Question

DETERMINE THE NUMBER OF PROTONS, NEUTRONS AND ELECTRONS IN EACH OF THE FOLLOWING SPECIES:
a) 21Sc45; b) 12Mg24; c) 40Zr91; d) 13Al27 (3+); e) 30Zn65 (2+)

Answer 1

The atomic number of the element equals the number of protons. Calculating the number of neutrons then becomes atomic mass of the isotope minus the atomic number of the element equals the number of neutrons. For uranium-235, atomic number 92, the number of neutrons is 235-92=143, or 143 neutrons.