How many electrons are in this?

40 2+


Is it 42?

2 Answers

  • 1 decade ago
    Favorite Answer

    Ca has atomic number 20 meaning it has 20 protons, and when it is neutral, 20 electrons. Since positive charge means more protons, that means a 2+ charge says the atom has 2 more protons than electrons. Since the number of protons didn't change, it had to lose 2 of those 20 electrons leaving it with 18 electrons.

  • Taylor
    Lv 4
    1 decade ago

    19 electrons

    19 protons

    39K, 40K, and 41K have 20, 21, and 22 neutrons, respectively.

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