Radium has two valence electrons.
Explanation: Radium is an alkaline earth metal, located in group 2 of the periodic table. Elements in this group typically have two electrons in their outermost shell, which are referred to as valence electrons. These electrons are responsible for the chemical behavior of the element and determine how it interacts with other elements. In the case of radium, its electron configuration is [Rn] 7s2, indicating that there are two electrons in the outermost shell (the 7s subshell). This characteristic helps to explain radium’s chemical reactivity and tendencies.