Both trigonal planar and trigonal pyramidal are terms used in geometries to describe the three-dimension arrangement of atoms of a molecule in space.
Other types of geometries such as linear, bent, tetrahedral, and octahedral are quite easy to differentiate when compared to the two above.
So, what is the main difference between trigonal planar and trigonal pyramidal? The former has no lone pair electrons in the central atom whereas the latter has one lone pair at the central atom.
The lesson provides detailed insight into the difference between trigonal planar and trigonal pyramidal. Let’s find out more:
You May Also Like: Difference between Independent and Dependent Variables
Comparison Table (Trigonal Planar vs Trigonal Pyramidal)
|Basic Terms||Trigonal Planar||Trigonal Pyramidal|
|Meaning||Has no lone pair electrons in the central atom||Has lone pair electrons in the central atom|
|Plane||Atoms in one plane||Atoms not in one plane|
|Bond Repulsion||Has only bond-bond repulsion||Has both bond- bond and bond- lone pair repulsion.|
|Examples||Boron trifluoride.||Ammonia, Chlorate Ion, and Sulfite Ion|
What Is Trigonal Pyramidal?
It is a geometry shown by molecules having four atoms or ligands. The central atom appears at the apex and the rest appear of the atoms or ligands on the base.
The arrangement of the central atom and the other atoms or ligands results in the formation of a triangle. The central atom tends to have one lone pair of electrons.
Visualization of trigonal pyramidal as tetrahedral geometry makes it easier for understanding.
The lone pair-bond repulsion in trigonal pyramidal is greater than bond-bond repulsion. This makes the bonded three atoms and lone pairs stay apart.
The typical angle between the atoms is about 107 degrees which less than that of tetrahedron geometry.
Examples of molecules showing trigonal planar are ammonia, chlorate ion, and sulfite ion among many others.
What Is Trigonal Planar?
It is a type of geometry portrayed by molecules with four atoms. The geometry shows three atoms on the periphery which are connected to the one at the center to form corners of a triangle.
The central atom determines the geometry in which there is a bond- bond repulsion from the groups of atoms. The atoms appear in one plane and this is the reason behind the name planar.
The angle between the periphery atoms is 120 degrees and these molecules have the same number of atoms. An example of an ideal molecule with trigonal planar is Boron trifluoride.
Examples of inorganic anions that show trigonal planar are carbonates and sulfates. Other complex compounds that normally surround central atoms are three NH2 groups and tend to be bind on the central atom.
Differences Between Trigonal Planar and Trigonal Pyramidal
- The central atom is trigonal planar has no lone pair electrons while trigonal pyramidal has one pair.
- The bond angle between the atoms of trigonal planar is 120 degrees while that of the trigonal pyramidal is 107 degrees.
- The atoms in trigonal planar appear in one plane while trigonal pyramidal does not appear in one place.
- Examples of molecules that show trigonal planar is Boron trifluoride while trigonal pyramidal is ammonia, chlorate ion, and sulfite ion.
- Trigonal planar has bond-bond repulsion. Trigonal pyramidal has both bond-bond and bond-lone pair repulsion.
- Trigonal planar has one plane molecule shape. Trigonal pyramidal molecules lack one plane shape.
- Trigonal pyramidal has three bonded atoms. Trigonal planar has numerous bonded atoms.
You May Also Like:
- Difference between Area and Perimeter
- Difference between 2D and 3D Shapes
- Difference between Area and Volume
Geometry is a wide topic and tends to be complicated. There are a lot of terms used throughout the topic where trigonal planar and trigonal pyramidal are some of them.
Understanding the core difference between trigonal planar and trigonal pyramidal will help you comprehend geometry in an easier way.
More Sources and References
- Trigonal Planar Molecular Geometry. Wikipedia
- Trigonal Pyramidal Molecular Geometry. Wikipedia