NOTHING RELATED TO THIS PUZZLE OR CACHE IS AT THE POSTED COORDINATES - They are simply coords for Dabney Hall, the building where most of NCSU's chemistry research takes place.
On the periodic table of elements, certain elements are classified as "metals". Metals are typically hard when in solid state, opaque, shiny, malleable, fusible, ductile, and have good electrical and thermal conductivity. Although no strict definition of "metal" exists, around 90 of the 118 elements on the periodic table are considered metals.
Of the metal elements, most of them are considered "heavy metals". Like "metal", "heavy metal" is a loose classification and scientists disagree on its definition. Metallurgists sometimes prefer using a metal's density (greater than 5 g/cm^3) as the defining factor in determining if it is a "heavy metal". Whereas physicists often prefer using a metal's atomic number (greater than 20) as the defining factor. We'll use the physicists' definition for the remainder of this discussion.
Many heavy metals are present in the earth's crust and commercially mined. However, about 1/3 of the known heavy metals can only be created in lab environments via artificial transmutation. Of the artificially created heavy metals, about 1/2 of them are highly unstable and rapidly decay with a half-life of less than 1 day.
Some heavy metals (like platinum) are very rare and considered very valuable. Others (like copper) are very common and used frequently in our everyday life. Still others (like protactinium) have no practical use outside of scientific research.
Heavy metals are often thought of with a negative connotation when it comes to issues of human health. However, while some heavy metals (like mercury) are highly toxic, some are essentially nutrients (like iron).
As you can see, there is significant variation even within the heavy metals, so using a simple defining criterion is very helpful in identifying them. Let's give some further examples of what elements are heavy metals, and what are not:
Tin is a heavy metal, but Phosphorus is not.
Europium is a heavy metal, but Sulfur is not.
Molybdenum is a heavy metal, but Krypton is not.
Palladium is a heavy metal, but Carbon is not.
Gold is a heavy metal, but Hydrogen is not.
Plutonium is a heavy metal, but Iodine is not.
Niobium is a heavy metal, but Oxygen is not.
Titanium is a heavy metal, but Argon is not.
Hopefully this discussion has given you a better understanding of heavy metals.
Oh... also, "heavy metal" is a genre of music.
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