What element has a noble gas notation (Xe) 6s2?

Barium has the noble gas configuration [Xe]6s².

You can learn about noble gas configurations at

http://socratic.org/questions/how-can-i-write-a-noble-gas-shorthand

To work backwards and find the element with a given configuration, you first find the noble gas in .

Xe is element 54.

Your element has two more electrons (and two more protons) than Xe. It must be element 56. Look in the Periodic Table, and

Element 56 is barium, Ba.