Can someone please explain to me why magnesium and copper good electrodes please it's for my coursework b!
Hi Ronan! The reason why magnesium and copper are good electrodes is that they have a large difference in reactivity. If you studied the chapter on Metals and Non-Metals, you would have remembered that these four elements are ordered from most reactive to least reactive: Calcium, Magnesium, Zinc, Copper. This means magnesium loses its electrons faster than copper, and due to this, copper ions are more likely to accept electrons than magnesium ions. Therefore, electrons flow from the magnesium electrode to the copper electrode, creating an electric current.
These properties apply to any two elements (or compounds) so long as they have a large enough difference in reactivity. The bigger the difference in reactivity, the larger the electric current will be. This would also work if you're using two of the same element, as long as one of the ions are positively charged and one of the ions are negatively charged.
As a matter of fact, one of the elements/compounds doesn't have to conduct electricity (on their own), as long as a metal electrode is present so that the electrons can flow.
Check out this site for the reactivity series, which ranks elements from most reactive to least reactive: