What occurs when lithium is mixed with water?

When lithium is mixed with water, it reacts to produce lithium hydroxide and hydrogen gas. The reaction can be vigorous, and it typically results in the formation of bubbles of hydrogen gas, which is released during the process. This is represented by the equation:

[ 2 \text{Li} + 2 \text{H}_2\text{O} \rightarrow 2 \text{LiOH} + \text{H}_2 \uparrow ]

Lithium is less dense than water, which means it will float on the surface. As the reaction occurs, you can observe that it moves around on the water's surface, bubbling and fizzing as hydrogen gas is produced. The lithium metal will gradually dissolve, but it doesn't just disappear instantly; rather, it reacts and becomes part of a solution (lithium hydroxide).

The option stating that lithium floats steadily and disappears gradually oversimplifies the process, as the vigorous bubbling from hydrogen gas is a significant and noticeable aspect of this reaction. Nonetheless, the resulting behavior—floating while producing bubbles—characterizes what generally happens when lithium meets water.