Most symbols for elements on the periodic table are easy to learn, such as those for carbon, oxygen, and nitrogen: C, O, and N. There are eleven “oddballs,” though, because their symbols originated in other languages (Latin, mostly), and do not match their English names. Here’s a list of them, by atomic number, with an explanation for each.
11. Na stands for sodium because this element used to be called natrium.
19. K stands for potassium, for this element’s name used to be kalium.
26. Fe stands for iron because this element was formerly named ferrum.
29. Cu stands for copper because it used to be called cuprum.
47. Ag’s (silver’s) old name was argentum.
50. Sn’s (tin’s) name used to be stannum.
51. Antimony’s symbol, Sb, came from its former name, stibium.
74. Tungsten, with the symbol W, was once called wolfram. In some parts of the world, it still goes by that name, in fact.
79. Gold (Au) was called aurum in past centuries.
80. Mercury’s (Hg’s) old name is impossible (for me, anyway) to say five times, quickly: hydrargyrum.
82. Lead (Pb) was once called plumbum because plumbers used it to weight the lower end of plumb-lines.
I think learning things is easier, with longer retention, if one knows the reasons behind the facts, rather than simply attempting rote memorization.