Question

Define and explain the formation of polar and non-polar covalent bonds. State and discuss the cause of their similarities and differences. Use the case of water and hydrocarbons as the basis for your discussion.

Answer 1

Nonpolar covalent bonds are a type of bond that occurs when two atoms share a pair of electrons with each other. These shared electrons glue two or more atoms together to form a molecule. Like children who share toys, atoms involved in a nonpolar covalent bond equally share electrons. An example of a nonpolar covalent bond is the bond between two hydrogen atoms because they equally share the electrons. Another example of a nonpolar covalent bond is the bond between two chlorine atoms because they also equally share the electrons. Nonpolar covalent bonds are very strong bonds requiring a large amount of energy to break the bond.

- Nonpolar covalent bonds are extremely important in biology. They form the oxygen we breathe and help make up our living cells. One kind of nonpolar covalent bond that is very important in biology is called a peptide bond. A peptide bond joins together chains of amino acids, which are involved in the construction of our DNA. Amino acids are comprised of several atoms like carbon, oxygen, nitrogen and hydrogen.

Polar covalent bonding is a type of chemical bond where a pair of electrons is unequally shared between two atoms. In a polar covalent bond, the electrons are not equally shared because one atom spends more time with the electrons than the other atom. In polar covalent bonds, one atom has a stronger pull than the other atom and attracts electrons. Remember how electrons carry a negative charge? Well, when electrons spend more time with one atom, it causes that atom to carry a partial negative charge. The atom that does not spend as much time with the electrons carries a partial positive charge. To remember a polar covalent bond, instead say 'puller covalent,' and remember one atom has more 'pull' on electrons than the other atom.

- Your life actually depends on polar covalent bonding. A water molecule, abbreviated as H2O, is an example of a polar covalent bond. The electrons are unequally shared, with the oxygen atom spending more time with electrons than the hydrogen atoms. Since electrons spend more time with the oxygen atom, it carries a partial negative charge.

- Another example of a polar covalent bond is between a hydrogen and a chlorine atom. In this bond, the chlorine atom spends more time with the electrons than the hydrogen atom. Because of this unequal sharing of electrons, the chlorine atom carries a partial negative charge, and the hydrogen atom carries a partial positive charge.

Cause of their similarities and differences:

- A molecule is classified as a polar molecule when the arrangement of the atoms is such that one end of the molecule has a positive electrical charge and the other end has a negative charge. A polar molecule forms when an atom of high electronegativity bonds with a less electronegative atom. A polar molecule has electrical poles.

- Water is a polar molecule. Ammonia, Sulfur Dioxide, and Hydrogen Sulfide are case in point of polar molecules of materials, which are gases under standard conditions.

- Conversely, a non-polar molecule does not have electrical poles. The electrons are distributed more equally. Therefore, a non-polar molecule does not have a profusion of charges at the opposite ends. The majority of hydrocarbon liquids are non-polar molecules. An example of this is gasoline. Examples of non-polar molecule gases are Helium, Hydrogen, nitrogen, and methane among others. In addition, oil is a non-polar molecule.

- Therefore, a molecule in which the bond dipoles present do not cancel each other out is a polar molecule. A non-polar molecule, in essence, is when the charges all cancel each other out. Non-polar molecules do not have charges at their ends.