Does this sound correct?

I believe that reactivity of elements will increase going down the groups on the periodic table. As the outer electron shell becomes further away from the nucleus, the electrostatic attraction on the electrons decreases, less energy is required to make bonds with other elements. Therefore, more energy can be used in the reaction.

Sound correct?

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sounds oversimplified for s-block elements and plain wrong for all the rest.

Ever heard of fluorine....? lol

Rats! Could you sort of explain the order in which elements become more reactive...and why?


that's a very good simple question -)
but the detailed answer is not so succinct, I'm afraid lol

Ultimately, the answer to "what makes something reactive"
comes down to "energy".

Something will react (ie, some starting reactants turn into some final products) if the products are overall lower in "energy".
The branch of science which looks at this is called Thermodynamics.

A spontaneous reaction isn't possible in the first place if it's not thermodynamically feasible (ie, won't lead to a state of lower energy)

The next thing to consider, if it turns out a reaction is possible in the first place, is - how quickly will it happen?
This area is called "kinetics". It may be, you see, that even though the end products would be much lower in energy, it takes aaaaaaaaaages for the reaction to happen (centuries!), becuase the energy required to rearrange the molecules into the products is a big hurdle.
(an example is graphite versus diamonds...... both a different arrangements of carbon atoms.... and diamonds are lower in energy, thermodynamically in princple, a lump of coal should happily turn into a diamond.... but kinetically, it doesn't happen)

So - those are the ultimate principles behind it all.....

Now to get down to specific trends in how reactive specific elements are.....
something you should remember is that something is always reacting *with something else* ..... so you have to consider the overall energy of all the reactants versus all the products....
But if you keep one reactant the same (eg, compare the reactivity of different metals with, say, cholorine), then you can see trends and patterns happen.

Most fundamentally, reactions involve re-arranging electrons between the reactants, to form new bonds in the products...

So you have to examine how easy it is to break the bonds in the reactants (eg, how easily a certain element will give up it's electrons .... or accept new electrons),
and you have to examine how stable the new bonds in the product will be.

you can draw out a thermodynamic cycle for see all the different energies
eg if sodium metal is gonna react with chlorine gas

you gotta separate all the sodium atoms in the solid metal,
and you gotta break the chlorine-chlorine bonds in the Cl2 gas,
you gotta strip off one electron from each separate Na atom to form Na+,
and you gotta transfer each of those electrons to a Cl to form a chloride ion,
and then you gotta put all the Na+ Cl- ions back together in an ionic lattice, and see how much energy you have lost or gained by the end of it all.

You could look at all the same steps for LiCl, for KCl, for RbCl, for CsCl (ie all the alkali metals),
and you'd see how the energies change from element to element for the different steps.
(eg, to separate the metal atoms, and then to ionize them)

And then if you were smart, you could explain the different changes in terms of atomic structure - the charge on the nucleus and the configuration of the electrons in each element....

hours of fun, in fact -)

Actually, I could have sworn that I read someplace that graphite is a more stable form of carbon than a diamond is. Over a period of a near eternity, diamonds will turn into graphite. (It's just that this transformation is so freaking slow that there is zero chance of seeing it occur).

oh, is it the other way round?

I seem to remember the difference being "4kJ/mol", if I remember my textbooks correctly....
....but that would probably have been calculated by doing things like determining the heat of vapourization of diamonds and stuff, which is bound to me a bit tricky to measure... -)

I need to make a website dedicated to ranting about the word "reactive". What do you mean reactive? Do you mean reactive for oxidation? Reduction? Acidity? Basicity? ligand substitution? nucleophillicity? Or do you mean reactive to skin? to paper? to air? to water?

The rules for reactivity are simple.

On the periodic table...
Further to the left---easier to lose electrons
Further to the right---easier to take electrons
Further to the bottom---easier to lose electrons
Further to the top---harder to lose electrons

Also, the semimetals are the group of stuff that is most unable to lose or grab electrons as their top-left and bottom-right position neutralized the abilities to lose against that to grab.

To the right-top of the semimetals (espec. Fluorine) are more reactive by more easily grabbing electrons.
To the left-bottom of the semimetals (espec. Cesium, Francium) are more reactive by more easily losing electrons.

Your assuming he is talking about reactive with respect to oxidation and reduction. Thus the problem with the term reactive.

Of course, he is talking about the positions of the shells.

Diamond - Graphite

Graphite is the "preferred" state of carbon at temperatures below like 300C at 1 atm (I can't find the ellingham diagram off hand so don't quote me on that value). However, since the C-C bond is so strong in either polymorph, its difficult to transform in either direction (the kinetic considerations). Hence why your grandmas pretty diamond isn't grey or a gas (CO2) from years of exposure to 30C and 1 atm.

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