Final answer:
The atomic masses provided are for super-heavy elements, some of which are incorrect or hypothetical, such as Cobalt with a mass of 270, which is not accurate. Super-heavy elements have atomic numbers that define their chemical characteristics, and their mass numbers comprise the total number of protons plus neutrons.
Step-by-step explanation:
The given atomic masses are associated with super-heavy elements, some of which have yet to be discovered or may not exist naturally, and others are not correct for the elements listed (e.g., Cobalt (Co) does not have an atomic mass of 270). All known elements have a specific atomic number, which defines the element and its position on the periodic table, and this number corresponds to the number of protons in the nucleus. The mass number, on the other hand, is the sum of protons and neutrons in the nucleus. A few of the elements you've mentioned (Bohrium (Bh), Dubnium (Db), Hassium (Hs), and possibly Ununennium (Uue) if it were to be discovered) fit this category of super-heavy elements, typically found at the bottom of the periodic table and predominantly synthesized in laboratories.
The correct atomic masses for given elements as known per the information you've provided would be different: Hassium (Hs) at (277, 285), Meitnerium (Mt) at (276, 281, 282), Darmstadtium (Ds) at (268, 269, 270), Roentgenium (Rg), Copernicium (Cn) at (285), Flerovium (Fl) at (289), and Ununtrium (Uut) at (284).