To celebrate 150 years of the periodic table, all the words in this grid are made from chemical element symbols. Fill each white square with one element. Take care! Some squares contain more than one letter, and some words can be made in more than one way: a clue asking for a seven-letter element could yield SiLiCON or SILiCoN, for example. The chemical formula below indicates how many of each element is needed to complete the entire grid. Tell us how you fared at crossword@newscientist.com
AcAl2AmAr3At2BiC7CaCo3CrEr5Es4Fe2GeH3HeI15InKLa2LiN8O8Os2P6RaRe3S12Ti4Ts2U4V3W2