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Do not repeat the experiments shown in this video!
So today I want to tell you about the heaviest metal on earth – Osmium, it has the highest density of all of the metals.
In the periodic table of chemical elements osmium is in the 8th group, under the atomic number 76.
In addition to having the highest density of all the metals, another one of osmium’s traits is its color as it has a pronounced bluish tinge. As an example, if we compare it with a drop of iridium, you can easily notice the blue color of the droplet of osmium, which weighs one gram.
By the way, iridium takes the seconds place of the highest density metals and it was pretty close as the density of it differs by only one tenth of a percent from that of osmium. You may also notice the small size of the droplet of osmium weighing 1 gram in comparison with my finger.
On this massive photo I compared the density of different metals, the mass of each of them is equal to one gram. We begin with osmium with the highest density of them, then it is iridium, then lead, cobalt, iron, tin, yttrium, aluminum, magnesium, and finishing with sodium whose density is almost the same as that of water.
On this photo you can see how largely the density of the 2 metals can vary. Looking at the physical properties, osmium is very fragile and at the same time a fairly hard metal, the hardness of which on the Mohs scale is comparable to quartz.
Because of this property it is used in the tips of some expensive fountain pens. However, due to its hardness and brittleness osmium is effectively very badly suited for processing, so you’re unlikely to find any jewelry of this metal.
Nonetheless, to get some aesthetic pleasure you can look at these beautiful single crystals of osmium, which have a very pronounced grain structure.
These crystals were obtained by the method of gas transport and have an extremely high purity. I would like to thank the author of the website periodictable.ru for providing these unique samples of osmium for our shooting. These crystals have very little practical applications, though you can obtain very pure compounds of osmium from them.
Nowadays, osmium is produced mainly as a byproduct from the production of either copper or nickel. This metal is one of the rarest, there are about 50 parts of osmium per trillion parts of the earth's crust. According to some data, osmium is considered to be the most rare non-radioactive metal on Earth.
From the chemical point of view, osmium is a very stable metal. The powder of osmium reacts very poorly with the concentrated nitric acid and aqua regia.
However, when exposed to air osmium powder can oxidize to a highly toxic osmium tetroxide, hence osmium powder is stored in sealed ampoules. When heated, the powder of osmium can catch fire, forming burning particles and once again the toxic osmium tetroxide.
For the first time on YouTube you are now seeing the combustion of osmium in air. Also, if a drop of osmium is heated in air, it will at first become shiny, because at high temperatures the resulting osmium tetroxide evaporates from the surface of the metal.
However, during cooling, the bead of the metal gets covered with a dark film of osmium oxides of different oxidation states, which gets a crystal-like appearance.
Osmium tetroxide, formed by the reaction of osmium and oxygen, according to some sources, has the smell of garlic (don’t add it to your cooking please!), and even in spite of all its toxicity has several uses.
For example, the osmium tetroxide is used in organic synthesis, in particular for the reaction of Lumio-Johnson which you can on the screen now.
In addition, this substance is used as a dye in microscopy, in forensics to identify fingerprints, and also as an intermediate product in the production of pure osmium from ore. Pure osmium is now rarely used because of its high cost and even then only in the form of a powder, for instance, for experimental research.
By the way, it’s quite interesting that in the early missions of the space Shuttle they had spectrometers that used mirrors coated with osmium as this metal reflects ultraviolet radiation 2 times better than gold.
In the end, we can say that this rare metal osmium, despite its unique high density, is still not as common in applications, such as, for example, gold. The main reason is the toxicity of its tetroxide, and then the high price.