Question

Which of the following elements would you expect to be least metallic? Rn, Cs, Fr

Answer 1

Use periodic table: more metallic character goes to the left and in upward direction while going to the right and in the downward direction will lower it, basically, This makes it easier to form positive ions - the characterisitic of a good metal.

In the case of Rn, Cs and Fr, according to the above, Cs and Rn are on the period 6, and Fr it's on period 7. However, Rn it's a noble gas, it's on group 18 of the table, while Fr it's on the group 1, alkali metals. So, Although Fr is on a lower period, it's more metallic than Rn cause Rn is a noble gas.

The least metallic is Rn.

Hope this helps