By definition, elements, whose atomic nuclei have the same number of protons, and compounds, which have two or more elements bonded together, are both pure substances. Not to confuse the “pure substance” term with chemical “purity” in the analytical sense, what matters more is that pure substances can be anywhere on the spectrum in terms of how they impact humans and the rest of nature. When evaluating chemical elements and compounds from this point of view, the following classification may prove useful.
1. Not Quite Perfect Superheroes: Essential Life-Giving Substances
At first glance, water seems like the perfect superhero molecule. The molecule’s properties are quite special. Fairly resistant to temperature changes, large bodies of water slowly absorb or release heat to the atmosphere and nearby coast. During photosynthesis, water can lose electrons to excited chlorophyll molecules, creating oxygen for respiration and acidic ions that set up a potential difference invested in…
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