to the NH3 molecular shape. The NH3 molecule has a tetrahedral molecular geometry because there is electrical repulsion between one lone pair and three bond pairs(N-H) of the NH3 molecule.

### Electronegative Difference Calculation of NH3 Molecule:

The nitrogen atom has an electronegativity of 3.04, while hydrogen has an electronegativity of 2.20 in the NH3 molecule. The difference in electronegativity can be estimated using the method below.

The electronegative value difference between nitrogen and hydrogen

Electronegativity value of nitrogen = 3.04

Electronegativity value of hydrogen= 2.20

Difference of electronegativity value between nitrogen and hydrogen= 3.04 – 2.20 =0.84

Electronegativity difference between N-H bond calculation of NH3 molecule

Due to the difference in electronegativity value of greater than 0.5, the N-H bond of the NH3 molecule becomes polar. Because of this difference in electronegativity, the NH3 molecule’s N-H bond becomes polar. The electronegativity of an atom is the strength with which it may attract bound electron pairs to its side. The polarity of NH3 is discussed in our previous post.

As a result, the N-H bond’s dipole moment is high due to the polarization of the bonds and one lone pair of electrons, and all N-H bonds’ dipoles are arranged in the tetrahedral molecular geometry. The NH3 molecule’s total dipole moment is predicted to be 1.4 D. It has a partial negative charge for the nitrogen atom and a partial positive charge for the terminal hydrogen atoms.

The electron dot structure of the NH3 molecule is also known as the NH3 Lewis structure. It determines the number of outermost valence electrons as well as the electrons engaged in the NH3 molecule’s bond formation. The outermost valence electrons of the NH3 molecule must be understood while considering the Lewis structure of the molecule.

The nitrogen atom is the middle element in NH3 molecular geometry, with five electrons in its outermost valence electron shell, whereas the hydrogen atom has one electron in its outermost valence electron shell.

The NH3 molecule has a total of 8 valence electrons as a result of the foregoing above said reasoning. With the core central nitrogen atom, the four terminal with three hydrogen atoms forms covalent bonds, leaving the nitrogen atom with one lone pair on the top of tetrahedral geometry.

The tetrahedral molecular geometry and structure of the NH3 molecules are similar to that of the methane (CH4) molecule. Because one lone pair of a central nitrogen atom create interaction with N-H bond pairs. The bond angle of the H-N-H bond in the tetrahedral molecular geometry is approximately 107 degrees. This angle is less than the CH4 molecule bond angle due to the one lone pair of electrons on the NH3 molecule. The N-H bond length is 100 pm(picometer) respectively.

## To sketch the NH3 Lewis structure by following these instructions:

### Step-1: NH3 Lewis dot Structure by counting valence electrons on the nitrogen atom

To calculate the valence electron of each atom in NH3, look for its periodic group from the periodic table. The nitrogen and hydrogen families, which are the 15th and 1st groups in the periodic table, are both made up of nitrogen and hydrogen atoms. In their outermost shells, nitrogen and hydrogen have five and one valence electrons, respectively.

Because nitrogen and hydrogen are members of the periodic table’s nitrogen and hydrogen family groups, their valence electrons are five and one, respectively.

Calculate the total number of valence electrons in the NH3 molecule’s outermost valence shell. The first step is to determine how many electrons are in the NH3 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 NH3 Lewis diagram. The NH3 molecule’s core nitrogen atom can be represented as follows:

Total outermost valence shell electron of nitrogen atom in NH3= 5

Total outermost valence shell electron of the hydrogen atom in NH3= 1

The NH3 molecule has one central nitrogen and three hydrogen atoms. Then the total outermost valence shell electrons can be calculated as follows

∴ Total outermost valence shell electrons available for NH3 Lewis structure( dot structure) = 5+3*1= 8 valence electrons  in NH3.

calculation of total valence electron of NH3 molecule

Choose the atom with the least electronegative value atom and insert it in the center of the molecular geometry of NH3. We’ll choose the least electronegative value atom in the NH3 molecule to place in the center of the NH3 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 NH3 for constructing around the central nitrogen atom

As a result, nitrogen is the first atom in the periodic table’s nitrogen family group. Hydrogen is the first member of the hydrogen family. The electronegative value of the nitrogen atom is lower than that of the hydrogen atom in the NH3 molecule. Furthermore, nitrogen has a five electrons limit since nitrogen is the most electronegative element in the NH3 molecule.

In the NH3 Lewis structure diagram, the nitrogen atom can be the center atom of the molecule. As a result, central nitrogen in the NH3 Lewis structure, with all three hydrogens arranged in the tetrahedral geometry.

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

### Step-3: Lewis dot Structure for NH3 generated from step-1 and step-2

Connect the exterior and core central atom of the NH3 molecule with three single bonds (N-H). In this stage, use three hydrogen atoms on the outside of the NH3 molecule to the central nitrogen atom in the middle.

Count how many electrons from the outermost valence shell have been used in the NH3 structure so far. Each N-H bond carries two electrons because each nitrogen atom is connected to three hydrogen atoms by three N-H bonds. Bond pairings of N-H are what they’re called.

So, out of the total of 8 valence electrons available for the NH3 Lewis structure, we used 6 for the NH3 molecule’s three N-H bonds. The NH3 molecule has one lone pair electron in the center of nitrogen. We need to put no extra electrons in the molecular geometry of NH3.

Place the valence electrons in the N-H bond pairs starting with the core nitrogen, three hydrogens, and one lone pair of electrons in the NH3 molecule. In the NH3 Lewis structure diagram, we always begin by introducing valence electrons from the central nitrogen atom(in step1). As a result, wrap around the central nitrogen atom’s bond pair valence electrons first (see figure for step1).

Nitrogen requires 6 electrons in its outermost valence shell to complete the molecular stability, 6 electrons bond pairs in N-H bonds. Then two electrons as a lone pair of electrons on the nitrogen atom of the NH3 molecule are placed in a tetrahedral geometry. Nitrogen already shares 6 electrons to the three N-H bonds. Then place the valence electron in the hydrogen atom, it placed around one electron(step-2). Totally, 3 valence electrons placed on the three hydrogen atoms of the NH3 molecule.

We’ve positioned 6 electrons around the central nitrogen atom(step-3), which is represented by a dot, in the NH3 molecular structure above. The nitrogen atom completes its molecular stability in the NH3 molecule because it possesses 6 electrons in its bond pairs with three hydrogens in the outermost valence shell.

Count how many outermost valence shell electrons have been used so far using the NH3 Lewis structure. Three electron bond pairs are shown as dots in the NH3 chemical structure, whereas three single bonds each contain two electrons. The outermost valence shell electrons of the NH3 molecule are six as a result of the calculation.

So far, we’ve used six of the NH3 Lewis structure’s total 8 outermost valence shell electrons. one lone pair of electrons on the nitrogen atom in the tetrahedral geometry of the NH3 molecule.

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

The core atom in the NH3 Lewis structure is nitrogen, which is bonded to the three hydrogen atoms by single bonds (N-H). With the help of three single bonds, it already shares six electrons. As a result, nitrogen follows the octet rule and has eight electrons surrounding it on the three terminals of the NH3 molecule’s tetrahedral geometry.

## How to calculate the formal charge on a nitrogen atom in NH3 Lewis Structure?

The formal charge on the NH3 molecule’s nitrogen central atom often corresponds to the actual charge on that nitrogen central atom. In the following computation, the formal charge will be calculated on the central nitrogen atom of the NH3 Lewis dot structure.

To calculate the formal charge on the central nitrogen atom of the NH3 molecule by using the following formula:

The formal charge on the nitrogen atom of NH3 molecule= (V. E(N)– L.E(N) – 1/2(B.E))

V.E (C) = Valence electron in a nitrogen atom of NH3 molecule

L.E(C) = Lone pairs of an electron in the nitrogen atom of the NH3 molecule.

B.E = Bond pair electron in N atom of NH3 molecule

calculation of formal charge on nitrogen atom in NH3 molecule

The nitrogen core atom (three single bonds connected to three hydrogen atoms ) of the NH3 molecule has five valence electrons, one lone pair of electrons(two electrons), and six bonding electrons. Put these values for the nitrogen atom in the formula above.

Formal charge on nitrogen atom of NH3 molecule = (5- 2-(6/2)) =0

In the Lewis structure of NH3, the formal charge on the central nitrogen atom is zero.

## Summary:

In this post, we discussed the method to construct the NH3 Lewis structure. Need to remember that, if you follow above said method, you can construct molecular dot structure very easily.

## What is the NH3 Lewis structure?

NH3 Lewis structure is dot representation

## What is the formal charge on the NH3 Lewis structure?

Zero charge on the NH3 molecular structure

## The polarity of the molecules

Polarity of the molecules are listed as follows

## Lewis Structure and Molecular Geometry

Lewis structure and molecular geometry of molecules are listed below

## External Reference:

Information on NH3

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