Which is the more metallic element: As or Sn?
Well, probably tin.......
Metallic character decreases across a Period (a row of the Periodic Table) from left to right as we face the Table, and increases down a Group, (a column of the Periodic Table). You compare a Group 14 element from the fifth Period, tin, with a Group 15 element from the 4th Period, arsenic.
And as with any other such proposition, the chemist must interrogate the properties of the elements to assign metallic character. Elemental tin is a shiny, malleable material that readily forms cations; on the other hand, arsenic is more molecular, and tends to form anions.....On the basis of these data, we would clearly place tin under the metals umbrella, and arsenic under the umbrella of non-metals.