The spelling of the word "Atlantion" is determined by its phonetic makeup. This word is comprised of four syllables, and each syllable has a specific phonetic sound. Using the International Phonetic Alphabet (IPA), we can transcribe its pronunciation as /ətˈlæn.ʃən/. The first syllable "at" is pronounced with the schwa sound /ə/. The second syllable "lan" has the long "a" sound /eɪ/. The third syllable "ti" is pronounced with the short "i" sound /ɪ/, and the final syllable "on" ends with the sh sound /ʃən/. When put together, the spelling of "Atlantion" becomes clear.