It has to be Lead. These days the most hated, but still one of the most useful. Nothing comes close to it combined malleability and melting characteristics. That's why industry has been having such a hard time getting away from using it. Try to make a decent ammunition bullet without it, not been done yet.
My favorite elements are Krypton, Iodine, Sulfur, Titanium, and Sodium.
All of which spells my name.
Carbon is nice too, me being Carbon-based and all...
I adore all the first group elements for their flame test colors, their shininess in pure form, and their general incongruity in science and technology. But if I had to pick something other than those, it would be Manganese for its name.
There is a bit of story behind Osmium being my favorite.
Upon joining the Chemistry Fraternity AXE as a grad student at UT Austin, we got to pick an element as our Frat nickname. As an Organic Chemist, most of the obvious choices were taken so I perused the available options. I noted the Os was still open and quickly realized that I could lay claim to being the Most Great and Powerful Os (making a spin off the movie the Wizard of Oz). It has been a source of much amusement over the years. I already have this element pin and wear it to select chemistry functions and end up telling the story often.
Secondly, I would pick Bromine due to many years spent doing research in support of my company's flame retardants business. I also have a Br element pin and wear it similarly as noted above.
My favorite element is boron. Boron has some metallic and some non-metallic properties. I also wrote my dissertation on boron-nitrogen chemistry...
Wayne L. Cook
Nuclear chemistry fascinates me, so I have to say plutonium. Besides being infamous for its role in nuclear weapons (like the bomb dropped on Nagasaki in 1945, which used plutonium-239), it also has some strange properties. For example, it shrinks as it gets hotter and conducts less heat or electricity than any other metal. I also find radium very interesting because of the history behind it. Marie and Pierre Curie first isolated it from uranium-laced ore in 1898, completely unaware of the negative health effects of the gamma rays and beta particles they were being exposed to. High doses of radium were even used in several medical procedures during the first half of the 20th century.
Boron is surprisingly necessary and interesting: in my bioinorganic class last year I chose to discuss boron's importance in plant cell walls as part of our end-of-semester presentation. This was because I love plants and because I didn't want to do the more obvious bioinorganic focus of metal-protein interactions. The experience is one of the few times I could make sense of biochemistry.
My favourite elements are Neodymium and Praseodymium used in the glassblower's didymium glasses and optical lenses in lasers.
These glasses are used by glassblowers since they effectively filter out the characteristic sodium yellow glow emitted when heating glass containing sodium making their work easier and unobscured in the flame. Didymium was once thought to be one element but later discovered to be two: Praseodymium and Neodymium. Together they strongly absorb the two sodium yellow emission lines with wavelengths close to 590 nm.
Here is a nice video done by Andrea Sella
I am surprised that I am the first to nominate silicon (Si) as a favorite element, one without which this discussion would not likely take place. But is has other attributes beyond semiconductors. In contrast to the opacity (visible light) of the pure crystalline material, the oxide is one of the most transparent: quartz. If you agree, reply "Si"