Lewis structure of PH3

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The Lewis structure of PH₃ contains three single bonds, with phosphorus in the center, and three hydrogens on either side. There is one lone pair on the phosphorus atom, and the hydrogen atom does not have any lone pair.

Steps

By using the following steps, you can easily draw the Lewis structure of PH₃:

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Calculate formal charge and check stability (if octet is already completed on central atom)

Let’s one by one discuss each step in detail.

#1 Draw skeleton

In this step, first calculate the total number of valence electrons. And then, decide the central atom.

• Let’s calculate the total number of valence electrons

We know that… phosphorus is a group 15 element and hydrogen is a group 1 element. Hence, phosphorus has five valence electrons and hydrogen has one valence electron.

Now PH₃ has one phosphorus atom and three hydrogen atoms.

So the total number of valence electrons = valence electrons of phosphorus atom + (valence electrons of hydrogen atom × 3)

Therefore, the total number of valence electrons = 5 + 3 = 8

• Now decide the central atom

We can not assume hydrogen as the central atom, because the central atom is bonded with at least two other atoms. And hydrogen has only one electron in its last shell, so it can not make more than one bond.

Hence, assume that phosphorus is the central atom.

So now, put phosphorus in the center and hydrogens on either side. And draw the rough skeleton structure for the Lewis structure of PH₃ something like this:

Also read: How to draw Lewis structure of XeF₂ (4 steps)

#2 Show chemical bond

Place two electrons between the atoms to show a chemical bond. Since phosphorus is surrounded by three hydrogens, use six electrons to show three chemical bonds as follows:

Also read: How to draw Lewis structure of N₂O (5 steps)

#3 Mark lone pairs

As calculated earlier, we have a total of 8 valence electrons. And in the above structure, we have already used six valence electrons. Hence, two valence electrons are remaining.

And two valence electrons represent one lone pair.

Note that phosphorus is a period 3 element, so it can keep more than 8 electrons in its last shell. And hydrogen is a period 1 element, so it can not keep more than 2 electrons in its last shell.

Also, make sure that you start marking these lone pairs on outside atoms first. And then, on the central atom.

The outside atoms are hydrogens. But hydrogen can not keep more than 2 electrons in its last shell. Hence, don’t mark the lone pairs on hydrogen.

So the central atom (phosphorus) will get one lone pair.

Now draw the Lewis structure of PH₃ something like this:

In the above structure, you can see that the octet is completed on the central atom (phosphorus), and also on the outside atoms. Therefore, the octet rule is satisfied.

After completing the octet, one last thing we need to do is, calculate the formal charge and check the stability of the above structure.

Also read: How to draw Lewis structure of I₃^– (4 steps)

#4 Calculate formal charge and check stability

The following formula is used to calculate the formal charges on atoms:

Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons

Collect the data from the above structure and then, write it down below as follows:

• For phosphorus atom

Valence electrons = 5
Nonbonding electrons = 2
Bonding electrons = 6

Formal charge = 5 – 2 – ½ (6) = 0

• For each hydrogen atom

Valence electrons = 1
Nonbonding electrons = 0
Bonding electrons = 2

Formal charge = 1 – 0 – ½ (2) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of PH₃ looks something like this:

In the above structure, you can see that the formal charges of both (phosphorus and hydrogen) are zero. Therefore, this is the stable Lewis structure of PH₃.

And each horizontal line drawn in the above structure represents a pair of bonding valence electrons.

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Related

• Lewis structure of XeF₂
• Lewis structure of N₂O
• Lewis structure of I₃^–
• Lewis structure of BCl₃
• Lewis structure of CN^–

External links

• Lewis Structure for PH3 – The University of Maryland
• PH3 (Phosphine) Lewis Structure, Shape, Molecular Geometry – Chemistry School
• PH3 lewis structure, molecular geometry, bond angle, hybridization – Topblogtenz
• PH3 Lewis Structure in 6 Steps (With Images) – Pediabay
• PH3 Lewis Structure, Molecular Geometry, Hybridization, Bond Angle and Shape – Geometry of Molecules
• Draw the Lewis structure for PH3. How many bonds and nonbonding pairs are around the central atom, and what is the shape of this molecule? – Homework.Study.com
• PH3 Lewis Structure, Molecular Geometry, and Hybridization – Techiescientist
• How can I draw the Lewis structure for PH3? – Socratic
• How to draw PH3 Lewis Structure? – Science Education and Tutorials
• Chemical Bonding: PH3 Lewis Structure – The Geoexchange
• Draw the Lewis structure of PH3 – Brainly
• Draw the Lewis structure for the PH3 molecule – Bartleby
• write the lewis structure for PH3 – Numerade
• How many equivalent Lewis structures are necessary to describe the bonding in PH3? – Answers
• What is the total number of valence electrons in the Lewis structure PH3? – OneClass