Bullets have Pb, and Cu, both known to be very bad when introduced to the bloodstream, in this case quickly.

Whether something is a chemical weapon depends also on use, not only on content.

https://www.opcw.org/our-work/what-chemical-weapon

So yes, any of the above chemicals if they were to be used to cause harm via their toxic properties, would be chemical weapons according to OPCW.

WP white phosphorous is actually a chemical weapon when used against people. It is an anti material weapon and used for smoke screens. But read up on the use of WP in fallujah.

The "Chemical Weapons Convention" bans tear gas for use in warfare, so that could easily be considered a chemical weapon.

White phosphorous is borderline; if it wasn't already restricted by incendiary weapons rules (Geneva convention covers use against civilians, Convention on Certain Chemical Weapons covers other use) it would probably be restricted by chemical weapons rules.

Tear gas is _clearly_ a chemical weapon (or a class of chemical weapons, really), and its use is banned in warfare by international treaty. Many countries do allow its use on civilians outside the context of warfare.