180°
tetrahederal
linear
trigonal planar
Anything with six electron groups, keep in mind an electron group is a bonded atom or an electron pair, is an octahedral. Anything in an octahedral and a lone pair is the square pyramidal geometry. So all angles between the atoms are a little less than 90 degrees and the angle of the electron pair is greater than 90.
180°
109.5
The electron geometry is tetrahedral when there are 4 electron groups around the central atom. This means the electron groups are arranged in a 3D shape resembling a pyramid with a triangular base.
Electron geometry for this is tetrahedral. There are two O-F single bonds, which makes 2 electron groups. There are two lone pairs around oxygen, which make up the last two electron groups. Molecules with four electron groups has a tetrahedral Electron geometry.
tetrahederal
If there are only three electron groups around an atom, they would be arranged in a trigonal planar geometry. This arrangement minimizes repulsion between the electron groups, placing them 120 degrees apart in a flat plane. The central atom would have a bond angle of approximately 120 degrees between the electron groups. If one of the groups is a lone pair, the geometry would adjust to a trigonal pyramidal shape.
If there are three electron groups around an atom, they will be arranged in a trigonal planar geometry to minimize repulsion between the groups. This arrangement positions the electron groups 120 degrees apart in a flat plane. The central atom will be at the center, with the three groups extending outwards. This geometry is typical for molecules with a steric number of three, such as boron trifluoride (BF₃).
linear
three dimensional arrangement of atoms electron-group geometry
To determine the structural geometry of a molecule, structural pair geometry must be used. These are the amounts of pairs found surrounding a specific molecule, and they are unique to each type of atom.
The electron geometry of NCl3 is trigonal pyramidal (four electron groups around the central nitrogen atom). The molecular geometry of NCl3 is also trigonal pyramidal, as the three chlorine atoms and lone pair of electrons repel each other to form this shape.
trigonal planar