[Polleke]

Dear all,

how would you define a heavy metal?

We all speak of heavy metals, but how would you define it ? Or better: what definition would you pick of someone asks you what a heavy metal is?

[Schrödinger]

There is no clear drfinition as such.
See http://en.wikipedia.org/wiki/Heavy_metal_%28chemistry%29

[bromidewind]

None of the international naming conventions have a concrete definition for "heavy metal", which has resulted in inconsistency in scientific literature, something that needs to be remedied. I found an article about the definition of heavy metals written by Dr. John H. Duffus, a toxicologist who is also a member of the IUPAC. I really like the statement that he makes at the end of the introduction.

Without care for the scientific fundamentals, confused thought is likely to prevent advances in scientific knowledge and to lead to bad legislation and to generally bad decision-making.

-<a href="http://iupac.org/publications/ci/2001/november/heavymetals.html">Heavy Metals - A Meaningless Term</a>

If a big safety watchdog like OSHA decided to strictly follow one of the <a href="http://iupac.org/publications/ci/2001/november/heavymetals_t1.html">definitions</a> of "heavy metals" involving toxicity, then they would probably prohibit the use of all heavy metals outside of laboratories. Most of the world's refineries rely on heavy metals to be used in making alloys, so if these were prohibited, then a large number of products, namely steel alloys, could not be produced. I agree with the statement that Dr. Duffus makes in his conclusion, that heavy metals should be defined based on their bioavailability, with as few exceptions as possible.

[abigail07]

Actually, I learned that lesson during my high school life. A heavy metal is a member of an ill-defined subset of elements that exhibit metallic properties, which would mainly include the transition metals, some metalloids, lanthanoids, and actinides. Many different definitions have been proposed, some based on density, some on atomic number or atomic weight, and some on chemical properties or toxicity.

[Polleke]

Actually, I learned that lesson during my high school life. A heavy metal is a member of an ill-defined subset of elements that exhibit metallic properties, which would mainly include the transition metals, some metalloids, lanthanoids, and actinides. Many different definitions have been proposed, some based on density, some on atomic number or atomic weight, and some on chemical properties or toxicity.

Looks a bit like the wikipedia definition

Anyway, its indeed hard to state what a heavy metal is when there is no real meaning or definition for this term.

And it doenst make it easier for me because I am working with copper and iron.. and I wrote those are heavy meatels, but hell, its not even sure or correct.

[stewie griffin]

Metallica, Megadeth, Pantera, Slayer, etc... 

[typhoon2028]

metals heavier than iron

[408]

Metallica, Megadeth, Pantera, Slayer, etc... 

If those are heavy metal, what are the actinides?   

[Fluoroantimonicacid]

Metallica, Megadeth, Pantera, Slayer, etc... 

If those are heavy metal, what are the actinides?   

They are a metal group.