ðə sˈɪnθəsˌɪs ʌv ʌnˌʌnɛnˈɪəm wʌz fˈɜːst ɐtˈɛmptᵻd ɪn nˈaɪntiːnhˈʌndɹɪd ˈeɪɾi fˈaɪv baɪ bəmbˈɑːɹdɪŋ ɐ tˈɑːɹɡɪt ʌv aɪnstˈaɪniəm tˈuːhˈʌndɹɪd fˈɪfti fˈoːɹ wɪð kˈælsiəm fˈoːɹɾi ˈeɪt ˈaɪɑːnz æt ðə sˈuːpɚ hˈɪlæk ɐksˈɛlɚɹˌeɪɾɚɹ æt ðə lˈɔːɹəns bˈɜːkli nˈæʃənəl lˈæbɹətˌɔːɹi ɪn bˈɜːkli, kˌælɪfˈoːɹniə.
The synthesis of ununennium was first attempted in 1985 by bombarding a target of einsteinium-254 with calcium-48 ions at the superHILAC accelerator at the Lawrence Berkeley National Laboratory in Berkeley, California.