ðə ɹˈiːzənz fɚðə mˌɑːdɪfɪkˈeɪʃən bˌiːɪŋ hˈaɪli ɹɪˈæktɪv ænd ðɪ ɔːɹ mˌɑːdɪfɪkˈeɪʃənz bˌiːɪŋ tˈoʊɾəli ʌnɹɪˈæktɪv ɪz kˈɜːɹəntli ɐ mˈɪstɚɹi.
The reasons for the  modification being highly reactive and the  or  modifications being totally unreactive is currently a mystery.