Although francium is the heaviest alkali metal that has been discovered, there has been some theoretical work predicting the physical and chemical characteristics of hypothetical heavier alkali metals.
ɔːlðˈoʊ fɹˈænsiəm ɪz ðə hˈɛviɪst ˈælkəlˌaɪ mˈɛɾəl ðɐthɐzbˌɪn dɪskˈʌvɚd, ðɛɹ hˈæzbiːn sˌʌm θiəɹˈɛɾɪkəl wˈɜːk pɹɪdˈɪktɪŋ ðə fˈɪzɪkəl ænd kˈɛmɪkəl kˌæɹɪktɚɹˈɪstɪks ʌv hˌaɪpəθˈɛɾɪkəl hˈɛviɚɹ ˈælkəlˌaɪ mˈɛɾəlz.