How many neutrons in the #""^56Fe# isotope?

1 Answer
Sep 19, 2016

Answer:

#""^56Fe# has 30 neutrons.

Explanation:

How did I know this? Well, an iron atom has 26 protons, positively charged, massive nuclear particles. The number defines #Z#, the atomic number; #Z=1, H#; #Z=2, He#; #Z=3, Li#;...........#Z=26, Fe#.............

The nucleus also contains neutrons, massive, neutrally charged particles, and to a first approximation, the sum of protons and neutrons gives tha mass of the isotope. So if the question mentions iron, I know that #Z=26#; it is thus simple to specify the isotopic mass if the number of neutrons is given.