The lightest, or least dense metal is a pure element called lithium. To refresh your memory, a pure element is "a substance whose atoms all (or in practice almost all) have the same atomic number, or number of protons," according to the dictionary. Lithium is nearly half as dense as water. In fact, if lithium weren't so reactive, a chunk of it could float on water.
There are, however, two other metals that are also less dense than water. They are potassium and sodium. I love science but I'm certainly not a "whiz kid" when it comes to understanding all of it. So I was surprised to learn that potassium and sodium were metals. Now in all fairness to my teachers, I probably did learn that back in school but I have long since forgotten it. While lithium, potassium, and sodium are light enough to float on water, they are so reactive that when they are placed on water they either burn or explode! And FYI, all other metals on the periodic table are all denser than water.
Hydrogen, however, is the lightest of them all. That is because because it consists simply of a single proton and sometimes a neutron (deuterium). Under certain conditions, it forms a solid metal. "This makes hydrogen the least dense metal, but it isn't generally considered a contender for "lightest" because it doesn't exist as a metal naturally on Earth." Again, I don't remember learning this, but somewhere along the line I must have.
Elemental metals can be lighter than water but they aren't always lighter than some metal alloys. The lightest metal alloy is a "lattice of nickel phosphorous tubes (Microlattice) that was developed by researchers at the University of California Irvine." This metallic micro-lattice is 100 times lighter than a piece of Styrofoam! Even though the alloy consists of metals that possess ordinary density (nickel and phosphorus), the material is extremely light. This is because the alloy is arranged in a cellular structure, consisting of 99.9% open air space. Although the structure is mostly open space, it's very strong because of how it can distribute weight. It can be helpful to compare this lightweight metal alloy to a human bone. Bones are strong because they are mainly hollow, not solid.
Like I say, I love science and i want to thank you for hangin' in there with today's blog. Sometimes I just have to share things!
As we enter into the holiday season with lots of shopping to be done, tomorrow's blog is on that very subject. I hope you'll plan on "hopping" by. Until then, it's Irwin Quagmire Wart signing off until tomorrow and wishing you much