• Question: Can you explain in Lamen’s terms the molecular theory?

    Asked by 08chayler to Andrew, Daniel, Hayley, Natalia, Peta on 16 Nov 2011.
    • Photo: Daniel Scully

      Daniel Scully answered on 14 Nov 2011:

      What do you mean by molecular theory?

    • Photo: Hayley Smith

      Hayley Smith answered on 14 Nov 2011:

      I’m not really sure this is what you’re after, but I’ll have a go…
      How it was explained to me at school was all to do with the Ancient Greeks. One day, they did a thought experiment (they were quite philosophical in their approach). The question they thought about was along the lines of “what is the smallest thing”? So you take some bread, half it, half it, half it etc etc until you’re left with something crumb sized – now it’s pretty difficult to half, right? Well then the Ancient Greeks supposed that there must be something, that was the smallest possible division of something – the greek word for this is atom.

      Now people have divided this even further into protons, neutrons and electrons.

      But molecular theory is to do with things on the “atomic” level and looks at how these hold together, looking at the “bonds” between them.

      Sorry if that’s not what you’re after!

    • Photo: Andrew Cairns

      Andrew Cairns answered on 16 Nov 2011:

      Are you after the theory of how we make compounds? ie how molecules are made?

      I’ll explain that the best way that I can!

      Everything is made up of atoms (atoms can be split, but I am going to ignore this for the moment). Around the nucleus in the atom there are electrons spinning around. Most elements are not happy with the number of electrons they have, so they will usually want to gain more or lose some.

      This is achieved either by donation or by sharing. When we donate electrons, we make charged ions, as some have more electrons (negative) than protons (positive) and the other ions are the opposite. These then attract each other very strongly to form compounds. Sodium Chloride (table salt) is an *ionic* compound.

      The other type of molecular bonding is through sharing. In water, the oxygen and hydrogen atoms share the electrons to form very strong bonds between them. This makes a stable compound, and the waters do not need to bond with anything else to be stable.

      With everything in chemistry, the true bonding is always in-between these two cases. Water has very different properties to salt, but they are both ‘compounds’.

    • Photo: Peta Foster

      Peta Foster answered on 16 Nov 2011:

      Hmm… if you mean kinetic molecular theory… then it is the theory that describes the behaviour of a gas made up of molecules (which it assumes take up no actual volume) and it assume these particles travel in straight lines and obey the laws of classical mechanics (so they move in straight lines but can be acted on my external forces). The theory also assume that all collisions are elastic (which means no energy is lost in the process) and that the molecules are charge neutral and have an average energy which is related to the overall temperature of the gas.

      With these assumptions they find that you get a certain range and distribution of velocities of the particles which when everything has been left for a while to settle down has been called a Maxwellian distribution.

      I hope this helps 😀

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