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  • N&PD Moderators: Skorpio

I'd like to learn more about Chemistry.

MedicinalUser247 said:
Do you know the difference between Polar v.s. Non-Polar @Skorpio ?
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First we need to get the concept of electronegativity. This is an atomic property where certain atoms attract electrons/electron density.

A polar compound is asymmetric, with one end having an atom (or a few atoms) significantly more electronegative than the other end. This causes the molecule to have a partial charge, with one end being more negative and one end being more positive.

Water is an example of a polar molecule, with its two hydrogens having a partial positive charge and the oxygen having a negative charge. Due to this polar molecules are often hydrophilic.

Non-polar molecules do not have a charge difference in the molecule. They are made of molecules with little or no difference in electronegativity. Propane is an example of a non-polar molecule.

Non-polar molecules tend to be hydrophobic.
 
Water, ethanol, acetone are fairly polar molecules. Likes dissolve likes. A polar solid like urea will dissolve in polar solvents.
Then in the middle you have your chloroform, methylene chloride. Diethyl ether is weakly polar.
THe non polars are hydrocarbons like @Skorpio said propane, hexane, octane, toluene, xylenes.

These are reasons why substances are immiscible or insoluble because of polarity differences.
My old advisor said dielectric constant is a measure of polarity maybe. iirc.
or the chromatographic series of eluents ranks solvents according to polarity.
 
Be careful with symmetry attributes. Because there's an entire expertise of chemistry using Group Theory and symmetry properties of molecules to calculate energy of molecular orbitals. Like water had a C2v point group which means it has a rotational axis 180degrees and 2 mirror planes of symmetry as well as an identity operation. You may also use spectroscopy to determine the energy gaps between orbitals based on electronic transitions to an excited state. Also is rotational (microwaves), vibrational (Infrared), and as mentioned electronic (UV/Vis) spectroscopy. reference to The Born-Oppenheimer approximation
 
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