[Answer] Most of an atom's mass is contained in the _______.

Answer: Nucleus

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Most of an atom's mass is contained in the _______. More than 99.94% of an atom's mass is in the nucleus. The protons have a positive electric charge the electrons have a negative electric charge and the neutrons have … The first scientists to determine relative atomic masses were John Dalton and Thomas Thomson between 1803 and 1805 and Jöns Jakob Berzelius between 1808 and 1826. Relative atomic mass (Atomic weight) was originally defined relative to that of the lightest element hydrogen which was taken as 1.00 and in the 1820s Prout's hypothesisstated that atomic masses of all elements would prove to be exact multiples of that of hydrogen. Berzelius however soon proved that this was not even approximately true and fo… Atomic mass - Wikipedia Much of an atom's positive charge is concentrated in a rel...

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