Answer:
Ba: 1s² 2s²2p⁶ 3s²3p⁶ 4s²3d¹⁰4p⁶ 5s²4d¹⁰5p⁶ 6s²
Step-by-step explanation:
Step 1. Locate barium in the Periodic Table.
It's in Period 6, Group 2: Element 56 (highlighted blue in the Periodic Table below).
Step 2. Add 54 electrons to the energy levels
You add then in the order shown in the diagram below.
The complete electron configuration is:
Ba: 1s² 2s²2p⁶ 3s²3p⁶ 4s²3d¹⁰4p⁶ 5s²4d¹⁰5p⁶ 6s²
n = 2 + 8 + 8 + 18 + 18 + 2 = 56
