Wednesday, 24 April 2013
1.42 explain why substances with simple molecular structures have low melting and boiling points in terms of the relatively weak forces between the molecules
A substance with a simple molecular structure is one that contains only a few atoms in a molecule.
The intermolecular forces (between the molecules) are weak, so it doesn't take much energy- or heat- to break them- this means they will melt and boil under low heats, as even small amounts of heat energy are enough to break the bonds.
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Why are the intermolecular forces weak what makes them any weaker than a less simple molecule? Thanks
ReplyDeleteThis is because INTERmolecular forces (between atoms) are much weaker than INTRAmolecular (between molecules). Intermolecular forces are the forces within a simple molecule, but the more complex a molecule is the more stronger intramolecular forces it has, and therefore the higher the melting and boiling point.
DeleteYo Naresh, you've got inter and intra around the wrong way.
DeleteBut to answer your question Benedict, intermolecular forces don't include the physical sharing of anything like covalent ones; this means they are weaker than said covalent bonds and anything of that kind.
DeleteNaresh, you have your terms mixed up. When ice melts to form water, it is not the forces between the atoms (the covalent bonds) that breaks up to go to a liquid (you would then just have hydrogen and oxygen). Instead, the relatively weak INTERmolecular forces (the forces of attraction between each individual H2O molecule) are overcome, breaking apart the solid structure and freeing up the water molecules to become a liquid.
ReplyDeleteUrsarka is right, there is a really good webpage which describes the intra and intermolecular forces with simple analogy's.
ReplyDelete