The electron domain geometry chart is a useful tool for determining the steric number and electron geometry of molecules. It is based on the idea that the central atom in a molecule is surrounded by electron domains, which are groups of electrons that are held together by the bonds between atoms.

To use the electron domain geometry chart, you need to start by drawing the Lewis structure (electron dot structure) for the molecule. This will help you identify the number of lone pairs and the number of atoms attached to the central atom. Then, you can refer to the chart below to determine the steric number and electron geometry.

Here is an example of how to use the electron domain geometry chart:

Let's say we want to find the steric number and electron geometry of PH5. First, we draw the Lewis structure for PH5:

P - H - H - H - H

This shows that the central atom P has 5 atoms attached to it, with no lone pairs. According to the chart below, this means that the steric number is 3 and the electron geometry is trigonal pyramidal.

PH5: Steric Number = 3, Electron Geometry = Trigonal Pyramidal

Similarly, let's find the steric number and electron geometry of BrF3:

Br - F - F - F

This shows that the central atom Br has 3 atoms attached to it, with no lone pairs. According to the chart below, this means that the steric number is 3 and the electron geometry is trigonal planar.

BrF3: Steric Number = 3, Electron Geometry = Trigonal Planar

And let's find the steric number and electron geometry of SH2:

S - H - H

This shows that the central atom S has 2 atoms attached to it, with no lone pairs. According to the chart below, this means that the steric number is 2 and the electron geometry is linear.

SH2: Steric Number = 2, Electron Geometry = Linear

It's worth noting that the difference between electron geometry (steric number) and molecular shape (molecular geometry) lies in how we treat the electron's lone pairs versus the bonds. In electron geometry, we treat both lone pairs and bonds as a single group, whereas in molecular shape, we treat them as separate entities.

In conclusion, the electron domain geometry chart is a useful tool for determining the steric number and electron geometry of molecules. By following the steps outlined above and using the chart below, you can quickly determine the steric number and electron geometry of any molecule.

Electron Domain Geometry Chart:

| Steric Number | Electron Geometry |

| --- | --- |

| 2 | Linear |

| 3 | Trigonal Planar |

| 3 | Trigonal Pyramidal |

| 4 | Tetrahedral |

| 5 | Trigonal Bipyramidal |

Electron domain geometry chart