How can you tell if a molecule is polar or non polar just by looking at

This is actually quite easy if you are familiar already with the position of the elements in the periodic table. Polarity of a molecule is directly linked to the electronegativities of the element which formed the chemical bond. The simplest definition of electronegativity is the tendency or the ability of the element to attract electrons to complete the valence shell, thus we can deduce that the halogens are the most electronegative. The bigger the difference between the electronegativities of the bonding elements, the more polar is the molecule. Thus, the farther away the two elements are, the more polar is the molecule.

electronegativity values of elements can be seen in the internet.

for organic compounds, molecules that are polar contains the -OH, the -COOH, and the amine group. Hope this helps.

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