What is the chemical property of potassium when placed in water?

When potassium is placed in water, it exhibits a highly reactive chemical property. Potassium is an alkali metal, and it reacts vigorously with water to form potassium hydroxide and hydrogen gas. This reaction is exothermic, meaning it releases a significant amount of heat. The heat generated is enough to ignite the hydrogen gas released, often resulting in flames.

Additionally, due to its low density, potassium tends to float on the surface of the water initially. As the reaction progresses, the release of hydrogen gas forms bubbles that can cause the potassium to move rapidly across the surface. The fact that it ignites during this reaction highlights not just its reactivity, but also the energy involved in the process. Thus, the characteristic of potassium floating and igniting when in contact with water accurately captures its chemical behavior in this situation.