How to draw AsCl3 Lewis Structure? - Science Education and Tutorials

Q: What is the formal charge on the AsCl3 Lewis structure?

Zero charges on the AsCl3 molecular structure

The Arsenic trichloride chemical formula is AsCl3. DrawingAsCl3 Lewis Structure is very easy to by using the following method. Here in this post, we described step by step method to construct AsCl3 Lewis Structure. The Arsenic and chlorine elements come as members of the nitrogen and halogen family groups from the periodic table respectively. The valence electrons in Arsenic and chlorine are five and seven respectively. The branch of Arsenic halogen compound chemistry is used to make chemicals reagents for organic chemical reactions.

Table of Contents

Key Points To Consider When Drawing The AsCl3 Electron Dot Structure

A three-step approach for drawing the AsCl3 Lewis structure can be used. The first step is to sketch the Lewis structure of the AsCl3 molecule, to add valence electrons around the Arsenic atom; the second step is to add valence electrons to the three chlorine atoms, and the final step is to combine the step1 and step2 to get the AsCl3 Lewis Structure.

The AsCl3 Lewis structure is a diagram that illustrates the number of valence electrons and bond electron pairs in the AsCl3 molecule. The geometry of the AsCl3 molecule can then be predicted using the Valence Shell Electron Pair Repulsion Theory (VSEPR Theory), which states that molecules will choose the AsCl3 geometrical shape in which the electrons have from one another.

Finally, you must add their bond polarities to compute the strength of the three As-Cl single bonds (dipole moment properties of the AsCl3 molecule). The Arsenic-chlorine bonds in Arsenic trichloride(AsCl3), for example, are polarised toward the more electronegative chlorine in AsCl3 molecule, and because both bonds have the same size and are located around three chlorine terminals of the trigonal pyramidal with one lone pair (in total two electrons) on the Arsenic atom, their sum of dipole moment is nonzero due to the AsCl3 molecule’s bond dipole moment and more electron polarity to the chlorine atoms. Because each three As-Cl bonds polarity not canceled each other in the AsCl3 molecule due to the presence of one lone pair of electrons. The Arsenic trichloride(AsCl3) molecule is classified as a polar molecule.

The molecule of Arsenic trichloride (with trigonal pyramidal molecular geometry) is tilted, the bond angles between Arsenic and chlorine are 100 degrees. It has a difference in electronegativity values between Arsenic and chlorine atoms, with central Arsenic’s pull being less than terminal chlorine’s in the AsCl3 molecule. But they not canceled each other due to the asymmetrical trigonal pyramidal with one lone pair in the molecular geometry of the AsCl3 molecule.

As a result, it has the nonzero dipole moment. The AsCl3 molecule has a nonzero dipole moment due to an unequal charge distribution of negative and positive charges. But both Arsenic and chlorine atoms fall on the nitrogen and halogen family groups in the periodic table respectively. The chlorine atom is a more electronegative value than Arsenic in the AsCl3 molecule. The AsCl3 molecule has the net dipole moment of 2.17D value in the ground state energy state.

AsCl3 molecule has three As-Cl single bonds. Its dipole moment in the ground state is totally different as compared with the excited state. If it absorbs light may be from visible or UV light. It undergoes pi to pi star and n to pi star transition from ground state energy level to excited state energy level. In the excited state energy level, the AsCl3 molecule shows a definite dipole moment. But it is very dynamics.

Molecules can be classified as polar or nonpolar. The molecule polar behaves in a different manner as compared to nonpolar.

Overview: AsCl3 Lewis Structure

The central atom is Arsenic, which is bordered on three terminals with chlorine atoms( in trigonal pyramidal geometry), and one lone pair on the central Arsenic atom in the trigonal pyramidal molecular geometry. Arsenic has five outermost valence electrons, indicating that it possesses five electrons in its outermost shell, whereas chlorine also has seven valence electrons in its outermost shell. To complete the octet of the Arsenic and chlorine atoms requires three and one valence electrons on each of their outermost shell respectively.

Three chlorine atoms establish covalent connections with the central Arsenic atom as a result, leaving the Arsenic atom with one lone pair. There is one lone pair of electrons on the Arsenic central atom that resists the bond pairs of the three As-Cl bonds. According to VSEPR theory, the single As-Cl bond pairs polarity lead the AsCl3 molecule to take on the trigonal pyramidal geometry structure.

The AsCl3 molecule’s three As-Cl bonds are arranged in symmetrical polarity order around the trigonal pyramidal molecular geometry, giving rise to the AsCl3 molecular shape. The AsCl3 molecule has a trigonal pyramidal molecular geometry because there is an electrical repulsion between the lone pairs of electrons in Arsenic and three single bond pairs(As-Cl) of the AsCl3 molecule.

Lewis structure of AsCl3 has dot electron representative structure. Valence electrons of atoms undergo orbitals mixing in the chemical reactions, gives new types of molecular species of AsCl3. The molecule is nothing but a bundle of valence electrons from the atoms. But it is converted to bond pairs and lone pairs in the molecular structure.

Electronegative value Difference Calculation of AsCl3 Molecule:

Arsenic and chlorine Electronegative difference in AsCl3:

The Arsenic atom has an electronegativity of 2.19, while chlorine has an electronegativity of 3.16 in the AsCl3 molecule. The difference in electronegativity of Arsenic and chlorine can be estimated using the method below.

The electronegative value difference between Arsenic and chlorine in AsCl3 molecule
Electronegativity value of Arsenic = 2.19
Electronegativity value of chlorine= 3.16
Difference of electronegativity value between Arsenic and chlorine in AsCl3 molecule = 3.16 – 2.19 = 0.97
Electronegativity difference between As-Cl bond calculation of AsCl3 molecule

The electronegative difference between Arsenic and chlorine is greater than 0.5. This indicated the bond polarity moves near to polar nature. As-Cl bond polarity in the AsCl3 molecule is polar.

Because of this difference in electronegativity of Arsenic and chlorine atoms, the AsCl3 molecule’s As-Cl bond becomes polar. The total net dipole moment of the AsCl3 molecule is nonzero due to the noncancellation of the bond dipole moment in the trigonal pyramidal geometry. The electronegativity of an atom is the strength with which it may attract bound electron pairs to its side. The polarity of AsCl3 is discussed in our previous post.

As a result, the As-Cl bond’s dipole moment is high due to the polarization of the bonds and one lone pair of electrons on Arsenic, and all As-Cl bonds’ dipoles are arranged in the asymmetrical AsCl3 molecular geometry. The AsCl3 molecule has a nonzero net dipole moment.

The electron dot structure of the AsCl3 molecule is also known as the AsCl3 Lewis structure. It determines the number of outermost valence electrons as well as the electrons engaged in the AsCl3 molecule’s bond formation. The outermost valence electrons of the AsCl3 molecule must be understood while considering the Lewis structure of the molecule.

The Arsenic atom is the middle element in AsCl3 molecular geometry, with five electrons in its outermost valence electron shell, whereas the chlorine atom has seven electrons in its outermost valence electron shell. The chlorine atom has seven valence electrons.

The AsCl3 has a total of 26 valence electrons as a result of the foregoing above-said reasoning. With the core central Arsenic atom, the three terminals with three chlorine atoms form covalent bonds, leaving the Arsenic atom with one lone pair in the middle of trigonal pyramidal geometry.

Because lone pairs on the terminal chlorine atoms create interaction with As-Cl bond pairs(but it is negligible in the ground state of the AsCl3 molecule). The bond angle of the Cl-As-Cl bond in the trigonal pyramidal molecular geometry is approximately 100 degrees. This angle is less than the CH4 molecule bond angle. The As-Cl bond length is 207pm(picometer).

To sketch the AsCl3 Lewis structure by following these instructions:

Step-1: AsCl3 Lewis dot Structure by counting valence electrons on the Arsenic atom

To calculate the valence electron of each atom in AsCl3, look for its periodic group from the periodic table. The nitrogen and halogen group families, which are the 15th and 17th groups in the periodic table, are both made up of Arsenic and chlorine atoms respectively. In their outermost shells, chlorine and Arsenic have seven and five valence electrons respectively.

Calculate the total number of valence electrons in the AsCl3 molecule’s outermost valence shell. The first step is to determine how many electrons are in the AsCl3 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 AsCl3 Lewis diagram. The AsCl3 molecule’s core Arsenic atom can be represented as follows:

Total outermost valence shell electron of Arsenic atom in AsCl3= 5
Total outermost valence shell electron of chlorine atom in AsCl3= 7
The AsCl3 molecule has one central Arsenic and three chlorine atoms. Then the total outermost valence shell electrons can be calculated as follows
∴ Total outermost valence shell electrons available for AsCl3 Lewis structure( dot structure) = 5+3*7= 26 valence electrons in AsCl3.
calculation of total valence electron of AsCl3 molecule

Choose the atom with the least electronegative value atom and insert it in the center of the molecular geometry of AsCl3. We’ll choose the least electronegative value atom in the AsCl3 molecule to place in the center of the AsCl3 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.

The first step is to put five valence electrons around the Arsenic atom as given in the figure.

Step-2: Lewis Structure of AsCl3 for counting valence electrons around the terminal chlorine atoms

As a result, Arsenic is the third atom in the periodic table’s nitrogen family group. Chlorine is the second member of the halogen family. The electronegative value of the chlorine atom is higher than that of the Arsenic atom in the AsCl3 molecule. Furthermore, chlorine has a seven electrons limit since Arsenic is the less electronegative element in the AsCl3 molecule.

In the AsCl3 Lewis structure diagram, the Arsenic atom can be the center atom of the molecule. As a result, central Arsenic in the AsCl3 Lewis structure, with all three chlorine atoms arranged in a trigonal pyramidal geometry.

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

Step-3: Lewis dot Structure for AsCl3 generated from step-1 and step-2

Connect the exterior and core central atom of the AsCl3 molecule with three single As-Cl bonds. In this stage, use three chlorine atoms on the outside of the AsCl3 molecule to the central Arsenic atom in the middle.

Count how many electrons from the outermost valence shell have been used in the AsCl3 structure so far. Each As-Cl single bond carries two electrons because each Arsenic atom is connected to three chlorine atoms by three As-Cl single bonds. Bond pairings of As-Cl are what they’re called.

So, out of the total of 26 valence electrons available for the AsCl3 Lewis structure, we used six electrons for the AsCl3 molecule’s three As-Cl single bonds. The AsCl3 molecule has one lone pair of electrons in the central Arsenic atom.

Place the valence electrons in the As-Cl bond pairs starting with the core Arsenic, three chlorine atoms in the AsCl3 molecule. In the AsCl3 Lewis structure diagram, we always begin by introducing valence electrons from the central Arsenic atom(in step1). As a result, wrap around the central Arsenic atom’s bond pair valence electrons first (see figure for step1).

The Arsenic atom in the molecule gets only 8 electrons around its molecular structure. This central Arsenic atom is octet stable. But it has one lone pair. Arsenic is a brownish solid in nature. Arsenic catch fire in the exposure to air. But Arsenic is used in matchboxes and firecrackers.

Chlorine(Cl2) is in the gaseous state at normal temperature and pressure. It is used as a chlorinating agent in the field of organic chemistry. It is a highly corrosive gas. It is responsible for dry corrosion in the metal bodies. It is very reactive to bio-micro organisms. It is also used as a disinfectant in water treatment plants.

Arsenic requires 8 electrons in its outermost valence shell to complete the molecular octet stability, six electrons bond pairs in three As-Cl single bonds, and one lone pair in the central Arsenic atom. Then lone pair of electrons on the chlorine atoms of the AsCl3 molecule is placed in a trigonal pyramidal geometry. Arsenic already shares 8 electrons to the three As-Cl single bonds. Then place the valence electron in the chlorine atoms, it placed around seven electrons on each atom(step-2). 18 valence electrons were placed around three chlorine atoms as lone pairs of electrons.

We’ve positioned 18 electrons around the three-terminal chlorine atoms(step-3), which is represented by a dot, in the AsCl3 molecular structure above. The Arsenic atom completes its molecular octet stability in the AsCl3 molecule because it possesses six electrons in its (three As-Cl single bonds) bond pairs with three chlorine in the outermost valence shell.

Count how many outermost valence shell electrons have been used so far using the AsCl3 Lewis structure. three electron bond pairs are shown as dots in the AsCl3 chemical structure, whereas three single bonds each contain two electrons. The outermost valence shell electrons of the AsCl3 molecule(bond pairs) are six as a result of the calculation. The total valence electron in an Arsenic atom is 8.

So far, we’ve used 26 of the AsCl3 Lewis structure’s total 26 outermost valence shell electrons. One lone pair of electrons on the Arsenic atom in the trigonal pyramidal geometry of the AsCl3 molecule.

Complete the middle Arsenic atom stability and, if necessary, apply a covalent bond. The central Arsenic atom undergoes octet stability(due to three single bond pairs of electrons).

The core atom in the AsCl3 Lewis structure is Arsenic, which is bonded to the three chlorine atoms by single bonds (three As-Cl). With the help of three single bonds, it already shares 8 electrons. As a result, the Arsenic follows the octet rule and has 8 electrons surrounding it on the three terminals of the AsCl3 molecule’s trigonal pyramidal geometry.

How to calculate the formal charge on Arsenic and Chlorine atoms in AsCl3 Lewis Structure?

Calculating formal charge on the Arsenic of AsCl3 molecule:

The formal charge on the AsCl3 molecule’s Arsenic central atom often corresponds to the actual charge on that Arsenic central atom. In the following computation, the formal charge will be calculated on the central Arsenic atom of the AsCl3 Lewis dot structure.

To calculate the formal charge on the central Arsenic atom of the AsCl3 molecule by using the following formula:
The formal charge on the Arsenic atom of AsCl3 molecule= (V. E(P)– L.E(P) – 1/2(B.E))
V.E (P) = Valence electron in a Arsenic atom of AsCl3 molecule
L.E(P) = Lone pairs of an electron in the Arsenic atom of the AsCl3 molecule.
B.E = Bond pair electron in P atom of AsCl3 molecule
calculation of formal charge on Arsenic atom in AsCl3 molecule

The Arsenic core atom (three single bonds connected to three chlorine atoms ) of the AsCl3 molecule has five valence electrons, one lone pair of electrons(two electrons), and six bonding pairing valence electrons. Put these values for the Arsenic atom in the formula above.

Formal charge on Arsenic atom of AsCl3 molecule = (5- 2-(6/2)) =0

In the Lewis structure of AsCl3, the formal charge on the central Arsenic atom is zero.

Calculating formal charge on the chlorine atom of AsCl3 molecule:

The formal charge on the AsCl3 molecule’s chlorine terminal atoms often corresponds to the actual charge on that chlorine terminal atoms. In the following computation, the formal charge will be calculated on the terminal chlorine atom of the AsCl3 Lewis dot structure.

To calculate the formal charge on the terminal chlorine atom of the AsCl3 molecule by using the following formula:
The formal charge on the chlorine atom of AsCl3 molecule= (V. E(Cl)– L.E(Cl) – 1/2(B.E))
V.E (Cl) = Valence electron in a chlorine atom of AsCl3 molecule
L.E(Cl) = Lone pairs of an electron in the chlorine atom of the AsCl3 molecule.
B.E = Bond pair electron in Cl atom of AsCl3 molecule
calculation of formal charge on chlorine atom in AsCl3 molecule

The chlorine terminal atoms of the AsCl3 molecule have seven valence electrons, three lone pairs of electrons(six electrons), and two bonding pairing valence electrons(single bond). Put these values for the chlorine atom in the formula above.

Formal charge on chlorine atom of AsCl3 molecule = (7- 6-(2/2)) =0

In the Lewis structure of AsCl3, the formal charge on the terminal chlorine atom is zero.

Summary:

In this post, we discussed the method to construct the AsCl3 Lewis structure. First, the valence electrons are placed around the Arsenic atom. Second, place the valence electron on the chlorine atoms. Finally, when we combined the first and second steps. It gives AsCl3 Lewis structure. Need to remember that, if you follow the above-said method, you can construct molecular dot structure very easily.