Wow! I never thought some metals would dramatically react on water... pretty impressed!
I'm a chemistry teacher and have to say that they took away the excitement that should be in any video of the alkali metals. The video's showing of Sodium in water was a let down. I've taught this with an approx. 1 cm cubed piece of sodium that I've made cuts into all sides of to expose more surface area and upon dropping it into a bucket of water made such an explosion that it frightened nearby classrooms and busted the bucket. Another teacher did a similar demo with a smaller piece of sodium and without exposing more surface and caught the grass on fire.
This my friends, is why Chemistry is the bomb-digity.
Let's try cesium, he said.
cesium is made of awesome!
Strictly speaking, francium is the end boss of the alkali metals, but really you need the IDDQD of life to get an appreciable amount of it, so cesium will have to do.
"You can see that things gradually become more terrifying as we move down the group" Indeed.