AsF3 Molecular Geometry - Science Education and Tutorials

Q: What is the molecular notation for AsF3 molecule?

AsF3 molecular notation is AX3N1.

Arsenic trifluoride(AsF3) has the composition of one Arsenic and three Fluorine atoms. What is the molecular geometry of Arsenic trifluoride?. Drawing and predicting the AsF3 molecular geometry is very easy by following the given method. Here in this post, we described step by step to construct AsF3 molecular geometry. Arsenic and Fluorine come from the 15th and 17th family groups in the periodic table. Arsenic and Fluorine have five and seven valence electrons respectively.

Table of Contents

Key Points To Consider When drawing The AsF3 Molecular Geometry

A three-step approach for drawing the AsF3 molecular can be used. The first step is to sketch the molecular geometry of the AsF3 molecule, to calculate the lone pairs of the electron in the central Arsenic atom; the second step is to calculate the AsF3 hybridization, and the third step is to give perfect notation for the AsF3 molecular geometry.

The AsF3 molecular geometry is a diagram that illustrates the number of valence electrons and bond electron pairs in the AsF3 molecule in a specific geometric manner. The geometry of the AsF3 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 AsF3 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 As-F single bonds (dipole moment properties of the AsF3 molecular geometry). Two Arsenic-Fluorine single bonds in the Arsenic trifluoride(AsF3), for example, are polarised toward the more electronegative value Fluorine atoms, and because all three (As-F) single bonds have the same size and polarity, their sum is nonzero due to the AsF3 molecule’s bond dipole moment due to pulling the electron cloud to the three side of trigonal pyramidal geometry, and the AsF3 molecule is classified as a polar molecule.

The molecule of Arsenic trifluoride(with trigonal pyramidal shape AsF3 molecular geometry) is tilted at 100 degrees bond angle of F-As-F. It has a difference in electronegativity values between Arsenic and Fluorine atoms, with Fluorine’s pull the electron cloud being greater than Arsenic’s. But bond polarity of As-F 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 AsF3 molecule has a nonzero dipole moment due to an unequal charge distribution of negative and positive charges in the trigonal pyramidal geometry.

Overview: AsF3 electron and molecular geometry

According to the VSEPR theory, the AsF3 molecule ion possesses trigonal pyramidal molecular geometry. Because the center atom, Arsenic, has three As-F single bonds with the three Fluorine atoms surrounding it. The F-As-F bond angle is 100 degrees in the trigonal pyramidal AsF3 molecular geometry. The AsF3 molecule has a trigonal pyramidal geometry shape because it contains three Fluorine atoms in the geometry and four corners with one lone pair of electrons.

There are three As-F single bonds at the AsF3 molecular geometry. After linking the three Fluorine atoms and one lone pair of electrons on the Arsenic atom in the trigonal pyramidal form, it maintains the pyramidal-shaped structure. In the AsF3 molecular geometry, the As-F single bonds have stayed in the three terminals and one lone pair of electrons on the Arsenic atom of the trigonal pyramidal AsF3 molecule.

The center Arsenic atom of AsF3 has one lone pair of electrons, resulting in trigonal pyramidal AsF3 electron geometry. However, the molecular geometry of AsF3 looks trigonal pyramidal and has one lone pair of electrons on the Arsenic of the AsF3 geometry. It’s the AsF3 molecule’s symmetrical geometry. As a result, the AsF3 molecule is polar.

How to find AsF3 hybridization and molecular geometry

Calculating lone pairs of electrons on Arsenic in the AsF3 geometry:

1. Determine the number of lone pairs of electrons in the core Arsenic atom of the AsF3 Lewis structure. Because the lone pairs of electrons on the Arsenic atom are mostly responsible for the AsF3 molecule geometry planar, we need to calculate out how many there are on the central Arsenic atom of the AsFl3 Lewis structure.

Use the formula below to find the lone pair on the Arsenic atom of the AsF3 molecule.
L.P(P) = V.E(P) – N.A(As-F)/2

Lone pair on the central Arsenic atom in AsF3 = L.P(As)
The core central Arsenic atom’s valence electron in AsF3 = V.E(As)
Number of As-Fbonds = N.A (As-F)
calculation for Arsenic atom lone pair in AsF3 molecule.

For instance of AsF3, the central atom, Arsenic, has five electrons in its outermost valence shell, three As-F 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 Arsenic atom of the AsF3 molecule is one.

Calculating lone pair of electrons on Fluorine in the AsF3 geometry:

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

Use the formula below to find the lone pair on the Fluorine atom of the AsF3 molecule.
L.P(F) = V.E(F) – N.A(As-F)

Lone pair on the terminal Fluorine atom in AsF3= L.P(F)
Terminal Fluorine atom’s valence electron in AsF3= V.E(F)
Number of As-F bonds = N.A ( As-F)
calculation for Fluorine atom lone pair in AsF3 molecule.

For instance of AsF3, its terminal atoms, Fluorine, have seven electrons in its outermost valence shell, one As-F single bond connection. This gives a total of three As-F single bond connections. But we are considering only one connection for the calculation.

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

The lone pair of electrons in the Fluorine atom of the AsF3 molecule is six. Three Fluorine atoms are connected with the central Arsenic atom.

In the AsF3 electron geometry structure, the lone pair on the central Arsenic atom is one, lone pairs of electrons in the Fluorine atom have six. Three Fluorine atoms have 18 lone pairs of electrons.

It means there are one lone pair of electrons in the core Arsenic atom. One lone pair of electrons on the central Arsenic atom is responsible for the trigonal pyramidal nature of AsF3 molecular geometry. But in the structure Fluorine atoms are polarised sidewise in their trigonal pyramidal geometry.

The one lone pair of electrons are placed at the top of the AsF3 geometry. Because the Arsenic atom is a lower electronegative value as compared with other atoms in the AsF3 molecule. Three Fluorine atoms are polarized towards the sidewise in the AsF3 structure.

But in reality, the AsF3 has one lone pair of electrons in its structure. This makes the AsF3 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 Fluorine lone pairs and bond pairs. But it is negligible in the ground state.

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

Calculate the number of molecular hybridizations of the AsF3 molecule

What is AsF3 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

AsF3 molecule is made of one Arsenic, three Fluorine atoms. The Fluorine and Arsenic atoms have s and p orbitals. Fluorine comes as the first element from the halogen family in the periodic table. The Arsenic atom also belongs to the nitrogen family group. But it falls as the third element in the periodic table.

When these atoms combine to form the AsF3 molecule, its atomic orbitals are mixed and form unique molecular orbitals due to hybridization.

How do you find the AsF3 molecule’s hybridization? We must now determine the molecular hybridization number of AsF3.

The formula of AsF3 molecular hybridization is as follows:
No. Hyb of AsF3= N.A(As-F bonds) + L.P(P)
No. Hy of AsF3 = the number of hybridizations of AsF3
Number of As-Fbonds = N.A (As-Fbonds)
Lone pair on the central Arsenic atom = L.P(As)
Calculation for hybridization number for AsF3 molecule

In the AsF3 molecule, Arsenic is a core central atom with three Fluorine atoms connected to it. It has one lone pair of electrons on Arsenic. The number of AsF3 hybridizations (No. Hyb of AsF3) can then be estimated using the formula below.

No. Hyb of AsF3= 3+1=4

The AsF3 molecule ion hybridization is four. The Arsenic and Fluorine atoms have s and p orbitals. The sp3 hybridization of the AsF3 molecule is formed when one s orbital and three p orbitals join together to form the AsF3 molecular orbital.

Molecular Geometry Notation for AsF3 Molecule :

Determine the form of AsF3 molecular geometry using VSEPR theory. The AXN technique is commonly used when the VSEPR theory is used to calculate the shape of the AsF3 molecule.

The AXN notation of AsF3 molecule is as follows:
The central Arsenic atom in the AsF3 molecule is denoted by the letter A.
The bound pairs (three As-F bonds) of electrons to the core Arsenic atom are represented by X.
The lone pairs of electrons on the central Arsenic atom are denoted by the letter N.
Notation for AsF3 molecular geometry

We know that Arsenic is the core atom, with two electron pairs bound (three As-F) and one lone pair of electrons. The general molecular geometry formula for AsF3 is AX3N1.

According to the VSEPR theory, if the AsF3 molecule ion has an AX3N1 generic formula, the molecular geometry and electron geometry will both be trigonal pyramidal forms.

Name of Molecule	Arsenic trifluoride
Chemical molecular formula	AsF3
Molecular geometry of AsF3	Trigonal pyramidal
Electron geometry of AsF3	Trigonal pyramidal
Hybridization of AsF3	sp3
Bond angle (F-As-F)	100º degree
Total Valence electron for AsF3	26
The formal charge of AsF3 on Arsenic	0

Summary:

In this post, we discussed the method to construct AsF3 molecular geometry, the method to find the lone pairs of electrons in the central Arsenic atom, AsF3 hybridization, and AsF3 molecular notation. Need to remember that, if you follow the above-said method, you can construct the AsF3 molecular structure very easily.