Easy Symbols Across 2. This element's chemical symbol is He. 3. This element's chemical symbol is N. 6. This element's chemical symbol is C. 9. This element's chemical symbol is I. 10. This element's chemical symbol is U. Down 1. This element's chemical symbol is Li. 4. This element's chemical symbol is Ne. 5. This element's chemical symbol is Al. 7. This element's chemical symbol is Ar. 8. This element's chemical symbol is O.