The noble gas electron configuration for barium (Ba) is [Xe] 6s2.
Here’s the explanation:
Barium has an atomic number of 56, which means it has 56 electrons. To write its noble gas electron configuration, we start by identifying the nearest noble gas that comes before barium in the periodic table. In this case, it’s xenon (Xe), which has an atomic number of 54.
Xenon’s electron configuration is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6. This accounts for 54 electrons.
After xenon, barium has two more electrons. These electrons go into the 6s orbital. Therefore, the noble gas electron configuration for barium is written as [Xe] 6s2.