A chemist passed an electric current through a molten potassium hydroxide and
isolated a bright, shiny reactive substance. He claimed the discovery of a new element,
which he named potassium. Before the advent of modern day instruments, what is the
basis on which one could claim the substance is an element?
Before the advent of modern-day instruments, there were several criteria on which one could base the claim that a substance is an element:
1. Chemical properties: The chemist in this case observed that the substance obtained from the electrolysis of molten potassium hydroxide was bright, shiny, and reactive. This observation suggests that the substance possesses unique chemical properties that distinguish it from other known substances.
2. Consistency: The chemist would have repeated the experiment multiple times and obtained similar results each time. Consistency in the properties and behavior of the substance reinforces the belief that it is a distinct element.
3. Lack of decomposition: The substance would not decompose further into simpler substances under normal conditions. Elements are fundamental building blocks of matter and cannot be broken down into simpler substances through chemical reactions.
4. Absence of impurities: The chemist would have taken precautions to ensure that the substance obtained was free from impurities. The presence of impurities can alter the properties of a substance, making it difficult to determine if it is a pure element.
5. Comparison to known elements: The chemist would have compared the properties of the new substance to the properties of known elements. By finding similarities or differences, they could assess whether the substance is unique and distinct from any other known element.
Based on these criteria, the chemist likely concluded that the substance he obtained was a new element and named it "potassium." However, it is essential to note that in modern times, advanced tools and techniques, such as spectroscopy and mass spectrometry, are used to provide further evidence and confirm the elemental identity of a substance.