Answer: a. atomic number = 27
b. mass number = 57
c. total number of electrons = 25
d. total number of s electrons = 8
e. total number of p electrons = 12
f. total number of d electrons = 5
Explanation: The given ion of an isotope has 13 electrons at n=3 and 2 electrons at n=4. Thus the electronic configuration is
[tex]1s^22s^22p^63s^23p^63d^54s^2[/tex]
Thus the total number of electrons is 25. But as the isotope has lost two electrons to bear a +2 charge, the number of protons must be 25+2 = 27.
a) Atomic number of the element is equal to the number of protons, thus atomic number is 27.
b) Mass number is the sum of number of protons and the number of neutrons. mass number is a whole number and thus mass number = 57.
c) Total number of electrons is [tex]1s^22s^22p^63s^23p^63d^54s^2[/tex]=25.
d) Total number of s electrons = [tex]1s^2+2s^2+3s^2+4s^2[/tex]= 8
e) Total number of p electrons= [tex]2p^6+3p^6[/tex]= 12
f) Total number of d electrons= [tex]3d^5[/tex]= 5
