Why is zinc more reactive than copper?

We have all studied Chemistry and done our fair share of experiments. Most of our coursework has often revolved around metals, and this is no surprise. Metals are the most reactive of all elements, and involved in a major portion of everyday reactions. Some of these are more reactive than others.

Let us talk about copper and zinc then. In a displacement reaction involving the two, we see Zinc displacing the Copper; Zinc attains a pink layer of Copper, and the copper ion solution starts to fade. This is because Zinc is more reactive than copper, but why so?

Metals react by losing electrons, and this ease defines their reactivity. In this regard, they are reducing agents. A Zinc atom is larger in size than a copper atom. However, both Copper and Zinc have the same number of valence electrons i.e 2. This means that the Zinc has a lower electron density, and can lose its electrons more easily. Hence, it is more reactive. Metals can be arranged in a specific order called the ‘reactivity series’. This series is arranged in the order of increasing electron density. In this arrangement, Sodium is the most reactive (least electron density) of the metals, and Copper the least reactive (most electron density).

The experimental way of finding the reactivity of metals, is to react them with each other. The more reactive metal will perform the function of a reducing agent and give its electrons to the other metal. Hence, it would displace the other metal. To conclude, Zinc is more reactive than Copper due to its relative electron releasing power, and this is also verified experimentally.

This then is the simple explanation of the relative reactivity of metals. Try it out in your chemistry lab next time!