Commonly Tested Lewis Structures

We draw Lewis Structures to predict:

-the shape of a molecule.

-the reactivity of a molecule and how it might interact with other molecules.

-the physical properties of a molecule such as boiling point, surface tension, etc.

Drawing the Lewis Structure for PH₃

Video: Drawing the Lewis Structure for PH₃

For the PH3 Lewis structure we first count the valence electrons for the PH3 molecule using the periodic table. Once we know how many valence electrons there are in PH3 we can distribute them around the central atom and attempt to fill the outer shells of each atom.

The PH3 Lewis structure has 8 valence electrons.

Remember that hydrogen (H) only needs two valence electrons to have a full outershell.

The Lewis structure for PH3 is similar the the structure for NH3 since both P and N are in the same group on the Periodic table.

It is helpful if you:

• Try to draw the PH₃ Lewis structure before watching the video.
• Watch the video and see if you missed any steps or information.
• Try structures similar to PH₃ for more practice.

List of Lewis Structures

Acetone	BF3	BH4-	BrF5	BrO3-	C2H2	C2H4	ClO-
CH4	ClO2-	ClO2	ClO4-	CO	CS2	H2O	H3O+
HCl	HNO3	I3-	ICl4-	IF5	N2	N3-	NH2OH
NH3	NO2-	NO2	NO3-	O2	OF2	PCl5	PH3
PO33-	PO43-	SCl2	SF4	SF6	SO3	SO42-	XeF2
XeF4