From my elementary knowledge of chemistry:

I had to go looking for Mercury and Lead and sure enough they look about right.

Column 1 reacts with water so you bet that'll hurt. Hydrogen needs a boost to start reacting with oxygen so no naked flame is recommended.

Anything in column 7 are desperate to rip electrons away from molecules so yes, permanent damage to your tongue and mouth.

Uranium is alright if you lick it once. A guy ate uranium cake once on TV.

The 'Please reconsider' lot seem to be a good way to die a horrible death by radiation.

Tc I believe is technetium which is radioactive and emits gamma rays, perhaps not soluable so stays in your body and you become gamma-man.