Why is CH 4 nonpolar whereas CH 3 Cl is polar?
CH4 is symmetrical; CH3Cl is not. Look up the 3D shape of each. CH4 is tetrahedral in shape so each of the polarities of each of the C-H bonds cancel each other. With CH3Cl; however, You have 3 C-H bond at tetrahedral angles but the C-Cl bond, more polar than the C-H bond, occupies the fourth apex of the tetrahedron and the CH3Cl is not canceled out as in CH4 so CH3Cl is polar.
The polarity of a molecule is determined by the electronegativity difference between the atoms in the molecule and the molecular geometry. In the case of CH4 (methane), which consists of a carbon atom bonded to four hydrogen atoms, the molecule is nonpolar. This is because carbon and hydrogen have similar electronegativities, resulting in a very small electronegativity difference. Additionally, the molecular geometry of CH4 is tetrahedral, with the four hydrogen atoms bonded symmetrically around the carbon atom, creating a symmetrical distribution of charge. As a result, the molecule has no net dipole moment and is therefore nonpolar.
In contrast, CH3Cl (chloromethane) is a polar molecule. The chlorine atom is more electronegative than carbon and hydrogen, causing it to draw the bonded electron pairs towards itself, creating a partial negative charge on the chlorine atom and partial positive charges on the carbon and hydrogen atoms. The molecular geometry of CH3Cl is tetrahedral as well, but the presence of the more electronegative chlorine atom causes an asymmetrical distribution of charge. This results in an overall dipole moment, making CH3Cl a polar molecule.
To understand why CH4 is nonpolar while CH3Cl is polar, we need to consider the molecular geometry and the electronegativity difference between the atoms in each molecule.
First, let's analyze the molecular geometry of each molecule. In CH4 (methane), the carbon atom is bonded to four hydrogen atoms, forming a tetrahedral shape. Each hydrogen atom is evenly distributed around the carbon atom, resulting in a symmetrical arrangement. This symmetry ensures that the polar bonds cancel each other out, making CH4 a nonpolar molecule.
On the other hand, in CH3Cl (chloromethane), one of the hydrogen atoms is replaced by a chlorine atom. The carbon-chlorine bond is polar because chlorine is more electronegative than carbon. The chlorine atom draws electron density towards itself, creating a partial negative charge on the chlorine atom and leaving a partial positive charge on the carbon atom. Additionally, the three hydrogen atoms form a trigonal pyramidal shape around the carbon atom.
Since the molecule is not symmetrical due to the presence of the chlorine atom, the partial positive charge on the carbon and the partial negative charge on the chlorine do not cancel each other out. As a result, CH3Cl is a polar molecule.
In summary, the difference in electronegativity between the carbon and chlorine atoms in CH3Cl causes the molecule to be polar, while the symmetrical distribution of the hydrogen atoms around the carbon atom in CH4 makes it a nonpolar molecule.