Polar vs Non-Polar Molecules: What you Need to Know

shutterstock_170107070When students take their first biology or chemistry cl9ass, among the first things that they will learn about hare atoms and molecules. The characteristics of atoms and how they bond make up the basic foundations of life. However, many students struggle to understand the atomic elements and the differences between the various types of bonds. They often require additional tutoring and instruction to fully grasp the concept, especially polar vs. non-polar molecules. To prepare for a chemistry test, such as the Regents Chemistry exam, you will probably want to take a Regents Chemistry review course to ensure you understand the basics and everything else you need to know.

The Basics of Atoms and Molecules

Atoms are the building blocks of all matter. Everything, both living and non-living, organic and non-organic, is made up of atoms from one of the elements found on the periodic table. Atoms come together to create molecules, and molecules group together to create matter in a variety of shapes and sizes. Molecules also can be combined to create solutions.

Atoms consist of protons, electrons and neutrons. There are different types of bonds that bring these molecules together. The electrons play an important role in creating the bonds between atoms to form molecules. An atom can have a charge, depending on the balance between the protons, which have a positive charge, and the electrons, which have a negative charge. Understanding the periodic table and the atomic properties of the different elements can enhance your ability to work with the molecules and solutions. You can take Udemy’s Chemistry 101: Part 2 Chemistry of the Elements to learn more about the periodic table.

The Different Types of Bonds

There are a few different types of bonds that bring atoms together to create molecules: ionic, covalent, hydrogen and metallic. The main two types of bonds to learn are ionic and covalent, and they are the strongest types of bonds. Ionic bonds occur when the charges of the electrons attract one another to form a neutral molecule. Ionic bonds are most commonly found in salts, and they form a very powerful bond, although it can be broken by water. Covalent bonds occur when atoms share electrons. Atoms have an outer shell consisting of a certain number of electrons. Atoms like to have that outer shell filled, so they will borrow or share electrons with other atoms. When they share an electron, it creates a very strong bond. There can be single or double covalent bonds. Covalent bonds can create polar or non-polar molecules.

Although most beginner courses focus on ionic and covalent bonds, it is also important to understand hydrogen and metallic bonds. Hydrogen bonds occur when the partial charges that occur during covalent bonds attract one another and bond through a common hydrogen atom. Metallic bonds occur when electrons are shared among all the atoms. This type of bond does not have as significant of a role in biological systems. These bonds are part of the basic fundamentals of chemistry, which you can learn more about by signing up at Udemy.

Polar Bonds

Polar bonds happen when two atoms form a molecule using a covalent bond. When the two atoms share electrons, there is also a change of electron density. If the electrons are not shared equally, then there will be a partial ionic charge. This happens most often in atoms with a large difference in their electronegativity. This charge creates a polarity in the molecule, with one side being more positively charged and the other side more negatively charged. The greater the difference in these charges, the more ionic the bond will be. Polar bonds create a dipole-dipole intermolecular force. A dipole is the separation of the positive and negative electric charge. This force can create a type of bond between polar molecules as well, such as a hydrogen bond. This type of bond is not as strong as some of the other type of bonds and can be easily broken.

Water is the more common polar covalent bond. There is a large difference between the electronegativity in hydrogen and oxygen. The electrons from hydrogen are given to oxygen. Because oxygen already has higher electronegativity than hydrogen, there will be a slight negative charge in the oxygen side and a slight positive charge on the hydrogen side. Other examples of polar molecules include ammonia, ethanol, sulfur dioxide, and hydrogen sulfide.

Non-Polar Molecules

Non-polar molecules occur when the electron sharing during a covalent bond is equal, so there is no ionic charge and the electrons are distributed symmetrically. This will occur among atoms that have similar electronegativity. The charges balance one another, so there is no abundance of charges. Many gases are non-polar molecules, such as hydrogen, helium, oxygen, carbon dioxide and nitrogen. Hydrocarbon liquids such as gasoline, helium, neon, and krypton are likewise non-polar.

What’s the Difference?

The difference between polar and non-polar molecules is the final charge caused by the covalent bond. Polar molecules will have an excess charge due to the imbalance of the electronegativity of the atoms forming the bond that creates a difference of charge in the poles of the molecule. Non-polar molecules will be neutral, due to a balance of electronegativity of the atoms. There is a spectrum of polarity, with many molecules falling within the extremes of polar and non-polar.

Why Polar and Non Polar Matters

Whether a molecule is polar or non-polar can make a difference in several ways. Polar molecules tend to have a slight draw to one another, creating another, albeit less strong bond. They will interact through hydrogen bonds and dipole-dipole intermolecular forces. The charges attract the other molecules, and also will attract other polar molecules of different substances. Alternatively, non-polar molecules do not have these charges, and so they do not have a similar attraction or bonds with one another.

One reason that polarity matters in chemistry is that polar and non-polar molecules do not mix to form a solution. That is why oil and water do not mix: oil is non polar, while water is polar. Another reason that chemists are concerned about polarity is that it influences several physical properties of matter, such as solubility, surface tension, and melting and boiling points.

Learn More About Chemistry Today 

There are many reasons to begin learning more about chemistry – not just because it’s required for a degree or certification. Simple, everyday activities such as cooking can be enhanced by a basic understanding of molecular bonding. For example, when you mix different ingredients together, you can understand better why some mix well while others do not, because it depends on the molecular structure of the substance, as well as the role of emulsifiers in food. Additionally, the boiling point of certain foods changes depending on what other ingredients are added to the mixture. There are many other everyday activities that rely upon chemical interactions, which is why it is important to know chemistry. 

Chemistry is one of the basic sciences students are required to learn in school, but it can be very confusing for many students. Likewise, a basic understanding of atoms, molecules, and bonding is essential to understand many other sciences, including biology. When you take an introduction to biology course, such as one of those offered on Udemy, it is likely to include at least one section on the fundamentals of chemistry. Although it can be confusing at first to master the fundamentals of chemistry, it can help you better understand many other subjects. Atoms coming together to form molecules create everything, since matter is made up of atoms. Understanding the basics of molecules and how they interact with each other can actually have important real-world applications.