H2Se Molecular Geometry - Science Education and Tutorials

Q: What is the molecular notation for H2Se molecule?

H2Se molecular notation is AX2N2.

Hydrogen selenide(H2Se) has the composition of one selenium and two hydrogen atoms. What is the molecular geometry of hydrogen selenide?. Drawing and predicting the H2Se molecular geometry is very easy by following the given method. Here in this post, we described step by step to construct H2Se molecular geometry. Selenium and hydrogen come from the 16th and 1st family groups in the periodic table. Selenium and hydrogen have six and one valence electrons respectively.

Table of Contents

Key Points To Consider When drawing The H2Se Molecular Geometry

A three-step approach for drawing the H2Se molecular can be used. The first step is to sketch the molecular geometry of the H2Se molecule, to calculate the lone pairs of the electron in the central selenium atom; the second step is to calculate the H2Se hybridization, and the third step is to give perfect notation for the H2Se molecular geometry.

The H2Se molecular geometry is a diagram that illustrates the number of valence electrons and bond electron pairs in the H2Se molecule in a specific geometric manner. The geometry of the H2Se 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 H2Se 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 two Se-H single bonds (dipole moment properties of the H2Se molecular geometry). Two selenium-hydrogen single bonds in the hydrogen selenide(H2Se), for example, are polarised toward the more electronegative value selenium atoms, and because all two (Se-H) single bonds have the same size and polarity, their sum is nonzero due to the H2Se molecule’s bond dipole moment due to pulling the electron cloud to the two side of tetrahedral geometry, and the H2Se molecule is classified as a polar molecule.

The molecule of hydrogen selenide (with tetrahedral shape H2Se molecular geometry) is tilted at 92 degrees bond angle of H-Se-H. It has a difference in electronegativity values between selenium and hydrogen atoms, with selenium’s pull the electron cloud being greater than hydrogen’s. But bond polarity of Se-H is not canceled to each other in the tetrahedral geometry. As a result, it has a nonzero permanent dipole moment in its molecular structure. The H2Se molecule has a nonzero dipole moment due to an unequal charge distribution of negative and positive charges in the tetrahedral geometry.

Overview: H2Se electron and molecular geometry

According to the VSEPR theory, the H2Se molecule ion possesses tetrahedral molecular geometry. Because the center atom, selenium, has two Se-H single bonds with the two hydrogen atoms surrounding it. The H-Se-H bond angle is 92.1 degrees in the tetrahedral H2Se molecular geometry. The H2Se molecule has a tetrahedral geometry shape because it contains two hydrogen atoms in the tetrahedral and two corners with two lone pairs of electrons.

There are two Se-H single bonds at the H2Se molecular geometry. After linking the two hydrogen atoms and two lone pairs of electrons on the selenium atom in the tetrahedral form, it maintains the tetrahedral-shaped structure. In the H2Se molecular geometry, the Se-H single bonds have stayed in the two terminals and two lone pairs of electrons on the selenium atom of the tetrahedral molecule.

The center selenium atom of H2Se has two lone pairs of electrons, resulting in tetrahedral H2Se electron geometry. However, the molecular geometry of H2Se looks tetrahedral or v-shaped and has two lone pairs of electrons on the selenium of the H2Se geometry. It’s the H2Se molecule’s slight asymmetrical geometry. As a result, the H2Se molecule is slightly polar.

How to find H2Se hybridization and molecular geometry

Calculating lone pairs of electrons on selenium in the H2Se geometry:

Determine the number of lone pairs of electrons in the core selenium atom of the H2Se Lewis structure. Because the lone pairs of electrons on the selenium atom are mostly responsible for the H2Se molecule geometry planar, we need to calculate out how many there are on the central selenium atom of the H2Se Lewis structure.

Use the formula below to find the lone pair on the selenium atom of the H2Se molecule.
L.P(Se) = V.E(Se) – N.A(Se-H)/2

Lone pair on the central selenium atom in H2Se = L.P(Se)
The core central selenium atom’s valence electron in H2Se = V.E(Se)
Number of Se-H bonds = N.A (Se-H)
calculation for selenium atom lone pair in H2Se molecule.

For instance of H2Se, the central atom, selenium, has six electrons in its outermost valence shell, two Se-H single bond connections. This gives a total of two connections.

As a result of this, L.P(Se) = (6 –2)/2=2

The lone pair of electrons in the selenium atom of the H2Se molecule is two.

Calculating lone pair of electrons on hydrogen in the H2Se geometry:

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

Use the formula below to find the lone pair on the hydrogen atom of the H2Se molecule.
L.P(H) = V.E(H) – N.A(Se-H)

Lone pair on the terminal hydrogen atom in H2Se = L.P(H)
Terminal hydrogen atom’s valence electron in H2Se = V.E(H)
Number of Se-H bonds = N.A ( Se-H)
calculation for hydrogen atom lone pair in H2Se molecule.

For instance of H2Se, their terminal atoms, hydrogen, have one electron in its outermost valence shell, one Se-H single bond connection. This gives a total of two Se-H single bond connections. But we are considering only one connection for the calculation.

As a result of this, L.P(H) = (1 –1)=0

The lone pair of electrons in the hydrogen atom of the H2Se molecule is zero. Two hydrogen atoms are connected with the central selenium atom.

In the H2Se electron geometry structure, the lone pairs on the central selenium atom are two, lone pairs of electrons in the hydrogen atom have zero. Two hydrogen atoms have no lone pairs of electrons.

It means there are two lone pairs of electrons in the core selenium atom. Two lone pair of electrons on the central selenium atom is responsible for the tetrahedral nature of H2Se molecular geometry. But in the structure hydrogen atoms are polarised sidewise in their tetrahedral geometry.

The two lone pairs of electrons are placed at another side of the H2Se geometry. Because the hydrogen atom is a lower electronegative value as compared with other atoms in the H2Se molecule. Two hydrogen atoms are polarized towards the sidewise in the H2Se structure.

But in reality, the H2Se has two lone pairs of electrons in its structure. This makes the H2Se 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 hydrogen empty hole and lone pairs of electrons of selenium of another H2Se molecule. Here, the hydrogen of one molecule acts as an acceptor and the selenium of another molecule as a donor. This is called hydrogen bonding between the two H2Se molecules. This is one of the main intermolecular forces in H2Se.

But in the central, selenium atom has two lone pairs of electrons and these lone pair electrons just oppose each other with selenium- hydrogen bond pairs.

Calculate the number of molecular hybridizations of the H2Se molecule

What is H2Se 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

H2Se molecule is made of one selenium, two hydrogen atoms. The hydrogen and selenium atoms have s and p orbitals. But hydrogen atom has only s orbital in the ground state. Hydrogen comes as the first element in the periodic table. The selenium atom also belongs to the oxygen family group. But it falls as the third element in the periodic table.

When these atoms combine to form the H2Se molecule, its atomic orbitals are mixed and form unique molecular orbitals due to hybridization.

How do you find the H2Se molecule’s hybridization? We must now determine the molecular hybridization number of H2Se.

The formula of H2Se molecular hybridization is as follows:
No. Hyb of H2Se= N.A(Se-H bonds) + L.P(Se)
No. Hy of H2Se = the number of hybridizations of H2Se
Number of Se-H bonds = N.A (Se-H bonds)
Lone pair on the central selenium atom = L.P(Se)
Calculation for hybridization number for H2Se molecule

In the H2Se molecule, selenium is a core central atom with two hydrogen atoms connected to it. It has two lone pairs of electrons on selenium. The number of H2Se hybridizations (No. Hyb of H2Se) can then be estimated using the formula below.

No. Hyb of H2Se= 2+2=4

The H2Se molecule ion hybridization is four. The selenium and hydrogen atoms have s and p orbitals. The sp3 hybridization of the H2Se molecule is formed when one s orbital and three p orbitals join together to form the H2Se molecular orbital.

Molecular Geometry Notation for H2Se Molecule :

Determine the form of H2Se molecular geometry using VSEPR theory. The AXN technique is commonly used when the VSEPR theory is used to calculate the shape of the H2Se molecule.

The AXN notation of H2Se molecule is as follows:
The central selenium atom in the H2Se molecule is denoted by the letter A.
The bound pairs (two Se-H bonds) of electrons to the core selenium atom are represented by X.
The lone pairs of electrons on the central selenium atom are denoted by the letter N.
Notation for H2Se molecular geometry

We know that H2Se is the core atom, with two electron pairs bound (two Se-H) and two lone pairs of electrons. The general molecular geometry formula for H2Se is AX2N2.

According to the VSEPR theory, if the H2Se molecule ion has an AX2N2 generic formula, the molecular geometry and electron geometry will both be tetrahedral or V-bent-shaped forms.

Name of Molecule	Hydrogen selenide
Chemical molecular formula	H2Se
Molecular geometry of H2Se	Tetrahedral
Electron geometry of H2Se	Tetrahedral
Hybridization of H2Se	sp3
Bond angle (H-Se-H)	92.1º degree
Total Valence electron for H2Se	8
The formal charge of H2Se on selenium	0

Summary:

In this post, we discussed the method to construct H2Se molecular geometry, the method to find the lone pairs of electrons in the central selenium atom, H2Se hybridization, and H2Se molecular notation. Need to remember that, if you follow the above-said method, you can construct the H2Se molecular structure very easily.