The rules above do not always apply to exotic atoms which contain short-lived elementary particles other than protons, neutrons and electrons.
ðə ɹˈuːlz əbˌʌv duːnˌɑːt ˈɔːlweɪz ɐplˈaɪ tʊ ɛɡzˈɑːɾɪk ˈæɾəmz wˌɪtʃ kəntˈeɪn ʃˈɔːɹtlˈɪvd ˌɛlɪmˈɛntɚɹi pˈɑːɹɾɪkəlz ˈʌðɚ ðɐn pɹˈoʊtɑːnz, nˈuːtɹɑːnz ænd ᵻlˈɛktɹɑːnz.