Which of the following is the composition of an isotope of calcium (atomic number 20)?

22 protons, 20 neutrons, 19 electrons

19 protons, 20 neutrons, 19 electrons

20 protons, 25 neutrons, 20 electrons

21 protons, 20 neutrons, 20 electrons

1 Answer

  • Lexi R
    Lv 7
    7 years ago
    Favorite Answer

    the atomic number of an atom defines what element the atom is.

    It is the number of protons on the nucleus of the atom.

    The atomic number of Ca is 20, therefore it has 20 protons. Any atom that has 20 protons will always be a Ca atom.

    so the answer is

    20 protons, 25 neurons, 20 electrons

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