Classify the following elements as metal or noble gas: Argon, Iron, Copper, Krypton, Neon, Silver, Thorium, Radon, Helium, Xenon, Erbium, Tin, Protactinium
Argon - Noble Gas
 Iron - Metal
 Copper - Metal
 Krypton - Noble Gas
 Neon - Noble Gas
 Silver - Metal
 Thorium - Metal
 Radon - Noble Gas
 Helium - Noble Gas
 Xenon - Noble Gas
 Erbium - Metal
 Tin - Metal
 Protactinium - Metal