The word tetroxides 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: 18
Highest Scoring Words With Friends™ Play In The Letters tetroxides
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Seven Letter Word Alert: (22 words)
detorts, detoxes, diester, dieters, distort, dittoes, dotiest, dotters, dottier, editors, erotise, existed, extorts, reedits, roisted, rosette, sortied, steroid, storied, testier, texters, tierods