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If the difference in electronegativity for the atoms in a bond is greater than 0.4, the bond is considered. If the difference in electronegativity is less than 0.4, the bond is essentially nonpolar. Sometimes you can tell from drawing out the molecule and looking at the charges and if its evenly spread out.
Polar molecules have an unequal sharing of electrons. For example, in the molecule H2O, O is more electronegative than H, making it attract more electrons. This gives them a partial negative charge, and hydrogen (H) a partial positive charge. The e- sharing is unequal, and therefore the molecule is polar. Non-polar molecules are usually symmetric in terms of sharing electrons.
A polar covalent bond occurs when electrons are shared unequally, so if the difference in electronegativity is greater than or equal to 0.5, the bond is polar. A nonpolar covalent bond occurs when the atoms bonded together are of relatively similar electronegativies.
Whether a bond is polar covalent or nonpolar covalent or iconic can be determined by the difference in electronegativity between the atoms. Typically less than 0.5 is nonpolar, between 0.5 and 2 is polar covalent, greater than 2 is ionic. The electronegativity value of elements can be found easily by searching it, usually the value follows its electron affinity. If you are trying to determine the polarity of a molecule, then the overall shape of that molecule also needs to be considered which I'm sure Dr. Lavelle will get into in future weeks.
to see if a bond is polar or nonpolar can be determined by the difference in electronegativity between the atoms. Determining if the dipoles cancel out, if they do then it is nonpolar and if they dont then it is polar
To determine polarity, you need to look at the electro-negativities of the atoms in the molecule. Electronegativity tends to increase from left to right across the periodic table, and from bottom to top of the periodic table. Two atoms with a fairly substantial difference in electronegativity such as oxygen and hydrogen (i.e. in a water molecule) yields polarity.
I think to tell the difference between nonpolar and polar (there is a charge) you look at the relative electronegativity between the atoms, for example since C and H are close together on the periodic table they have similar electronegativities so a CH4 molecule would be nonpolar because there is not a significant charge.
DMaya_3C wrote:Does electronegativity have any connection with a molecule being polar or nonpolar?
Yes it does! That's what cause polar bonds, the electronegativity difference cause there to be uneven sharing of electrons.
For the most part, different biological elements have a large enough electronegativity to be polar. A notable exception is that a C-H bond is nonpolar. When there are larger molecules with more than just two elements, it becomes much more tricky and requires you to see if the molecule is "balanced". This occurs when there is an equal attraction to electrons in all directions. There can also be molecules that are amphipathic which are both polar and nonpolar such as fatty acids from biology.
Polarity in molecules is based on the difference in electronegativity between bonded atoms. Typically, polar molecules will have polar bonds where the two atoms have vastly different electronegativities, so the electron isn't shared equally. However, nonpolar molecules can also have polar bonds, but tend to be symmetrical which cancels out the difference in polarity.
The difference in electronegativity between bonded atoms determines polarity. As the difference in electronegativity increases, the more polarized the distribution of electrons becomes. A way you can tell polarity is looking at the molecule; if for example a molecule has polar bonds but is symmetrical and the dipoles cancel, the molecule is non polar.
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