Wednesday, 1 May 2013

2.8 explain the relative reactivities of the elements in Group 1 in terms of distance between the outer electrons and the nucleus.

Group one elements are more reactive further down the group.

Group one elements need to loose an electron- the one on the outer shell- to react. Electrons are held to an atom by the protons in the nucleus. If an electron is close to the nucleus the force holding it in will be very strong, if it is further away it will be weaker.

So bigger atoms (towards the bottom of the group) with the outer orbital far from the nucleus will loose their electron more easily: this means they react more easily/quickly/more/vigorously.

Smaller atoms with the electron closer to the pull of the nucleus (at the top of group one) will be less reactive as it takes more to lose the electron.


  1. Why does the element with the outer shell electron(s) further from the nucleus produce a more vigorous oxidation reaction because surely those with nearer electrons require more energy to break them away so wouldn't that reaction be more vigorous!?!

    1. This is just a theory but- the more reactive elements are bigger right? Well for example if you throw a chunk of sodium into water compared to a tiny bit of sodium into water, the chunk of sodium produces a more vigorous reaction. So the bigger elements produce a more vigorous reaction because of their larger size. Correct me if i'm wrong.

    2. When we talk about size in terms of chemistry, we are not talking about physical size we are talking about the size of the atoms within the substance. For example a 20x20 cube of potassium is bigger than a 20x20 cube of sodium. As it contains a great number of orbital shells, protons and electrons and therefore each individual atom is bigger. With metals, they want to lose electrons and so as the attraction force between the electrons on the outermost shell of the atoms and the positive charge of the protons within the nucleus (centre) of the atom decreases as the atoms become larger ( more orbital shells block the force of attraction) it is easier to lose an electron therefore making it more reactive.

    3. Do not confuse vigourosity with lenght of reaction

  2. I believe it is because the reaction is very short as it is very easy to lose the electron the further down the table you go so whilst the total energy given off is less it is given off over a much shorter period of time hence the reaction is more vigorous

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