Is CO2 polar or nonpolar? What is the parameter to decide the polarity of molecules? First, we take an example for better understanding let us have two molecules HCl (heteroatomic) and H2 (homoatomic). Hydrogen is highly electropositive and fluorine is a highly electronegative atom in the periodic table. In HF, the fluorine has a tendency to attract the shared pair electron and gets a partial negative charge and hydrogen gets a partial positive charge due to the electronegativity difference between hydrogen and chlorine.
On the other hand, there is no electronegativity difference between H-H so, we conclude that HF is polar and H2 is a nonpolar molecule. Here, is very important to understand the term dipole moment. Dipole moment tells us which covalent compound is polar or which is nonpolar.
Dipole Moment
Dipole moment tells us the percentage of ionic character in a covalent compound. Dipole moment is a vector quantity, a symbol used for dipole moment is u (meo). For example, HCl is a polar molecule due to the electronegativity difference between hydrogen and chlorine. Chlorine is electronegative, attracts the electrons, and gets a partial negative charge and hydrogen gets a partial positive charge. The formula of dipole moment is u=q×d. where Q is equal to charge on anyone atom and d is equal to intramolecular distance.
As we discussed above, the dipole moment is a vector quantity so its direction is from less electronegative atom to more electronegative atom. If any atom has lone pair then the direction of dipole moment is from atom to lone pair.
How we judge the molecule is polar or nonpolar?
How can we determine which molecule is Polar or nonpolar? To find the polarity of molecules we determine the net dipole moment of molecules. There are two possibilities:
- If unet is zero then the molecule is nonpolar.
- If unet is not zero then the molecule is polar.
Is CO2 Polar or Nonpolar?
CO2 is formed from two atoms i.e. carbon and oxygen via a covalent bond. Carbon is electropositive but oxygen is an electronegative atom. Oxygen has the tendency to attract the shared pair of electrons. Due to the electronegativity difference between oxygen and carbon, oxygen gets a partial negative charge and carbon gets a partial positive charge.
As we know that the direction of dipole moment is from less electronegative to a more electronegative atom. In the case of carbon dioxide, the dipole moment is from carbon to oxygen but the value of the net dipole moment is zero. So, carbon dioxide is a nonpolar molecule. In CO2, the individual dipole moment exists. That’s why we discuss above that if we want to judge the molecule polar or nonpolar, we determine the net dipole moment. The individual dipole moment is also called the bond moment.
Is carbon dioxide has a bond moment? yes
Is carbon dioxide has a dipole moment? No
Parameter to Decide the Polarity of Molecules: Electronegativity
The electronegativity difference is not only the parameter to judge the polarity of molecules. The molecule can be nonpolar despite the difference in electronegativity if the net dipole moment is zero. Electronegativity is the tendency of an atom to attract the shared pair of electrons in a covalent bond.
Difference between Electronegativity and Electron affinity
| Electron Affinity | Electronegativity |
|---|---|
| Electron affinity is the tendency to accept electrons. | Electronegativity is the tendency to attract electrons. |
| For example, chlorine has the highest electron affinity in the periodic table. | Fluorine has the highest electronegativity in the periodic table. |
| Chlorine attracts the electrons but is not as powerful as fluorine but chlorine also accepts the electrons due to its large size. | Fluorine has a better tendency to attract electrons but does not accept electrons due to its small size. |
What are Polar and Nonpolar molecules?
Polar Molecules
When a covalent bond is formed they share electrons equally with each other. A polar bond is a bond in which there are two poles in an opposite direction positive and negative pole. Why these poles are formed? The only reason behind pole formation is the significant electronegative difference between bonding atoms. Due to this electronic cloud displaces near to more electronegative atoms.
As it is clear from the image the electronic cloud is closer to the more electronegative B atom.
Examples of polar bonded molecules
Some examples of polar bonded molecules are given such as HF, HCl, HBr, HI, water, and methanol. These are some famous examples of polar molecules.
Nonpolar Molecules
A covalent bond is known as the non-polar if both the bonded atoms are of the same electronegativity. There is no pole formation when the electronegativity difference is close to zero. Non-polar bonds share electrons equally between bonded atoms.
As it is clear from the image that both electrons A and B attract electrons equally.
Examples of non-polar bonded molecules
Some common examples of nonpolar molecules are H2, Cl2, BeCl2, CO2, C2H2, BF3, and CCl4 are some examples of nonpolar molecules.
Physical Properties of CO2
- Carbon dioxide is odorless, colorless, and tasteless.
- CO2 is soluble in water and it increases with the increase of pressure.
- CO2 is about 1.5 times heavier than air.
- It turns wet blue Litmus Paper into the red.
- It converts to white solid at -78 degrees centigrade, called dry ice.
- CO2 is neither combustible nor a supporter of combustion.
Uses of CO2
- Carbon dioxide is used in the preparation of drinks such as soda water, beer, and so on.
- When carbon dioxide is cooled at about -78 degrees centigrade it turns into ice (dry ice). Dry ice is used for refrigeration and preservation of food.
- In its natural form photosynthesis has made life possible since animals depend on plants.
- Carbon dioxide is used in fire extinguishers. There are two chemicals in a fire extinguishers that in contact produce carbon dioxide.
- This gas is heavier than air and makes it easier to extinguish the fire.
