Which element is represented by the electron configuration [Kr] 5s^1?

The electron configuration [Kr] 5s^1 indicates that the element has its outermost electron in the 5s subshell and that it is following the krypton core. The notation [Kr] represents the electron configuration of krypton, which includes a complete octet up to the 4p orbital. After krypton, the next available subshells are 5s and 4d.

When looking at the periodic table, the element with an electron configuration of [Kr] 5s^1 corresponds to an atomic number of 37, as it is the first element in the fifth period that begins filling the s subshell. The element with atomic number 37 is rubidium (Rb).

Rubidium is an alkali metal, which is located in group 1 of the periodic table, characterized by having one electron in its outermost shell, which aligns with the 5s^1 configuration. This configuration indicates that it is more reactive due to the presence of this single valence electron, typical of alkali metals.

Strontium (Sr), on the other hand, would have an electron configuration of [Kr] 5s^2, having two electrons in the 5s subshell