Coatings

The behavior of magnesium as a "sacrificial metal" (or sacrificial anode) is interesting beyond its value as a protective metal. Based on magnesium's position on the activity series or in the SRP table, it should be a very reactive metal. It should, in fact, reduce water to hydrogen gas just like sodium, potassium, barium and so on. But it does not appear to do that.

In the Periodic Properties experiment last semester we saw that magnesium just barely reacted with boiling water. What is the problem with magnesium???

So the behavior of magnesium indicates that sometimes our predictions about reactivity will be faulty because of corrosion! No matter how you look at it, rust is a problem.