How to Determine Polarity

[Madilyn Schindler 3E]

How do we determine whether a bond is polar or not when we aren't given the actual electronegativity values (and therefore can't find the difference in electronegativity to tell whether it's polar or not)?

[Selena Quispe 2I]

A bond is polar if there is an unequal share of electrons, causing a dipole moment. Just look at which element is more electronegative and you can infer that one end will have a partial positive charge and the other end will have partial negative charge! Attached below is an example! I hope this helps and good luck studying!!

[Zach Jaffery 1K]

You can use a periodic table during the test, and if you remember the electronegativity trends across the periodic table (top right is most electronegative, bottom left is least) you can usually figure it out with pretty good accuracy. If the bond is a cation plus an anion, then its ionic. If it's made of two of the same atoms then it's non-polar. If it's two different atoms bonding, then it's usually polar. If it's two different atoms bonding and the electronegativities are close enough to be confusing (ie hydrogen sulfide), I'm sure we'd be provided with the actual electronegativity values. Hopefully this answered the question!

[Madilyn Schindler 3E]

Thank you so much!

[Alan Nguyen 2I]

When we look at the definition of a polar covalent bond, it is due to the unequal sharing of electrons between the two atoms. Just remember that this occurs due to two atoms with different electronegativities; you can find whether the electronegativities are different by looking at their positions on the periodic table. F is the most electronegative element, and as you move further away from it the elements become more electronegative. Hope this helps!

[Jonathan Shyu 3L]

Polarity can be determined in two ways: first way is to see what a molecule is composed of, and second way is to view the bonds/electron sharing of the molecule. If a molecule is composed of the same element and share electrons evenly, then it is nonpolar, while if a molecule is made up of different elements that share electrons unevenly, then it is polar. On the other hand, if a molecule is made of different atoms but electrons are shared evenly, then it is polar.

[Desiree Eshraghi 3A]

You do not need exact values just some basic comparison memorization (like how O and N have higher electronegativity than H and C). Furthermore, another tip when looking at polar molecules in general is to check for asymmetry as that tends to reveal whether the molecule is polar (and therefor has polar bonds).

[Trisha Badjatia 2L]

If you aren't given the exact electronegative values, you can use the trends on the periodic table: the top-right-most elements have the highest electronegativity, with F being the highest. So you just compare the locations of elements on the periodic table.

[Joseph Liao 3C]

Electronegativity generally increases as you move up and to the right on the periodic table. Thus, if you have a periodic table, you can make a pretty good guess about which atoms in a molecule are more/less electronegative than the other.

[Arad_Badiee_2B]

I just wanted to add an example along with what everyone else said. So when you think about H2O, you consider the Hydrogen-Oxygen bonds. With regards to electronegativity, there is a significant enough difference in the two, and the Hydrogen will have a partial positive charge while the Oxygen will have a partial negative charge in the sharing of electrons. Therefore, the bonds are polar.

[Madelyn_Rios_2c]

If you aren't given the exact values of electronegativity, you can tell which element is more electronegative by looking at its position on the periodic table. The top-right is the most electronegative and the bottom-left is the least.