Answer:
Fe is just the shortened version of Iron whereas Fe2+ is a positive ion,cation to be more specific
Answer:
Nitrogen
Explanation:
Nitrogen has 5 Valence Electrons.
And its atomic mass is also less than Bismuth.
There are other elements in the 5th row but this one has the lowest atomic mass compared to the others.
Atomic number, because the atomic number is unque to each individua element.