Is NaCl Polar or Nonpolar?

Answer: NaCl is a polar molecule due to the large electronegativity difference between sodium (.93) and chlorine (3.16). In fact, the difference is so great that this is considered an ionic bond with the two pieces nearly equivalent to ions. This causes the molecule to bond with itself in very strong crystal lattice conformations. 

Due to these extremely strong bonds, the molecule has a melting point and boiling point of 801˚C and 1405˚C, respectively. These are much larger than the boiling points present in other intermolecular forces such as hydrogen bonding (as seen in H2O). Therefore it is no surprise that the compound forms a crystal lattice solid at standard pressure and temperature. Within this lattice structure sodiums and chlorines alternate between molecules so that attractions can be both in the ionic bond and across the large electronegativity difference b/t different molecules. In fact, chlorines attraction to sodium's one valence electron is so strong that the molecule disassociates in water into Na+ and Cl-. These ions float around within polar substances independently and indeed are typically not very reactive. In fact, when you simply throw in regular sodium or other alkali metals into these environments, the reactions are typically very violent. The sequence of animations at the end of the presentation at the link in the previous sentence illustrates this principle extremely well.

NaCl Ball and Stick Diagram
NaCl Ball and Stick Diagram. Created with MolView
How is NaCl (sodium chloride) utilized in the real world?

The first major place many will recognize NaCl is as the constituent of table salt which adorns many dining tables around the world. In fact the salt shards are at their core simply lattices of NaCl. Sodium chloride determines the salinity within the ocean water and thereby regulates the extracellular environment of many multicellular organisms. Some have become tolerant to high levels of salinity and other organisms actively expend energy to push this salt against its gradient. Salt also helps to add friction and de-ice the roads during major winter weather storms. NaCl also finds use in the production of many other salts/chemicals for industrial applications.

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