The concept of "weakest" metal is a bit tricky because it depends on what kind of weakness you're looking at:

* Strength: If we're talking about tensile strength, meaning how much force it can withstand before breaking, then Cesium is the weakest metal. It's so soft you can cut it with a knife.

* Melting point: If we're talking about melting point, then Mercury is the weakest metal. It's a liquid at room temperature.

* Reactivity: If we're talking about chemical reactivity, then Sodium and Potassium are very weak metals. They react violently with water and air.

So, there's no single "weakest" metal – it depends on what property you're measuring.