The word lanthanides is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 17
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (38 words)
alanine, aliased, andante, anneals, annelid, dahlias, delints, denials, dentals, dentils, dentins, destain, details, detains, dilates, elastin, entails, halides, halites, handles, handset, indents, inhaled, inhales, inlands, instead, intends, lindens, linnets, nailset, sainted, salient, sealant, shinned, slanted, snailed, stained, thinned