for 39K, does it have 19 protons/neutrons, 20 electrons, an atoic number of 39 and a mass number of 58? Is that correct?

1 Answer

  • 2 years ago

    ALL atoms of K, regardless of isotope have 19 protons. That is the atomic number of K, and the atomic number is always the number of protons in the nucleus. A neutral K atom will always have 19 electrons, one for each proton in the nucleus. The "39" is the mass number of the atom, which is the sum of protons and neutrons. So 39-19 = 20 is the number of neutrons in the nucleus.

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