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

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

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

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

Lewis structure of HCP contains a single bond between a Carbon (C) & Hydrogen (H) atom and a triple bond between the Carbon (C) and Phosphorus (P) atom. The Carbon atom (C) is at the center and it is surrounded by Hydrogen (H) and Phosphorus atom (P). The Phosphorus atom has 1 lone pair.

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 HCP).

6 Steps to Draw the Lewis Structure of HCP

Step #1: Calculate the total number of valence electrons

Here, the given molecule is HCP. In order to draw the lewis structure of HCP, first of all you have to find the total number of valence electrons present in the HCP 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 HCP

• For Hydrogen: 

Hydrogen is a group 1 element on the periodic table.

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

• For Carbon:

Carbon is a group 14 element on the periodic table.

Hence, the valence electrons present in carbon is 4 (see below image).

• For Phosphorus: 

Phosphorus is a group 15 element on the periodic table.

Hence, the valence electrons present in phosphorus is 5 (see below image).

Hence in a HCP molecule, 

Valence electron given by Hydrogen (H) atom = 1
Valence electrons given by Carbon (C) atom = 4
Valence electrons given by Phosphors (P) atom = 5
So, total number of Valence electrons in HCP molecule = 1 + 4 + 5 = 10

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

While selecting the 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). ^[1]

Here in the HCP molecule, hydrogen (H) will always remain outside as per the rule. Now, if we compare the carbon atom (C) and phosphorus atom (P), then carbon is less electronegative than phosphorus.

So, carbon should be placed in the center and the phosphorus atom will surround it.

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

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

These pairs of electrons present between the Hydrogen (H), Carbon (C) and Phosphorus (P) atoms form a chemical bond, which bonds the hydrogen, carbon and phosphorus atoms with each other in a HCP 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 HCP, the outer atoms are hydrogen atom and phosphorus atom.

Hydrogen already has a duplet (see below image).

So now, you have to complete the octet on phosphorus atom (because phosphorus requires 8 electrons to have a complete outer shell).

Now, you can see in the above image that the phosphorus atom forms an octet.

Also, all the 10 valence electrons of HCP molecule (as calculated in step #1) are used in the above structure. So there are no remaining electron pairs.

Hence there is no change in the above sketch of HCP.

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 carbon) has an octet or not.

In simple words, we have to check whether the central Carbon (C) atom is having 8 electrons or not.

As you can see from the above image, the central atom (i.e carbon) has only 4 electrons. So it does not fulfill the octet rule.

Now, in order to fulfill the octet of carbon atom, we have to move the electron pair from the outer atom (i.e phosphorus atom) to form a double bond.

Still, the octet of carbon atom is not fulfilled as it has only 6 electrons.

So again moving another electron pair from the phosphorus atom, we will get the following structure.

Now you can see from the above image that the central atom (i.e carbon), is having 8 electrons. So it fulfills the octet rule and the carbon 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 hydrogen atom, carbon atom as well as phosphorus atom.

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 Carbon:
  Valence electrons = 4 (as it is in group 14)
  Nonbonding electrons = 0
  Bonding electrons = 8
• For Phosphorus:
  Valence electron = 5 (as it is in group 15)
  Nonbonding electrons = 2
  Bonding electrons = 6

Formal charge	=	Valence electrons	–	Nonbonding electrons	–	(Bonding electrons)/2
H	=	1	–	0	–	2/2	=	0
C	=	4	–	0	–	8/2	=	0
P	=	5	–	2	–	6/2	=	0

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

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

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

Related lewis structures for your practice:
Lewis Structure of TeF6
Lewis Structure of SeF5-
Lewis Structure of C2H3F
Lewis Structure of NH2F
Lewis Structure of SeI2 

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