Final answer:
The configuration [Kr]5s¹ refers to the element Rubidium (Rb), which is in period 5, group 1, and located in the s-block of the periodic table.
Step-by-step explanation:
The electron configuration [Kr]5s¹ refers to the element Rubidium (Rb). Let's break down the details:
- Symbol: Rb
- Period: 5, as the outermost electrons are in the fifth energy level (5s).
- Group: 1, as it has one electron in its outermost s-orbital.
- Block: s-block, because the last electron added is in an s-orbital.
The electron configuration indicates the last electron is in the 5s orbital, which corresponds to the first group of the periodic table. Rubidium falls into the s-block, which includes all the elements with their final electrons in an s-orbital. As an element in period 5 and group 1, it has properties consistent with the alkali metals, which are notable for their single valence electron in the outermost s-orbital making them highly reactive.