Building the series
We have now gathered four sets of observations. It should be clear by now that all four give the same order.
| Observation | Most reactive | Least reactive |
|---|---|---|
| With air | Na, Mg burn readily | Ag, Pt, Au not at all |
| With water | Na with cold water itself | Ag, Pt, Au not even with steam |
| With dilute acids | K, Na, Ca violently | Cu not at all |
| With salt solutions | Zn displaces Cu | Cu does not displace Zn |
The same names in all four
In every observation it is metals like Na and K at the top and Cu, Ag, Pt and Au at the bottom. The metals can therefore be arranged in a single order.
The activity series
The series obtained by arranging metals in descending order of their reactivity is called the activity series.
The activity series has been built up on the basis of those observations and other data besides. It is of great importance in the study of chemistry.