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So, today we’ll take a look at the secret corners of periodic table of chemical elements, by looking at the class of lanthanide metals that are quite active but at the same time are hard metals and have some unique properties.
Today we will focus on this metal called cerium, which is almost at the beginning of the lanthanide array. Cerium is quite an active metal, when exposed to the air, as time goes by, it gets covered with a layer of cerium oxide, and eventually may even completely oxidize and turn into oxide powder.
Hence cerium is stored in ampules or in an inert atmosphere, or coated with a layer of paraffin to protect from oxidation. Cerium is an expensive metal, I gave away $15 for 10 grams, but due to its high prevalence among the lanthanides it is the cheapest of them.
Cerium is widely used due to its pyrophoric properties, i.e. spontaneous combustion in air as dust.
To demonstrate this property, I'll break the ampoule that contains pieces of cerium.
In appearance the unoxidized cerium from the ampoule is a shiny metal, which has a crystalline structure at the break points.
Let's try and rub cerium on a file to see whether the bright sparks will be formed at the same time.
Honestly, I was expecting a bit more, like a huge amount of sparks, but you can’t fool chemistry. That’s why the Austrian chemist Velbash invented the alloy called ferrocerium which has a strong ability to form sparks.
You can see the composition of this alloy on the screen.
Ferrocerium is commonly called flint, which is used in lighters or camping flint.
Namely, the addition of other lanthanide metals and iron to cerium improves its properties and leads to the formation of bright sparks.
As time went by I now had a small handful of sawdust cerium; let’s try and light them using ferrocerium flint.
Cerium powder burns perfectly forming cerium oxide.
Now let's see what happens if we burn a piece of cerium with a burner.
In the air cerium gradually burns without a bright flame forming yellow cerium oxide.
By the way, this oxide is used in gas lamps.
The lamp gets covered with a mesh tissue that is impregnated with salts of cerium and other metals.
When the tissue is burning, cerium salts decompose and form cerium oxide which then glows when heated, illuminating everything around.

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