Molecular Polarity Quiz

Study Notes

Understanding Polarity in Molecules

Water is a polar molecule, whereas the chemicals in butter are non-polar, leading to a lack of interaction between them.
A molecule is polar if it has asymmetrical electron distribution and is made up of different elements with a significant difference in electronegativities.
Electronegativity is the ability of an atom to attract shared electrons, and it increases from left to right and decreases from top to bottom in the periodic table.
For a molecule to be polar, it needs to have two different elements with an electronegativity difference of 0.5 or greater.
Polarity results in a partially negative charge on the more electronegative part of the molecule and a partially positive charge on the less electronegative side.
Geometrical asymmetry is also necessary for a molecule to be polar.
Molecules with polar bonds may not be polar themselves if the symmetry of the bonds cancels out the asymmetry of the charges.
Polarity is indicated by a dipole moment, which is a separation of the charge around the molecule into a more positive and a more negative area.
Liquids made up of polar molecules are effective at dissolving solids composed of polar or ionic compounds.
Ionic solids involve a complete transfer of electrons, creating two charged ions, and are an extreme form of polarity.
The arrangement of partial positive and partial negative charges in water is at its lowest energy state when they line up together, positive to negative, into a liquid crystal.
The strength of surface tension in water depends on intermolecular forces that pull molecules of a liquid together, and cohesive forces minimize surface area in the liquid.