Tree view with drag-n-drop, RTL.
Metals
Alkaline Metals
Lithium (Li)
Sodium (Na)
Potassium (K)
Transition Metals
Scandium (Sc)
Titanium (Ti)
Vanadium (V)
Halogens
Fluorine (F)
Chlorine (Cl)
Bromine (Br)
Empty group