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IT'S ELEMENTAL!
POTASSIUM SUSAN R. MORRISSEY, C&EN WASHINGTON
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HAT DO YOU T H I N K O F but I hadn't ever really thought about which when you look at element one element was my favorite. number 19 on the periodAfter some quick thinking, I recall blurtic table? As a chemist, I ing out tin because I was working with suppose my head should organotin halide compounds that summer be filled with images of chemically related in the lab. I then became curious to know things involving potassium, such as zeolite ifhe had a favorite element. As it turns out, structures being charge-balanced by K+, he did: potassium. but instead I think of what has to be one Why potassium, you might ask—well of the all-time great pickup lines. at least I did. It turns out that it's not beI was doing chemical research at my col- cause ofthe alkali metal's ability to regulate lege during the summer break and decided water balance in the body or its use in fireto attend a gathering at a friend's apart- works, but simply because he liked bament. It was a small school, so there weren't nanas, which—as we all know—are full of many students around—just scipotassium. ence enthusiasts like myself, I could appreciate his affecthose taking summer classes, and tion for bananas—after all, they a handful of others there for rantaste great and are good for you. dom reasons—but I hoped a lot In fact, potassium is an elecof people would show up. trolyte mineral essential to mainAs the night got under way I taining good health. Among its noticed a not-so-bad-looking guy many roles, potassium regulates whom I'd seen around campus. CELEBRATING cellular acid-base andfluidbalC&EN'S Before long, I found myself face ance, blood pressure, and neu80TH to face with him. He struck up a romuscular function. ANNIVERSARY conversation that included the Potassium deficiency is rare standard question about why I in people who eat a balanced diwas on campus and not spending the sum- et because adequate levels of the mineral mer relaxing by a pool somewhere, which are found in a variety of foods. For examis where he'd be if he didn't have to retake ple, meats, poultry andfishare high in K, a class he'd failed the past semester. as are bananas, potatoes, milk, and orange I explained that I was a chemistry ma- juice. Carrots, grapefruit, and onions all jor and was taking advantage of a wonder- contain moderate levels of K, while foods ful opportunity to do summer research. such as blueberries, cucumbers, and iceNow, usually guys aren't all that interested berg lettuce all have low K levels. in chemistry and just find another topic to But I digress. There is no doubt that talk about, but not this one. Instead, he potassium is important to good health, but replied, "So, what's your favorite element?" the question that night was This would not have struck me as weird whether it was good for the if we had both been science majors, health of my social life. As but I knew enough about him to our conversation continmake me wonder if he had ued, I began to wonder ever taken a chemistry if I had misjudged this class. %u can imagguy's chemical intellect. ine my shock and inPerhaps I should have trigue when I heard given him more credit, I the question. I was thought. speechless. I had an My doubt was short affinity for a numlived. One of the things that ber of elements, I found odd when Ifirstlearned about potassium was its chemical symbol, so I thought I would see if he GOING APE felt the same way But when I asked him Bananas provide a if he also found it odd that potassium's great source of potassium—a key symbol was K, he blew his wise chemical mineral for good health. facade. 64
C&EN / SEPTEMBER 8. 2003
"K?" he responded, asserting that the symbol was without a doubt P Needless to say, we spent a good bit of time arguing whether K or P was the correct symbol. He just wasn't buying that the K came from potassium's Latin name, kalium, or that I was a chemistry major who knew my elements. I even went as far as looking through my friend's apartment for a book POTASSIUM AT A GLANCE Name: From the English potash. The symbot.for potassium comes from the Latin kalium, alkali. Atomic mass: 39.10. History: Isolated in 1807 by Sir Humphry Davy. Occurrence: The seventh most abundant metal, but it is never found free in nature. Potassium is an essential constituent for plant growth and is found in most soils. It occurs in many minerals mined in Germany, Spain, Canada, the U.S., and Italy. Appearance: Soft, silvery metal. Behavior: One of the most reactive and electropositive metals. Apart from lithium, it is the least dense metal known. Potassium oxidizes very rapidly in air and must be stored under argon or under a suitable mineral oil. It reacts with water to form potassium hydroxide, hydrogen gas, and heat, and the heat usually ignites the hydrogen. Potassium and its salts impart a lilac color to flames. Uses: The metal is rarely used, but its compounds are important components of fertilizers, match heads, glass, soaps, and detergents. The potassium40 isotope is used to date rocks.
that had a periodic table in it, but unfortunately she didn't have any science books around. Days later, I caught up with him at the library and was able to show him a copy of the periodic table, thus proving K was really the correct symbol. Looking back, my excitement over talking chemistry at a college outing was a bit nerdy, but this guy didn't seem to mind. Although things didn't pan out between us, we had chemistry working for us for at least one evening. I just hope that he still remembers the correct symbol for potassium as well as I remember his pickup line. Susan R. Morrissey received her Ph.D. in chemistry from TexasA &M University. She is an associate editor covering government andpolicy issues for C&EN. HTTP://WWW.CEN-ONUNE.ORG
