If you have 58.93g of Co it means that you only have 1 mol (use a periodic table to find the answer, if you had more find it by proportion, it's easier).
There's 6.022 x 10^23 atoms per mol so you have 6.022 x 10^23 atoms of Co.
(once again if you had more mol, you could find the answer by proportions).
Mass number is equal to the number of protons plus the number of neutrons in a nucleus of an atom
Find your element on the periodic table. Locate the element’s atomic number.
Determine the number of electrons. Look for the atomic mass of the element. Subtract (-) the atomic number from the atomic mass
