Adventures with Bismuth

I am very interested in elements and the periodic table and have been watching YouTube videos on the properties of some of them. One thing that I wanted to try was making bismuth crystals ... I have seen amazing crystals online. I asked for some bismuth for Christmas. See below for how it went!

About bismuth

It is a metal element with the atomic number 83 and symbol Bi. It is a heavy metal and is unusual as it is not toxic like many others in that part of the periodic table. It is slightly radioactive but not enough to harm you. It has a rainbow shiny oxide layer which makes the square crystals look amazing. 

How to get bismuth

You can actually just buy bismuth from Amazon. We ordered 1kg.

How to melt bismuth

Bismuth has a fairly low melting point (271.5C) and it is possible to use an old saucepan to melt it on the stove. Of course, my mum was not crazy about the idea of using one of her cooking pans, so I went to Emmaus to get a scrap pan from their metal skip. Melting the bismuth on the stove was pretty easy and it looked like mercury with rainbow colours in it. On the top I could see a crusty layer forming which I scraped off with some old cutlery (also from Emmaus!). This was slag and was the impurities in the metal.

We cooled the liquid and expected the crystals to form. Here is how it looked:

Problems

Even though we could see the crystals forming, it seemed impossible to get them out. The pan was too wide and the depth of bismuth too shallow. It kept setting in a lump and we needed to remelt it. This went on for quite a while and we knew we would have to come up with another way....

To solve the too-large pan problem, we decided to buy a crucible.

Unfortunately, we did not look too closely at what we were buying

Hint: Always check the measurements!

Despite the crucible being tiny, we decided to give it a go. We thought that we could pour in the molten metal and keep the heat on low, then turning it off so it cooled slowly enough to get some crystals.

Success!

I finally achieved my objective and you can clearly see the square crystals of bismuth! I will consider doing this again with a bigger crucible.