Zirconium (Zr) is located in Group 4 of the periodic table. As a general rule, elements in Group 4 have 4 valence electrons. However, zirconium is an exception to this rule due to its electron configuration.
The electron configuration of zirconium is [Kr] 5s^2 4d^2. From this configuration, we can determine that zirconium has a total of 4 valence electrons. The 5s^2 electrons are considered the outermost or valence electrons in zirconium.
Therefore, zirconium has 4 valence electrons.