Noncovalent Bonds - Online Tutor, Practice Problems & Exam Prep

Non-covalent bonds are interactions between atoms that arise from full or partial charges, differing from covalent bonds, which involve electron sharing. Key types include ionic bonds and hydrogen bonds, both classified as relatively strong electrostatic interactions. While weak Van der Waals interactions exist, they are less emphasized in biological contexts. Understanding these bonds is crucial for grasping molecular interactions in biological systems, influencing processes like enzyme activity and cellular signaling.

Noncovalent Bonds

So now that we've discussed the covalent bonds in our previous lesson videos, in this video we're going to begin our lesson on non-covalent bonds. Non-covalent bonds can be defined as interactions between 2 atoms resulting from full or partial charges. Now, unlike covalent bonds that we talked about in our previous lesson videos, there is absolutely no sharing of electrons in non-covalent bonds. Recall from our previous lesson videos that the term covalent means sharing of electrons, but if we add the root non in front of that, then that means no sharing of electrons. That's an important distinction between covalent and non-covalent bonds.

There are actually several different types of non-covalent bonds that are commonly found in biology. These different types of non-covalent bonds are broken up into two groups: there are relatively strong electrostatic interactions and then there are the relatively weak Van Der Waals interactions. Moving forward in our course, we're not going to talk much about these weak Van Der Waals interactions. This is something that you would learn more about in a chemistry course, but for our biology course, we're going to be focusing mainly on these relatively strong electrostatic interactions. There are two types of these relatively strong electrostatic interactions that we're going to talk more about moving forward: the ionic bonds and the hydrogen bonds.

If we take a look at our map down below this table, you'll see that the table corresponds to this map of our lesson from down below. Notice here we have our map of the lesson on chemical bonds and we know that we've been following this map by following the leftmost branches first. We've already discussed covalent bonds in our previous lesson videos including non-polar covalent bonds and polar covalent bonds. Moving forward, we're going to focus more of our attention on the non-covalent bonds, specifically on these relatively strong electrostatic interactions, and that's why we have this strong character here in this electrocution symbol. Those are going to include the ionic bonds and the hydrogen bonds and again we'll get to talk more about each of those types of bonds moving forward in our course.

The weak Van Der Waals interactions that you see over here with this weak guy here who can't lift these weights, this is something that we're not going to discuss much moving forward in our course. Again, you'll get to learn more about these weak Van der Waals interactions in your chemistry course. But this here concludes our brief introduction to non-covalent bonds and once again we'll get to learn more about them as we move forward. So I'll see you all in our next video.

Which of the following are considered to be very weak non-covalent chemical bonds?

• A. Polar covalent bonds.
• B. Ionic bonds
• C. Non-polar covalent bonds.
• D. Van der Waals bonds.
• E. Hydrogen bonds.
• F. Electrostatic bonds.

Here’s what students ask on this topic:

What are non-covalent bonds and how do they differ from covalent bonds?

Non-covalent bonds are interactions between atoms that arise from full or partial charges, without the sharing of electrons. In contrast, covalent bonds involve the sharing of electrons between atoms. The term 'covalent' means sharing of electrons, while 'non-covalent' means no sharing of electrons. Non-covalent bonds include ionic bonds and hydrogen bonds, which are relatively strong electrostatic interactions, and Van der Waals interactions, which are weaker. These bonds are crucial in biological systems for processes like enzyme activity and cellular communication.

What are the main types of non-covalent bonds found in biological systems?

The main types of non-covalent bonds found in biological systems are ionic bonds and hydrogen bonds. Ionic bonds occur between atoms with full charges, while hydrogen bonds occur between a hydrogen atom covalently bonded to an electronegative atom (like oxygen or nitrogen) and another electronegative atom. These bonds are relatively strong electrostatic interactions. Additionally, there are weaker Van der Waals interactions, which are less emphasized in biological contexts but still play a role in molecular interactions.

Why are non-covalent bonds important in biological systems?

Non-covalent bonds are crucial in biological systems because they influence molecular interactions that are essential for various biological processes. For example, they play a key role in enzyme activity, where the binding of substrates to enzymes often involves non-covalent interactions. They also facilitate cellular communication by enabling the binding of signaling molecules to their receptors. These interactions are generally reversible, allowing for dynamic processes within cells.

How do ionic bonds and hydrogen bonds differ in terms of their formation and strength?

Ionic bonds form between atoms with full opposite charges, resulting from the transfer of electrons from one atom to another. These bonds are relatively strong due to the electrostatic attraction between the charged ions. Hydrogen bonds, on the other hand, form when a hydrogen atom covalently bonded to an electronegative atom (such as oxygen or nitrogen) interacts with another electronegative atom. While hydrogen bonds are also strong electrostatic interactions, they are generally weaker than ionic bonds. Both types of bonds are essential for the structure and function of biological molecules.

What role do Van der Waals interactions play in biological systems?

Van der Waals interactions are weak, non-covalent interactions that occur due to transient dipoles in molecules. While they are less emphasized in biological contexts compared to ionic and hydrogen bonds, they still play a significant role in stabilizing the three-dimensional structures of proteins and other macromolecules. These interactions help in the proper folding of proteins and the formation of lipid bilayers in cell membranes. Despite their weakness, the cumulative effect of many Van der Waals interactions can significantly influence molecular stability and function.