Tetrahedral
Molecules with 4 VSEPR pairs adopt a tetrahedral VSEPR shape.
In molecules with a tetrahedral VSEPR shape, the VSEPR pairs are ideally separated by an angle of 109◦ to achieve maximum separation. Depending on the number of lone pairs present, four different molecular shapes are possible.
AX4, 0 lone pairs, VSEPR shape: tetrahedral, molecular shape: tetrahedral. CH4 is an example of a molecule with the formula AX4. Its molecular structure is called tetrahedral. It has four bond pairs, which adopt an X-A-X angle of 109◦ to achieve maximum separation.
AX3E, 1 lone pair, VSEPR shape: tetrahedral, molecular shape: trigonal pyramidal
AX2E2, 2 lone pairs, VSEPR shape: tetrahedral, molecular shape: bent
AXE3, 3 lone pairs, VSEPR shape: tetrahedral, molecular shape: linear
When connecting 4 atoms to a central atom in a tetrahedral arrangement, their positions do not matter. Convince yourself of this by following these next steps with the tetrahedral molecules of CH2Cl2 and CHCl3.
1. On a separate piece of paper draw the perspective diagram of the molecule with the atoms in all possible positions.
2. Using the appropriate link (CH2Cl2 or CHCl3), rotate the molecule to see if you can make all of the versions of the molecule that you found in step 1.