POLARITY-OF-MOLECULES science concepts.pptx

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1. POLARITY OF MOLECULES

2. Introduction Molecule is a group of two or more atoms held together by chemical bonds.

3. Polarity of Molecules The bond or the molecular polarities depend upon the electronegativities of the atoms or the molecules. A molecule is basically said to be either a polar molecule, non- polar molecule or ionic molecule. https://youtu.be/nqi6aTopejk?si=sZSL87unb3HWtun4

4. What is a polar molecule? A polar molecule is a molecule in which one end of the molecule is slightly positive, while the other end is slightly negative.

5. Polar Molecules: A polar molecule is usually formed when the one end of the molecule is said to possess more positive charges and whereas the opposite end of the molecule has negative charges, creating an electrical pole. When a molecule is said to have a polar bond, then the centre of the negative charge will be on one side, whereas the centre of positive charge will be in the different side. The entire molecule will be a polar molecule.

6. Examples of polar molecules Water (H2O) is polar, Ammonia (NH3) is polar, Sulfur dioxide (SO2) is polar, Hydrogen sulfide (H2S) is polar.

7. What is a nonpolar molecule? Nonpolar molecules are defined as molecules that do not have any electrical charges or partial charges. Nonpolar molecules are made of atoms that have a similar value of electronegativity. Electronegativity is the tendency of an atom to attract electrons.

8. Non- Polar Molecules: A molecule which does not have the charges present at the end due to the reason that electrons are finely distributed and those which symmetrically cancel out each other are the non- polar molecules. In a solution, a polar molecule cannot be mixed with the non-polar molecule. For example, consider water and oil. In this solution, water is a polar molecule whereas oil behaves as a non-polar molecule. These two molecules do not form a solution as they cannot be mixed up.

9. Examples of non-polar molecule Oxygen (O2), and nitrogen (N2). Other nonpolar molecules include carbon dioxide (CO2) and the organic molecules methane (CH4), toluene, and gasoline.

10. Why water and oil do not mixed together? Liquid water is held together by hydrogen bonds. (Liquid water has fewer hydrogen bonds than ice.) Oils and fats not have any polar part and so for them to dissolve in water they would have to break some of water s hydrogen bonds. Water will not do this so the oil is forced to stay separate from the water.

11. How to determine if a molecule is a polar molecule or non-polar molecule? To determine if a molecule is polar or non-polar, you need to consider the molecular structure and the electronegativity difference between its atoms. Here are the steps to follow: 1. Identify the molecule’s atoms and their electronegativity values. You can find electronegativity values in a periodic table.

12. 2. Determine the molecular geometry of the molecule. This can be done by drawing the Lewis structure and predicting the geometry based on VSEPR (Valence Shell Electron Pair Repulsion) theory.

3. Calculate the electronegativity difference between the atoms in the molecule. This difference is crucial in determining the polarity of the molecule.

13. 4. If the molecule has a linear or symmetric shape (e.g., CO2, BeF2) and the electronegativity difference is low (usually less than 0.5), it is considered non-polar. This is because the dipoles created by the electronegativity difference cancel each other out due to the symmetry.

5. If the molecule has a non-linear geometry (e.g., H2O, NH3, CH4) and the electronegativity difference between the atoms is significant (usually greater than 0.5), it is considered polar. In these cases, the dipoles do not cancel each other out, resulting in a net molecular dipole moment.

14. 6. If the molecule is made up of non-polar atoms only (e.g., He, Ne, O2), it is considered non-polar, even without calculating the electronegativity difference.

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