Six metals so reactive that some burst into flame on contact with water. Tap a flame to see the exact colour each one burns, and why they behave this way.
LiLithiumBurns crimson red
Atomic number
3
Atomic mass
6.9
Soft enough to cut with a butter knife, and light enough to float on water — though it fizzes and gives off gas the moment it touches it. Used in rechargeable batteries.
Why so reactive? Every alkali metal has just one electron in its outer shell, and it's easy to lose. Losing that single electron is all it takes to react — the further down the group you go, the more loosely held that electron is, and the more violent the reaction.
1. Which alkali metal burns bright yellow-orange and is found in table salt?
2. Which alkali metal burns lilac/violet?
3. How many electrons does an alkali metal have in its outer shell?
4. Which alkali metal is soft enough to cut with a butter knife?