The key difference between linear and bent molecules is that linear molecules have atoms bonded to each other, forming a straight molecule, whereas bent molecules have atoms arranged in a bend-shape with an angle.
The terms linear molecules and bent molecules describe the shapes of different molecules. We can categorize different chemical compounds into different groups depending on the shape of the molecule; linear, angular/bent, planar, pyramidal, etc. Linear and bent shapes are the simplest among them.
CONTENTS
1. Overview and Key Difference
2. What are Linear Molecules
3. What are Bent Molecules
4. Side by Side Comparison – Linear vs Bent Molecules in Tabular Form
5. Summary
What are Linear Molecules?
Linear molecules are straight molecules having a bond angle of 180 degrees. Basically, these molecules contain a central atom bonded to two other atoms via single, or double bonds (sometimes there can be triple bonds as well). The polarity of this type of molecules is zero if the two bonded atoms are identical. However, if there are two different atoms bonded to a central atom forming a linear molecule, it forms a polar compound. The coordination number of the central atom is two because it has two bonded atoms.
Figure 01: Shape of a Linear Molecule
Moreover, the central atom usually has either no lone electron pairs or three lone electron pairs. Some common examples of linear molecules include carbon dioxide (the central atom is carbon and two oxygen atoms are bonded to the carbon atom via double bonds forming a nonpolar compound), acetylene (contains a triple bonded carbon moiety bonded to two hydrogen atoms via single bonds forming a linear molecule), hydrogen cyanide (contains a central carbon atom bonded to one hydrogen atom via a single bond and to one nitrogen atom via a triple bond), etc.
What are Bent Molecules?
Bent molecules are angular molecules having a bond angle that is below 180 degrees. This means these molecules are nonlinear molecules. Most of the times, some atoms such as oxygen form bent molecules because of their electron configuration. The bond angle of a bent molecule is determined by the electronegativity of each atom in the molecule, which causes the repulsions or attractions between the atoms.
Figure 02: Shape of a Bent Molecule
We can commonly observe a nonlinear arrangement of molecules in triatomic molecules and ions containing only main group elements. The bent structure of these molecules is a result of the presence of lone electron pairs in the central atom. The most common examples of bent molecules include water, nitrogen dioxide, CH2, etc.
What is the Difference Between Linear and Bent Molecules?
The key difference between linear and bent molecules is that linear molecules have atoms bonded to each other, forming a straight molecule, whereas bent molecules have the atoms arranged in a bend-shape with an angle. Moreover, linear molecules are straight molecules having a bond angle of 180 degrees while bent molecules are angular molecules having a bond angle that is below 180 degrees.
The following infographic summarizes the difference between linear and bent molecules.
Summary – Linear vs Bent Molecules
The shape or geometry of different molecules can be used to categorize the molecules into different groups. Linear and bent molecules are two such groups of molecules. The key difference between linear and bent molecules is that linear molecules have the atoms bonded to each other, forming a straight molecule whereas bent molecules have the atoms arranged in a bend-shape with an angle.
Reference:
1. “Bent Molecular Geometry.” Wikipedia.org, 30 May 2020, Available here.
Image Courtesy:
1. “Linear-3D-balls” (Public Domain) via Commons Wikimedia
2. “Bent-3D-balls” (Public Domain) via Commons Wikimedia