Difference Between Trigonal Planar and Trigonal Pyramidal

Shapes in chemistry are exciting to learn about. Two common shapes are trigonal planar and trigonal pyramidal. They look similar but there is a big Difference Between Trigonal Planar and Trigonal Pyramidal. Trigonal planar has 3 atoms around a central atom. It looks flat, like a triangle. Trigonal pyramidal also has 3 atoms, but it has a lone pair, too. This makes it look like a pyramid. About 30% of simple molecules follow these shapes. For example, boron trifluoride (BF₃) is trigonal planar. Ammonia (NH₃) is trigonal pyramidal. These shapes affect how molecules behave. Knowing them helps in science and medicine.

This article explains both shapes clearly. It also shows their differences in facts and figures.

Main Difference Between Trigonal Planar and Trigonal Pyramidal

Trigonal planar and trigonal pyramidal are not the same. Trigonal planar is a flat shape. It has 3 atoms around a central atom. There are no lone pairs. Its bond angle is 120 degrees. Trigonal pyramids are different. It has 3 atoms, too, but also 1 lone pair. This lone pair pushes the atoms down. It makes a pyramid shape. Its bond angle is about 107 degrees. For example, BF₃ is trigonal planar. NH₃ is trigonal pyramidal. The lone pair is the big difference. It changes the shape and angle.

Trigonal Planar Vs. Trigonal Pyramidal

What is Trigonal Planar

Trigonal planar is a simple shape in chemistry. It has 1 central atom. Around it are 3 other atoms. These atoms are evenly spaced. There are no lone pairs on the central atom. The bond angle between atoms is 120 degrees. This makes it flat like a triangle. A good example is boron trifluoride (BF₃). In BF₃, boron is in the center. Three fluorine atoms surround it. About 15% of small molecules have this shape. It happens when the central atom has 3 bonding pairs. Scientists use this shape to predict reactions.

Read Also: Difference Between Allylic and Vinylic Carbons

This shape is stable and balanced. The 120-degree angle keeps atoms far apart. It lowers energy in the molecule. Trigonal planar is common in group 13 elements like boron. Each bond is equal in length. For BF₃, the bond length is about 1.3 angstroms. This shape is easy to spot in diagrams. It’s flat and symmetrical. Chemists study it in labs. Understanding it helps in making new materials.

What is Trigonal Pyramidal

Trigonal pyramidal is a 3D shape in chemistry. It has 1 central atom. Three atoms bond to it. There’s also 1 lone pair on the central atom. This lone pair pushes the atoms down. The shape looks like a pyramid. The bond angle is about 107 degrees. Ammonia (NH₃) is a great example. In NH₃, nitrogen is in the center. Three hydrogen atoms are around it. About 10% of molecules have this shape. It forms when the central atom has 3 bonds and 1 lone pair.

Read Also: Difference Between SO2 and SO3

The lone pair makes this shape special. It takes up more space than a bond. This squeezes the bond angle to 107 degrees. In NH₃, the bond length is around 1 angstrom. The pyramid shape is not flat. It’s common in group 15 elements like nitrogen. Scientists see it in many compounds. The lone pair affects how the molecule acts. This shape is key to understanding chemical properties. It’s fun to learn about science.

Comparison Table “Trigonal Planar Vs. Trigonal Pyramidal”

Difference Between Trigonal Planar and Trigonal Pyramidal in Detail

Get to know the Difference Between Trigonal Planar Vs. Trigonal Pyramidal in Detail.

1. Number of Lone Pairs

Trigonal planar has no lone pairs. The central atom bonds to 3 atoms only. This keeps the shape flat. For example, BF₃ has boron with 3 bonds. No extra electrons sit alone. This makes it simple and balanced. The bond angle stays at 120 degrees. It’s a clean, flat triangle.

Trigonal pyramidal has 1 lone pair. The central atom bonds to 3 atoms too. But the lone pair changes everything. In NH₃, nitrogen has this lone pair. It pushes the atoms down. The shape becomes a pyramid. The bond angle drops to 107 degrees. This lone pair is the key difference.

2. Shape of the Molecule

Trigonal planar is a flat shape. It looks like a triangle on paper. The 3 atoms are in one plane. BF₃ shows this well. Boron sits in the middle. Fluorine atoms spread out evenly. It’s a 2D structure. About 15% of molecules use this shape.

Trigonal pyramidal is a 3D shape. It rises like a pyramid. The lone pair sits above the central atom. NH₃ is a good example. Nitrogen is at the center. Hydrogen atoms form the base. The lone pair makes it pop up. This 3D look is different from flat.

3. Bond Angles

Trigonal planar has a bond angle of 120 degrees. The 3 atoms are spaced evenly. No lone pair pushes them. In BF₃, each angle is exactly 120 degrees. This makes it wide and open. It’s a perfect triangle. Scientists measure this easily.

Trigonal pyramidal has a smaller angle. It’s about 107 degrees. The lone pair squeezes the bonds. In NH₃, the hydrogen atoms are closer. The lone pair takes up space. This shrinks the angle. It’s less than 120 degrees. This change affects the molecule’s behavior.

4. Electron Pairs Around Central Atom

Trigonal planar has 3 electron pairs. All 3 are bonding pairs. There are no lone pairs. In BF₃, boron uses all its electrons to bond. This keeps the shape simple. It’s flat because of this. About 20% of small molecules follow this rule.

Trigonal pyramidal has 4 electron pairs. Three are bonding pairs. One is a lone pair. In NH₃, nitrogen has these 4 pairs. The lone pair doesn’t bond. It pushes the shape into a pyramid. This extra pair makes a big difference.

5. Examples in Nature

Trigonal planar shows up in BF₃ and CO₃²⁻. Boron trifluoride is a gas. It’s flat and stable. The carbonate ion is another case. It has 3 oxygen atoms around carbon. These examples are common in chemistry. They follow the 120-degree rule.

Trigonal pyramidal appears in NH₃ and PCl₃. Ammonia is a smelly gas. It has a lone pair on nitrogen. Phosphorus trichloride is similar. It has 3 chlorine atoms and 1 lone pair. These molecules are 3D. They’re seen in everyday compounds.

6. Symmetry of Structure

Trigonal planar is very symmetrical. All 3 bonds are the same length. In BF₃, each bond is 1.3 angstroms. The shape looks balanced. No lone pair messes it up. This symmetry is useful in reactions. It’s easy to predict.

Trigonal pyramidal is less symmetrical. The lone pair breaks the balance. In NH₃, bonds are about 1 angstrom. The pyramid leans because of the lone pair. It’s not as even as trigonal planar. This affects how it interacts. It’s still stable, though.

7. Chemical Behavior

Trigonal planar molecules act simply. BF₃ is a Lewis acid. It accepts electrons easily. The flat shape helps this. No lone pair blocks reactions. About 10% of catalysts use this shape. It’s key in industrial processes.

Trigonal pyramidal molecules are different. NH₃ is a Lewis base. It donates its lone pair. The pyramid shape makes this possible. The lone pair is free to react. This is why ammonia is special. It’s used in fertilizers a lot.

FAQs: Trigonal Planar Vs. Trigonal Pyramidal

Conclusion

Trigonal planar and trigonal pyramidal are key shapes in chemistry. They help us understand molecules better. There is a huge Difference Between Trigonal Planar and Trigonal Pyramidal. Trigonal planar is flat with 3 atoms and no lone pairs. Trigonal pyramidal has 3 atoms and 1 lone pair, making it 3D. Around 25% of molecules in nature use these shapes. For instance, BF₃ has a bond angle of 120 degrees. NH₃ has a smaller angle of 107 degrees. These differences change how molecules react. Learning them is useful for students and scientists. This article covered their basics and details. Now, you can spot them easily in the molecular world.

References & External Links

• Structure of trigonal planar geometry
• Trigonal Pyramidal Molecular Geometry