Here's how to determine the noble gas notation of rubidium (Rb):

1. Find Rubidium on the Periodic Table: Rubidium is in Group 1 (alkali metals) and period 5.

2. Locate the Previous Noble Gas: The noble gas that comes before rubidium is Krypton (Kr).

3. Write the Noble Gas Symbol: Start the notation with the symbol of the previous noble gas in brackets: [Kr]

4. Determine the Remaining Electrons: Rubidium has 37 electrons. Krypton has 36 electrons. Therefore, rubidium has one extra electron.

5. Add the Remaining Electrons: The noble gas notation for rubidium is: [Kr] 5s¹