Short Answer 
Stability refers to the strength of an element’s atomic nucleus, while reactivity indicates its tendency to engage with other elements. Iron is the most stable element due to its efficient nuclear binding, whereas Fluorine is the most reactive, known for its strong tendency to gain electrons and react with other elements.
Step 1: Understand the Concepts of Stability and Reactivity
The terms ‘stability’ and ‘reactivity’ are critical when assessing the power of elements. Stability refers to how well an element’s atomic nucleus holds together, while reactivity indicates how readily an element reacts with others. In the context of traditional elements, we usually consider these aspects to determine their strength and influence in various chemical processes.
Step 2: Identify the Most Stable Element – Iron
When we talk about stability among elements, Iron stands out as the most stable. This is measured by its binding energy, where its nucleus consists of a focused ratio of protons and neutrons totaling 56. This configuration allows Iron to release significant energy when formed, making it resistant to disassembly into its smaller components. Consequently, Iron is often viewed as having the greatest stability in the realm of traditional elements.
Step 3: Identify the Most Reactive Element – Fluorine
On the reactivity front, Fluorine is the most potent element. Known as the strongest oxidizing agent, it readily reacts with nearly all other elements in the periodic table. Its high electronegativity contributes to its reactivity, as it seeks to gain electrons. Therefore, when looking at traditional elements, Fluorine embodies the highest reactivity, making it the most powerful in that context.