Chemistry Homework

Question

Which element in the polar covalent bond would be δ^–? 

1. C
2. B
3. H
4. Cl

Answer 1

Hello! To answer this question specifically you need a little more information, because you would need to know what two atoms the covalent bond is between (there are just 4 atoms listed here separately, and it isn't indicated what atom they are each bonding to in the covalent bond you are describing).

Here are is how to determine the polarity of a covalent bond:

Background info: Look at a periodic table, with the trends of electronegativity in mind (it helps to look at a periodic table on google that also lists the arrows showing electronegativity trends). Electronegativity of atoms increases from left to right, and increases from bottom to top. The noble gasses (He, Ne, etc) are excluded from this (they are already fully "happy" with the number of valence electrons they have), so the MOST electronegative element in the periodic table is F, Fluorine.

How to find covalent bond polarity: Find both elements on the periodic table and determine which one is more electronegative based on the electronegativity trends discussed above.

-For example, if the covalent bond we are talking about is between C and O, we know O is more electronegative that C, because it is farther to the right (and closer to F, which we know is the most electronegative element). Therefore, the partial negative charge, δ^–, will be on the side of the bond closer to O (because O is more electronegative than C, it pulls electrons towards it more strongly, and gets that partial negative charge near it because the two atoms are not sharing the electrons perfectly equally).

*This rule can be applied to all covalent bonds, and all covalent bonds will be at least a little polar UNLESS they are between two of the same element. For example, C bonded to C will have a non-polar covalent bond, because carbon has the exact same electronegativity as another carbon atom. The electrons here are shared perfectly equally, and there is no polarity in this covalent bond. This bond is called a non-polar covalent bond.

Hope this helps! Feel free to reach out if you need more chemistry help and would like to schedule an online tutoring session!