SEH2 Lewis Structure: Drawings, Hybridization, Shape, Charges,Pair And Detailed Facts


Electron dot structure gives idea about the basic structure of a molecule. This article will discuss about seh2 lewis structure and the method of drawing it.

Outer shell electrons are shown in the seh2 lewis structure around the involved atoms. These electrons are responsible for chemical properties of the molecule. So from this lewis structure we can predicts the facts about the hybridization, shape and other things of the molecule.

How to draw lewis structure for SEH2

seh2 Lewis structure gives basic idea about shape of the molecule with help of the outer shell electrons. These electrons are responsible for chemical properties in the molecule.

To draw seh2 lewis structure, the atomic symbols of atoms are written, that is ‘Se’ for Selenium and ‘H’ for Hydrogen. The outer orbit electrons of atom are shown by dot symbols around that particular atom of the Hydrogen Selenide molecule.

Selenium is a ‘group 16’ element and Hydrogen is a ‘group 1’ element in the Periodic table.

Electronic configuration of Selenium: [Ar] 3d10 4s2 4p4. Electronic configuration of Hydrogen: 1s1. So outer most orbit electrons of Selenium atom are six and that of Hydrogen atom is one.

Hence the total number of the outer shell electrons are {6 + (1×2)} =8 in the molecule. Hence four pairs of electrons participate to form a SeH2 molecule.

Less electronegative atom becomes the central atom in the molecule. So Hydrogen atom should be the central atom. But it should have minimum two electrons to be a central atom, which is not possible for Hydrogen atom. Selenium atom becomes the central atom of the molecule.

Two electron pairs form sigma bonds (single bond) between the Selenium atom and the two Hydrogen atoms. Remaining four nonbonding electrons concentrate over the central atom Selenium.

Straight lines are used for showing the bonding electrons between the Selenium and Hydrogen atoms in the molecule.

Seh2 lewis structure shape

VSEPR theory (Valence shell electron pair repulsion theory) will help to determine the shape of the Hydrogen Selenide molecule.

If there is a minimum repulsion between the outer shell electrons of atoms in the molecule, the lewis structure will be stable one. This theory states that these electrons are arranged themselves according to this.

This theory assumes that, the nonbonding electron cloud (lone pair) contain more space than the bonding electrons. The repulsion between lone pair- lone pair electron cloud is greater than the repulsion between lone pair- bond pair electron cloud. Bond pair- bond pair repulsion is least among these.

Hence if a central atom contains unshared electron pair, the geometry of the molecule varied from the real one.

Hybridization of atomic orbital of Selenium is sp3 in the molecule. For this the geometry of the SeH2 molecule should be tetrahedral. But central atom has two unshared pair of electron cloud over it.

For repulsion between the two nonbonding electron cloud, they increase the distance between them. This effect in the angle between the bonding electron cloud. These results in a “V”- shape SeH2 molecule.

seh2 lewis structure
shape of seh2 lewis structure

SEH2 lewis structure formal charges

The electron dot structure with no formal charge is regarded as the energetically stable structure of the molecule among all the possible electron dot structure.

Formal charge of a atom in a molecule = (total number of outer shell electrons – nonbonding electrons – (1/2×bonding electrons))

From the Periodic table, we know that outer most orbit electrons of Selenium are six and that of Hydrogen atom is one. In the molecule, Selenium atom has four unshared electrons where Hydrogen has no such electrons.

Formal charge for the central atom Selenium is = {6- 4- (1/2×4)} = 0.

Formal charge for the each Hydrogen atom is = {1- 0- (1/2×2)} = 0.

As the formal charge of the each atom in the molecule is zero, hence the formal charge of the molecule, SeH2 is also Zero.

SEH2 lewis structure lone pairs

In a molecule lone pair contains that type of electrons which don’t take part in the bonding. Lone pair electron cloud is totally under control of the belonging atom.

In seh2 lewis structure, there eight outer shell electrons are present. Among these electrons only four electrons participate in bonding between Selenium and Hydrogen atoms. Remaining all are non-bonding electrons which are called lone pair.

From the orbital hybridization, we know that this lone pair electron cloud belong to the 4s and 4p orbital of the Selenium atom. The shape of the molecule is dependent on these non- bonding electrons.

SEH2 hybridization

In the hybridization, mixing up of atomic orbital involve. This concept is important for describing the shape of the seh2 lewis structure.

The new hybridized orbital is different in energy and shape with respect to the component orbital’s energy. In this Hydrogen Selenide molecule, we only consider the hybridization of the Selenium atom. This helps to determine the shape of the molecule.

In the ground state of Selenium atom, it has two unpaired electrons in 4p orbital. So these can form two sigma bonds in this state. Beside this it has two pairs of electrons in 4s and 4p orbital. These remain as nonbonding electrons of the molecule.

These 4s and 4p orbital mixed up and form new sp3 hybridized orbital. Overlap between the bonding electron cloud will be greater after the hybridization than the ground state orbital overlap.

The new sp3 hybridized orbital of Selenium produces bonding orbital with the 1s atomic orbital of Hydrogen atom.

SEH2 lewis structure resonance

If an atom of a molecule has unshared electron over it, then the electron cloud can be delocalized to the vacant orbital of the next atom. In the way resonance structures are formed.

In the seh2 lewis structure central atom has non-bonding electrons but Hydrogen atom has no vacant orbital to accommodate the electrons as it has only 1s orbital.

Hence no resonance structure can be shown for Hydrogen Selenide molecule.

SEH2 lewis structure octet rule

Octet rule explains the electronic stability of seh2 lewis structure with full filled outer orbit by electrons.

All main group elements of the Periodic table like to have eight electrons in the last shell of electronic configuration. This tend to have full filled electronic shell is named as Octet rule. Only Hydrogen atom can have highest two electrons in the orbit. This is because it has only ‘K’ orbit with 1s orbital.

Selenium has six electrons in the outer orbit as a ‘group 16’ element. It prefers two more electrons to be like nearest Noble gas Krypton. Hydrogen atom has one electron in the outer orbit, so it accepts electron from Selenium atom.

In this way both atoms cover eight electrons in the outer shell. This gives the molecule stable structure. That makes the molecule lower in energy.

SEH2 polar or nonpolar

Polarity is a physical property of a molecule if the molecule has a net dipole moment generated by polar bonds, where bond dipole moment (µ) = separated charge (δ) × distance between charge(r).

In the Hydrogen selenide molecule, electro- negativity of Selenium (Se) is 2.55 and that of Hydrogen atom is 2.2 on the Pauling scale. For this low difference between the electro-negativity of the atoms, an unequal charge separation occurs slightly in the molecule. This results in the formation of a net dipole moment in the molecule.

How strongly an atom can pull the electron cloud of a covalent bond towards it, is the measurement of the electro-negativity of that atom. For the difference between the electro-negativity of the atoms unequal charge separation occurs.

This gives a direction vector of the dipole moment of bonds. If the direction vectors can’t neutralize each other, a net dipole moment is generated in the molecule.

In the Hydrogen Selenide molecule, Selenium atom has six outer most orbit electrons. SeH2 molecule has total eight outer most orbit electrons. Among these four electrons form bond and Selenium has four unshared electrons.

The geometry of the molecule should be tetrahedral. But for the repulsion between nonbonding electron pair of the central atom Selenium, the shape of the molecule becomes ‘V’- liked shape.

seh2 lewis structure
polarity of seh2 lewis structure

For the distorted shape, the direction of dipole moments for electro-negativity can’t neutralize each other. Hydrogen Selenide becomes a polar molecule for the bent structure.

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