Complex sentence: The melting and boiling points of ununseptium are not known; earlier papers predicted about 350--500 ° C and 550 ° C respectively, or 350--550 ° C and 610 ° C respectively.
Split into simpler sentences: The melting and boiling points of ununseptium are not known. Earlier papers predicted them to be about 350--500 ° C and 550 ° C respectively, or 350--550 ° C and 610 ° C respectively.