Since the evolution of the homo sapiens brain, individuals blessed with such a biological marvel have attempted to extract fundamental building blocks from the natural world in order to build tools with which to shape that world. Of course humans are not the only animals capable of making tools from the surrounding environment. That behavior has been observed even in crows (with that in mind I suggest we all be nicer to the crows; if Hitchcock's The Birds is going to happen, the crows will certainly be the organizers, and they might have cleverer plans than just poking our eyes out). But because of that particularly adept and curious brain, humans throughout history have delved ever deeper into what the fundamental building blocks of nature are, along the way developing new techniques and altogether new concepts for tools.Read More
Topics: pitting corrosion
Posted by Greg Spitz on Sep 16, 2015 8:24:00 AM
To begin, it must be said that while the term "rust" is defined as iron oxide and therefore rusting is something that can only happen to iron and iron alloys, asking whether or not aluminum "rusts" gets to an important question. Really the question is about corrosion but because aluminum is an element and not an alloy of iron, the question is more properly posed as "Does aluminum corrode?" Let's find out.
Chlorine is one of the most common elements found on Earth's crust. The name comes from the Greek word for light green, which is how the gas appears in elemental form. It has 17 protons and two stable isotopes giving it a standard atomic weight of 35.45, which makes chlorine the second lightest halogen. It also has the highest electron affinity of any element making it a very strong oxidizer. This means that chlorine will readily steal electrons from other elements. In fact the vast majority of chlorine found on Earth is in the form of the chloride anion (a chlorine atom which has already stolen an extra electron), which will form ionic compounds with many cations (like metals). It is in this form that humans are most familiar with chlorine, as in ionic compound sodium chloride, which we know of as table salt. Chloride ions are important to many chemical and industrial processes including the making of usable chlorine and sodium hydroxide, and desalination and testing of potable water.