1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s²

Let's break it down:

* 1s²: The first energy level (n=1) has one subshell (s), which holds 2 electrons.

* 2s² 2p⁶: The second energy level (n=2) has two subshells (s and p), holding 2 and 6 electrons respectively.

* 3s² 3p⁶: The third energy level (n=3) has two subshells (s and p), holding 2 and 6 electrons respectively.

* 4s² 3d¹⁰ 4p⁶: The fourth energy level (n=4) has three subshells (s, d, and p), holding 2, 10, and 6 electrons respectively.

* 5s² 4d¹⁰ 5p⁶: The fifth energy level (n=5) has three subshells (s, d, and p), holding 2, 10, and 6 electrons respectively.

* 6s² 4f¹⁴ 5d¹⁰ 6p⁶: The sixth energy level (n=6) has four subshells (s, f, d, and p), holding 2, 14, 10, and 6 electrons respectively.

* 7s²: The seventh energy level (n=7) has one subshell (s), which holds 2 electrons.

This notation describes the arrangement of electrons in barium's orbitals.