The probable properties of further alkali metals beyond unsepttrium have not been explored yet as of 2019, and they may or may not be able to exist.
ðə pɹˈɑːbəbəl pɹˈɑːpɚɾiz ʌv fˈɜːðɚɹ ˈælkəlˌaɪ mˈɛɾəlz bᵻjˌɔnd ʌnsˈɛptɹiəm hɐvnˌɑːt bˌɪn ɛksplˈoːɹd jˈɛt æz ʌv tˈuː θˈaʊzənd nˈaɪntiːn, ænd ðeɪ mˈeɪ ɔːɹ mˈeɪ nˌɑːt biː ˈeɪbəl tʊ ɛɡzˈɪst.