I just saw this project advertised on a board on Ravelry and I am excited!

As 2011 is the International Year of Chemistry, the Knit The Periodic Table of the Elements project will collect squares from knitters, and have them sewn together to be displayed at the New Zealand Institute of Chemistry conference, and other places. 

I signed up to knit Thulium (Tm), because I had no opinion on the merit of any one element over any other element, Potassium (K) was taken (K is my initial), and the atomic number of Thulium is 69, which is a much finer number than any other.

Wikipedia tells me that

Thulium ( /ˈθjuːliəm/ thew-lee-əm) is a chemical element that has the symbol Tm and atomic number 69. Thulium is the second least abundant of the lanthanides (promethium is only found in trace quantities on Earth). It is an easily workable metal with a bright silvery-gray luster. Despite its high price and rarity, thulium is used as the radiation source in portable X-ray devices and in solid-state lasers.

also that Thulium is

Not to be confused with Thallium or Thorium.

 So now you know.

I will have to get moving on this square, as it has to be in NZ in a month's time.  It is only a 20cm stocking stitch square in 8ply, which won't take long, and a strip of black stocking stitch for the symbol.  I figure that making the symbol will take longer than making the square itself.  Watch this space.