5 Tests to Classify a Substance as Molecular Polar, Non-Polar, Ionic, Metallic, or Covalent Network
1. Does it have a high melting point?
Published in
2 min readOct 28, 2016
- If a substance has a relatively low melting point (below 400ºF), then it is either molecular polar or molecular non-polar
- If a substance has a high melting point, then it is either metallic, covalent network, or ionic
- The stronger a substance’s bonds, the higher its melting point
2. Does it conduct electricity as a solid?
- Only metallic substances conduct electricity as solids
3. Is it soluble in hexane?
- Only molecular nonpolar substances dissolve in hexane
- Like dissolves like, and since hexane is a nonpolar liquid, only molecular nonpolar substances dissolve in it
4. Is it soluble in water?
- Both molecular polar and ionic substances dissolve in water
- Since water is molecular polar, like dissolves like
- Ionic substances also dissolve in water because they dissociate into ions
5. If it is soluble in water, then does it conduct electricity as an aqueous solution?
- Only ionic substances conduct electricity in water because they are the only ones that dissociate into ions that can allow the movement of electrons
- Molecular polar substances remain intact and do not conduct electricity because they are not ionized
****Some Final Notes****
- Covalent network substances like diamond and sand are resilient and don’t pass any of these tests
- Metallic substances have varying melting points, but they are the only ones that conduct electricity as solids
- Solubility tests are best for distinguishing between molecular polar and nonpolar substances
- Ionic substances have the strongest bonds (ionic bonds) and therefore have the highest melting points
