"The subject of this film is iodine, an element in the halogens group. At room temperature, iodine is gray flakes with a metallic shine. But even when just heated gently, iodine gives off a violet gas. That is where the name of the element is from - it is derived from the Greek word ""ioiedis"" which means violet.
Like all halogens, iodine forms diatomic molecules. They are held together by van-der-Waals forces and form a regular molecular solid. If iodine is lightly heated, it begins to sublimate. That means it turns from a solid physical state into a gaseous state. If the iodine gas comes into contact with a cooled object, for example a cooled test tube, it resublimates again. Solid iodine then forms on the cooled test tube in needle-shaped crystals.
This film shows different reactions that involve iodine."