Extension of the periodic table beyond the seventh period Reference Libraries
Actinium is a radioactive chemical element. The symbol for Actinium is Ac and the atomic number is 89. Actinium was discovered in 1899 by French chemist AndrÃ©-Louis Debierne. It was the first non-primordial radioactive element to be isolated. Actinium is amongst a group of 15 similar elements within the periodic table that make up the actinoid series. This substance was also independently...
- Like a worm in form or movement; vermiform; tortuous or sinuous; also, writhing or wriggling.
- Like the track or trace of a worm; appearing as if worm-eaten; vermiculate.
- Marked with fine, close-set, wavy or tortuous lines of color; vermiculated.
- A form of rusticated masonry which is so wrought as to appear thickly indented with worm-tracks.