All alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in their having very similar characteristic properties.
ˈɔːl ˈælkəlˌaɪ mˈɛɾəlz hæv ðɛɹ ˈaʊɾɚmˌoʊst ᵻlˈɛktɹɑːn ɪn ɐn ˈɛsˈɔːɹbɪɾəl: ðɪs ʃˈɛɹd ᵻlˈɛktɹɑːn kənfˌɪɡjɚɹˈeɪʃən ɹɪzˈʌlts ɪn ðɛɹ hˌævɪŋ vˈɛɹi sˈɪmɪlɚ kˌæɹɪktɚɹˈɪstɪk pɹˈɑːpɚɾiz.