The Oddo–Harkins rule holds that elements with even atomic numbers are more common that those with odd atomic numbers, with the exception of hydrogen.
ðɪ ˈɑːdoʊ hˈɑːɹkɪnz ɹˈuːl hˈoʊldz ðæt ˈɛlɪmənts wɪð ˈiːvən ɐtˈɑːmɪk nˈʌmbɚz ɑːɹ mˈoːɹ kˈɑːmən ðæt ðoʊz wɪð ˈɑːd ɐtˈɑːmɪk nˈʌmbɚz, wɪððɪ ɛksˈɛpʃən ʌv hˈaɪdɹədʒən.