If I understand the annotations on this, YouTuber ironnica’s only posted video, correctly, the footage was produced by a New Jersey educational media company in 1991, and the delightfully British narration more recently by somebody associated with the UK’s Open University. In any case, it is a perfectly concise, interesting, and entertaining demonstration of the increasing reactivities of the group I metals lithium, sodium, potassium, rubidium, and cesium. Francium, the heaviest and theoretically most reactive of the alkali metals, is not included because its highly unstable nucleus does not persist long enough to allow for the accumulation of weighable quantities of the bulk element. [via Geekosystem]