diff --git a/README b/README
index 67d56454..29ae6b46 100644
--- a/README
+++ b/README
@@ -115,6 +115,9 @@ n-partition:
 ntp:
     simple NTP client
 
+periodic-words:
+    calculates if a word is "periodic", like "GeNiUS".
+
 picomath:
     implementation of picomath.org
 
diff --git a/periodic-words/periodic-words-tests.factor b/periodic-words/periodic-words-tests.factor
new file mode 100644
index 00000000..faa91d50
--- /dev/null
+++ b/periodic-words/periodic-words-tests.factor
@@ -0,0 +1,9 @@
+! Copyright (C) 2011 John Benediktsson
+! See http://factorcode.org/license.txt for BSD license
+
+USING: periodic-words tools.test ;
+
+IN: periodic-words
+
+[ t ] [ "Genius" periodic? ] unit-test
+[ f ] [ "Factor" periodic? ] unit-test
diff --git a/periodic-words/periodic-words.factor b/periodic-words/periodic-words.factor
new file mode 100644
index 00000000..5659d1b6
--- /dev/null
+++ b/periodic-words/periodic-words.factor
@@ -0,0 +1,152 @@
+! Copyright (C) 2011 John Benediktsson
+! See http://factorcode.org/license.txt for BSD license
+
+USING: ascii assocs combinators.short-circuit fry
+io.encodings.ascii io.files kernel math memoize sequences ;
+
+IN: periodic-words
+
+MEMO: elements ( -- assoc )
+    H{
+        { "H" "Hydrogen" }
+        { "He" "Helium" }
+        { "Li" "Lithium" }
+        { "Be" "Beryllium" }
+        { "B" "Boron" }
+        { "C" "Carbon" }
+        { "N" "Nitrogen" }
+        { "O" "Oxygen" }
+        { "F" "Fluorine" }
+        { "Ne" "Neon" }
+        { "Na" "Sodium" }
+        { "Mg" "Magnesium" }
+        { "Al" "Aluminium" }
+        { "Si" "Silicon" }
+        { "P" "Phosphorus" }
+        { "S" "Sulfur" }
+        { "Cl" "Chlorine" }
+        { "Ar" "Argon" }
+        { "K" "Potassium" }
+        { "Ca" "Calcium" }
+        { "Sc" "Scandium" }
+        { "Ti" "Titanium" }
+        { "V" "Vanadium" }
+        { "Cr" "Chromium" }
+        { "Mn" "Manganese" }
+        { "Fe" "Iron" }
+        { "Co" "Cobalt" }
+        { "Ni" "Nickel" }
+        { "Cu" "Copper" }
+        { "Zn" "Zinc" }
+        { "Ga" "Gallium" }
+        { "Ge" "Germanium" }
+        { "As" "Arsenic" }
+        { "Se" "Selenium" }
+        { "Br" "Bromine" }
+        { "Kr" "Krypton" }
+        { "Rb" "Rubidium" }
+        { "Sr" "Strontium" }
+        { "Y" "Yttrium" }
+        { "Zr" "Zirconium" }
+        { "Nb" "Niobium" }
+        { "Mo" "Molybdenum" }
+        { "Tc" "Technetium" }
+        { "Ru" "Ruthenium" }
+        { "Rh" "Rhodium" }
+        { "Pd" "Palladium" }
+        { "Ag" "Silver" }
+        { "Cd" "Cadmium" }
+        { "In" "Indium" }
+        { "Sn" "Tin" }
+        { "Sb" "Antimony" }
+        { "Te" "Tellurium" }
+        { "I" "Iodine" }
+        { "Xe" "Xenon" }
+        { "Cs" "Caesium" }
+        { "Ba" "Barium" }
+        { "La" "Lanthanum" }
+        { "Ce" "Cerium" }
+        { "Pr" "Praseodymium" }
+        { "Nd" "Neodymium" }
+        { "Pm" "Promethium" }
+        { "Sm" "Samarium" }
+        { "Eu" "Europium" }
+        { "Gd" "Gadolinium" }
+        { "Tb" "Terbium" }
+        { "Dy" "Dysprosium" }
+        { "Ho" "Holmium" }
+        { "Er" "Erbium" }
+        { "Tm" "Thulium" }
+        { "Yb" "Ytterbium" }
+        { "Lu" "Lutetium" }
+        { "Hf" "Hafnium" }
+        { "Ta" "Tantalum" }
+        { "W" "Tungsten" }
+        { "Re" "Rhenium" }
+        { "Os" "Osmium" }
+        { "Ir" "Iridium" }
+        { "Pt" "Platinum" }
+        { "Au" "Gold" }
+        { "Hg" "Mercury" }
+        { "Tl" "Thallium" }
+        { "Pb" "Lead" }
+        { "Bi" "Bismuth" }
+        { "Po" "Polonium" }
+        { "At" "Astatine" }
+        { "Rn" "Radon" }
+        { "Fr" "Francium" }
+        { "Ra" "Radium" }
+        { "Ac" "Actinium" }
+        { "Th" "Thorium" }
+        { "Pa" "Protactinium" }
+        { "U" "Uranium" }
+        { "Np" "Neptunium" }
+        { "Pu" "Plutonium" }
+        { "Am" "Americium" }
+        { "Cm" "Curium" }
+        { "Bk" "Berkelium" }
+        { "Cf" "Californium" }
+        { "Es" "Einsteinium" }
+        { "Fm" "Fermium" }
+        { "Md" "Mendelevium" }
+        { "No" "Nobelium" }
+        { "Lr" "Lawrencium" }
+        { "Rf" "Rutherfordium" }
+        { "Db" "Dubnium" }
+        { "Sg" "Seaborgium" }
+        { "Bh" "Bohrium" }
+        { "Hs" "Hassium" }
+        { "Mt" "Meitnerium" }
+        { "Ds" "Darmstadtium" }
+        { "Rg" "Roentgenium" }
+        { "Cn" "Copernicium" }
+        { "Uut" "Ununtrium" }
+        { "Uuq" "Ununquadium" }
+        { "Uup" "Ununpentium" }
+        { "Uuh" "Ununhexium" }
+        { "Uus" "Ununseptium" }
+        { "Uuo" "Ununoctium" }
+    } [ [ >lower ] dip ] assoc-map ;
+
+: element? ( from to word -- ? )
+    2dup length > [ 3drop f ] [ subseq elements key? ] if ;
+
+: (periodic?) ( word from -- ? )
+    {
+        [ swap length = ]
+        [
+            { 1 2 3 } [
+                dupd + [ pick element? ] keep
+                '[ dup _ (periodic?) ] [ f ] if
+            ] with any? nip
+        ]
+    } 2|| ;
+
+: periodic? ( word -- ? )
+    >lower 0 (periodic?) ;
+
+MEMO: dict-words ( -- words )
+    "/usr/share/dict/words" ascii file-lines ;
+
+: periodic-words ( -- words )
+    dict-words [ periodic? ] filter ;