1. Find Radium's Atomic Number: Radium has an atomic number of 88, meaning it has 88 protons and 88 electrons.
2. Locate the Preceding Noble Gas: The noble gas that comes before radium on the periodic table is radon (Rn), which has an atomic number of 86.
3. Write the Noble Gas Symbol: The noble gas configuration starts with the symbol of the preceding noble gas in brackets: [Rn]
4. Add Remaining Electrons: Radium has two more electrons than radon (88 - 86 = 2). These two electrons go into the 7s orbital.
Therefore, the noble gas configuration of radium is: [Rn] 7s²
