The atoms in a sample of an element must contain nuclei with the same number of what?

1 Answer
anor277
Jun 10, 2017

With the same number of #"protons"#...........

Explanation:

The atoms in a sample of a given element all have the same #"atomic number"#, #Z#, which represents the number of #"protons"#, massive, positively charged nuclear particles. And #Z# determines the identity of the element: #Z=1, "hydrogen"#; #Z=2, "helium"#; #Z=6, "carbon"#; .......#Z=92, "uranium"#.

The nucleus CAN contain different numbers of #"neutrons"#, and this gives rise to the existence of isotopes. Isotopes are nuclides of the same element (and thus common #Z#), with different numbers of neutrons. Most elements have a number of specific isotopes. The weighted average of their mass is the atomic mass printed on the Periodic Table.

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