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10 October, 22:10

If the number of electrons in an atom is 39 and the mass number for the same atom is 90, calculate the the following for this atom: a) the number of protons b) the atomic number c) the number of neutrons d) What is the identity of this element?

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  1. 10 October, 23:32
    no. of protons = 39

    atomic number = number of protons = 39

    number of neutrons = 51

    element is Yttrium


    given dа ta:

    number of electron is 39

    mass of atom is 90

    We know that atoms are neutral because + ve charged protons is equal to no of - ve charged electrons.

    we know that:

    atomic number is equal to number of protons,

    and atomic mass is the summation of no. of protons and no. of neutrons

    number of protons = number of electrons

    from the data given:

    a) No. of protons = 39 (since number of electrons = protons)

    b) atomic number = number of protons = 39

    c) number of neutrons = atomic mass - atomic number

    = 90 - 39

    = 51

    d) element is Yttrium
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