Lewis Structure of H2Se (With 6 Simple Steps to Draw!)

I’m super excited to teach you the lewis structure of H2Se in just 6 simple steps.

Infact, I’ve also given the step-by-step images for drawing the lewis dot structure of H2Se molecule.

So, if you are ready to go with these 6 simple steps, then let’s dive right into it!

Lewis structure of H2Se contains single bonds between the Selenium (Se) atom and each Hydrogen (H) atom. The Selenium atom (Se) is at the center and it is surrounded by 2 Hydrogen atoms (H). The Selenium atom have 2 lone pairs.

Let’s draw and understand this lewis dot structure step by step.

(Note: Take a pen and paper with you and try to draw this lewis structure along with me. I am sure you will definitely learn how to draw lewis structure of H2Se).

6 Steps to Draw the Lewis Structure of H2Se

Step #1: Calculate the total number of valence electrons

Here, the given molecule is H2Se. In order to draw the lewis structure of H2Se, first of all you have to find the total number of valence electrons present in the H2Se molecule.
(Valence electrons are the number of electrons present in the outermost shell of an atom).

So, let’s calculate this first.

Calculation of valence electrons in H2Se

• For Hydrogen: 

Hydrogen is a group 1 element on the periodic table. ^[1]

Hence, the valence electron present in hydrogen is 1 (see below image).

• For Selenium: 

Selenium is a group 16 element on the periodic table. ^[2]

Hence, the valence electrons present in selenium is 6 (see below image).

Hence in a H2Se molecule, 

Valence electrons given by Selenium (Se) atom = 6
Valence electron given by each Hydrogen (H) atom = 1
So, total number of Valence electrons in H2Se molecule = 1(2) + 6 = 8

Step #2: Select the center atom (H is always outside)

While selecting the center atom, always put the least electronegative atom at the center.

(Remember: Fluorine is the most electronegative element on the periodic table and the electronegativity decreases as we move right to left in the periodic table as well as top to bottom in the periodic table). ^[3]

Here in the H2Se molecule, if we compare the hydrogen atom (H) and selenium atom (Se), then hydrogen is less electronegative than selenium. But as per the rule, we have to keep hydrogen outside.

So, selenium should be placed in the center and the remaining 2 hydrogen atoms will surround it.

Step #3: Put two electrons between the atoms to represent a chemical bond

Now in the above sketch of H2Se molecule, put the two electrons (i.e electron pair) between the selenium atom and each hydrogen atom to represent a chemical bond between them.

These pairs of electrons present between the Selenium (Se) and Hydrogen (H) atoms form a chemical bond, which bonds the selenium and hydrogen atoms with each other in a H2Se molecule.

Step #4: Complete the octet (or duplet) on outside atoms. If the valence electrons are left, then put the valence electrons pair on the central atom

Don’t worry, I’ll explain!

In the Lewis structure of H2Se, the outer atoms are hydrogen atoms.

So now, you have to check whether these hydrogen atoms are forming a duplet or not! (because hydrogen requires only 2 electrons to have a complete outer shell).

You can see in the above image that all the hydrogen atoms form a duplet.

Also, only 4 valence electrons of H2Se molecule are used in the above structure.

But there are total 8 valence electrons in H2Se molecule (as calculated in step #1).

So the number of electrons left to be kept on the central atom = 8 – 4 = 4.

So let’s keep these 4 electrons (i.e 2 electron pairs) on the central atom.

Now, let’s move to the next step.

Step #5: Check whether the central atom has octet or not. If it does not have an octet, then move the electron pair from the outer atom to form a double bond or triple bond

In this step, we have to check whether the central atom (i.e selenium) has an octet or not. 

In simple words, we have to check whether the central Selenium (Se) atom has 8 electrons or not.

As you can see from the above image, the central atom (i.e selenium), has 8 electrons. So it fulfills the octet rule and the selenium atom is stable.

Step #6: Final step – Check the stability of lewis structure by calculating the formal charge on each atom

Now, you have come to the final step and here you have to check the formal charge on selenium atom (Se) as well as each hydrogen atom (H).

For that, you need to remember the formula of formal charge;

Formal charge = Valence electrons – Nonbonding electrons – (Bonding electrons)/2

• For Hydrogen:
  Valence electron = 1 (as it is in group 1)
  Nonbonding electrons = 0
  Bonding electrons = 2
• For Selenium:
  Valence electron = 6 (as it is in group 16)
  Nonbonding electrons = 4
  Bonding electrons = 4

Formal charge	=	Valence electrons	–	Nonbonding electrons	–	(Bonding electrons)/2
Se	=	6	–	4	–	4/2	=	0
H	=	1	–	0	–	2/2	=	0

So you can see above that the formal charges on selenium as well as hydrogen are “zero”.

Hence, there will not be any change in the above structure and the above lewis structure of H2Se is the final stable structure only.

Each electron pair (:) in the lewis dot structure of H2Se represents the single bond ( | ). So the above lewis dot structure of H2Se can also be represented as shown below.

Related lewis structures for your practice:
Lewis Structure of SOCl2
Lewis Structure of ICl2-
Lewis Structure of ICl5
Lewis Structure of C3H6 (Propene)
Lewis Structure of NH2Cl 

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