Why are some chemicals more reactive?

[nhmllr]

So in high school we learned that chemicals with very few valence electrons want to get rid of them so that they can have a full outer shell, or if they only need a few more to get a full outer shell then the desperately try and get them. The teacher made an analogy that the atom really wants to have a full outershell, and the closer it is to achieving that the more reactive it is.

This answer does not appeal to me. Atoms do not have hopes and dreams. What force makes atoms work to get outer shells?

Thanks

 

[nathan444]

I can't give you a particularly in depth answer but I can tell you this.

If an atom can get a full outer shell it becomes more stable.

The positive electromagnetic force of the protons in tue nucleus is what draws electrons to an atom, however, the more rings of electrons you have around the nucleus, the more they repel and counteract the force of the nucleus, this is known as electron shielding.

In addition to electron shielding you have the fact that the more rings of electrons you have the further the new electron will be from the nucleus.

Both of these reasons combined account for why smaller group 7 elements such as fluorine are highly reactive (low electron shielding and distance means an electron is gained easier).
AND
It is the reason why small group 1 elements such as lithium are less reactive than larger ones (low electron shielding and distance makes it harder to lose an electron)

I hope that helped :)

 

[Khashishi]

The binding energy in a reaction is due to the coulomb potential arising from the arrangement of all the electrons and nuclei in the compound. Full shells are more stable because, roughly speaking, for higher shells, the electrons spent more time farther from the nucleus. Full shells let more electrons be closer to the nucleus. Of course, it's really more complicated due to electron-electron interactions, which gives rise to shielding.