Great fun, much harder than I thought it'd be... got 3 or 4 in the last minute, in the end I only missed Caesium, but my excuse is that it's called Cesium in the 'Periodic Table Quiz' on JetPunk ;)
We agree with Quizzer6794, and here's our reason why: All elements without a formal name are given a temporary systemic element name, derived from its atomic number, so for example theorised element 154 is called unpentquadium, effectively 154ium. You can try your luck naming them yourself at the Names of Unnamed Elements quiz.