VSEPR naming system for molecules with a steric number above 9

Since most of the chemistry resources I've come across don't go above 9 for VSEPR* molecules, I came up with a VSEPR naming system for molecules with a steric number above 9 here it is:


Step 1: Determine if the steric number is odd or even

EVEN

Step 2 (even) If it is even , subtract 2

Step 3 (even) then divide the number you got by 2

this is the number of points of the 2 base shapes of the antiprism

Step 4 (even) You then use the Greek prefix or the common name of the shape ( Greek prefix example : Hexagonal, common name example : square )

Step 5 (even) you can then either name it using the gyroelongated method or the antiprismatic method.

Step 6 (even) (Gyroelongated**) The gyroelongated method involves adding the word gyroelongated in front of the name of the base shape and add bipyramid at the end.

Step 6 (even) ( Antiprismatic )the antiprismatic method involves inserting the word antiprismatic after the base name and adding bipyramid at the end.

ODD

Step 2 (odd) If it Odd then you subtract 1

Step 3 (odd) Then you divide by 2
this is the number of points of the 2 base shapes of the antiprism

Step 4 (odd) You then use the Greek prefix or the common name of the shape

Step 5 (odd) you can then either name it using the gyroelongated method or the Capped method.


Step 6 (odd) ( Gyroelongated) In This naming method you put the word Gyroelongated in front of the base name and then add Pyramid at the end


Step 6 (odd) ( Capped) In this naming system you but the word capped in front of the base name and add antiprism to the end.

Example

Lets start easy and take the lowest steric number in this naming system: 10.

Step 1 it is even

Step 2 so subtract 2 = 8


Step 3 and divide by 2 = 4                                                                                    

Step 4 the common name for a shape with 4 points is a square


Step 5 lets use the Gyroelongated method


Step 6 Name: Gyroelongated Square Bipyramid ( which can be shortened to Gyroelongated Octahedron because an Octahedron is a square bipyramid.)

Gyroelgonated Octahedron shape

VSEPR model of a molecule with the steric number 10. 

Explanation of name and what the words mean:

Gyroelongated means to make the shape longer by inserting an antiprism*. An anti-prism is a prism with the base shapes not in line and twisted relative to each other and they being connected by triangles. A Square is a shape with four points ant equal sides, and a Bipyramid is a shape with a point on the top and bottom , with a pyramid on the top and bottom.

lets go with a harder one , 31.

Step 1 it is odd

Step 2 so subtract 1 = 30


Step 3 and divide by 2 =15                                                                                    

Step 4 the Greek prefix- name for a shape with 15 points is a Pentakaidecagonal


Step 5 lets use the Capped method

VSEPR model of a molecule with the steric number 31

Step 6 Capped Pentakaidecagonal Anitprism

the Capped part means there is a point or cap on the top of the shape

 Capped Pentakaidecagonal Anitprism ( Capped method ) or Gyroelongated Pentakaidecagonal Pyramid ( Gyroelongated method ) shape.

Now let us do the steric number 100.
.
Step 1 it is even


Step 2 so subtract 2 = 98


Step 3 and divide by 2 = 49                                                                                    

Step 4 the Greek prefix- name for a shape with 49 points is called a Tetracontakaienneagon

Step 5 lets use the Antiprismatic method

Step 6 Name: Tetracontakaienneagonal Antiprismatic Bipyramid


Finally lets do 499

Step 1 it is odd

Step 2 so subtract 1 = 498


Step 3 and divide by 2 =249                                                                                    

Step 4 the Greek prefix- name for a shape with 249 points is a Dihectokaitetracontakaienneagonal


Step 5 lets use the Gyroelongated method


Step 6 Gyroelongated Dihectokaitetracontakaienneagonal Pyramid


*VSEPR theory is based on the theory that electron pairs repel each other and want to be far away as possible in 3 dimensional space. It is a system for determining molecular geometry

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**"This is called "gyroelongation", which means that an antiprism is joined to the base of a solid, or between the bases of more than one solid." Wikipedia