I can solve whether the bond is polar or non-polar by looking atthe electronegat

Question

I can solve whether the bond is polar or non-polar by looking atthe electronegativity table:

For example, PH3, or CS2,

But there is a problem for these two molecules, is that

P = 2.1
H = 2.1,

and

C = 2.5
S = 2.5

I know they have a difference of 0, but are they non-polar orpolar?
Polar = 0.3-1.5
Non-Polar = 0.3 below

There is a question that had this type of problem, but it said thatPH3, are still polar covalent bond, and between thesetwo molecules, only CS2 is non-polar, but PH3isn't polar.

Furthurmore, by finding out the structure, I can see thatCS2 is linear, and PH3 is trigonalplaner.

Therefore, what happens if two elements inside the molecule haveeletronegativity are 0, what should I do? Draw lewis structure?VSEPR? Electronegativity Charts?

Explanation / Answer

Polarity is dependent upon both the electronegativities of thebonding atoms and the molecular geometry in themolecule. With CS2, the C - S bond is polarized, but the moleculargeometry is linear, so the dipoles effectively cancel out. Thus itis nonpolar. With PH3, the P - H bond is polarized, and the moleculargeometry is trigonal pyramidal, with a net dipole towards thephosphorous (+ on the H, and - on the P). Thus it ispolar.

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