# What is the joke that is shown in this picture?

There is supposedly a joke shown in this picture relating to periodic trends. Does anyone know what it is? And could they also explain where the elements on the eye exam came from?

• To me it's just a joke about how instead of random letters they're using random element symbols, probably inspired in part by the fact that several elements are represented by a single letter. I fail to see anything related to periodic trends. – Nicolau Saker Neto Nov 25 '13 at 23:27
• Not entirely random. The elements are arranged in the same order they are found in a periodic table, reading as you would normally. It merely represents scientists using the periodic table as an eye chart. – long Nov 26 '13 at 9:44
• I find it bizarre that Mg was dropped. I suspect the artist found this version of the periodic table aesthetically pleasing? – bobthechemist Nov 26 '13 at 12:48

As commented by @long, the elements shown are not completely randomised. The elements in all the rows, except in the 3rd row ($\ce{Na, K, Ca}$), are arranged in same order as they are given in periodic table.
After studying them on periodic table for 15 minutes, it seemed to have no meaning. There are no periodic trends. $\ce{H, Li, Na, K, Rb}$ belongs to IA group, $\ce{Be, Ca, Sr}$ belongs to IIA group. And they are arranged in a random way, having no meaning.