What are Heavy Metals?
The metals that have higher density or higher atomic mass are known as heavy metals.
Now there are different definitions of heavy metals according to different researchers.
Because some researchers have defined the term heavy metals on the basis of metallurgy, some have defined it on the basis of physical properties as well as some researchers have defined it on the basis of chemical properties.
In this way, there are different definitions of heavy metals on the basis of different fields like metallurgy, physics as well as chemistry.
So there is still research work going on for the specific definition and classification of heavy metals on the periodic table.
But many researchers have a common criteria to classify a heavy metal on the basis of its density.
If a metal has a density more than 5 g/cm3, then it is considered a heavy metal.
Based on this criteria, you can get the following metals classified as heavy metals on the periodic table (see image below).
Mercury (Hg), Lead (Pb) and Bismuth (Bi) show the maximum characteristics of heavy metals.
Copper (Cu), Silver (Ag), Cadmium (Cd), Tin (Sn), and Thallium (Tl) show less characteristics of heavy metals.
And the rest other colored elements in the above periodic table show fewer characteristics of heavy metals.
List of Heavy Metals
List of heavy metals is mentioned below.
From these examples of heavy metals, you will get to know which metals show maximum characteristics, less characteristics and fewer characteristics of heavy metals.
| Atomic number | Name of Heavy metals | How much characteristics do these elements show like heavy metals? (Maximum, Less or Fewer) |
|---|---|---|
| 80 | Mercury (Hg) | Maximum |
| 82 | Lead (Pb) | Maximum |
| 83 | Bismuth (Bi) | Maximum |
| 29 | Copper (Cu) | Less |
| 47 | Silver (Ag) | Less |
| 48 | Cadmium (Cd) | Less |
| 50 | Tin (Sn) | Less |
| 81 | Thallium (Tl) | Less |
| 24 | Chromium (Cr) | Fewer |
| 25 | Manganese (Mn) | Fewer |
| 26 | Iron (Fe) | Fewer |
| 27 | Cobalt (Co) | Fewer |
| 28 | Nickel (Ni) | Fewer |
| 30 | Zinc (Zn) | Fewer |
| 42 | Molybdenum (Mo) | Fewer |
| 45 | Rhodium (Rh) | Fewer |
| 46 | Palladium (Pd) | Fewer |
| 49 | Indium (In) | Fewer |
| 77 | Iridium (Ir) | Fewer |
| 78 | Platinum (Pt) | Fewer |
| 79 | Gold (Ag) | Fewer |
| 84 | Polonium (Po) | Fewer |
External resources:
- Tchounwou, P. B., Yedjou, C. G., Patlolla, A. K., & Sutton, D. J. (2012, January 1). Heavy Metal Toxicity and the Environment. Heavy Metal Toxicity and the Environment | SpringerLink. https://doi.org/10.1007/978-3-7643-8340-4_6
- Hawkes, S. J. (1997, November). What Is a “Heavy Metal”? Journal of Chemical Education, 74(11), 1374. https://doi.org/10.1021/ed074p1374
- Heavy metals – Wikipedia. (n.d.). Heavy Metals – Wikipedia. https://en.wikipedia.org/wiki/Heavy_metals
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