(a)[1]
State the meaning of isotopes.
(b(i))[2]
Using Fig. 2.1, calculate the relative atomic mass, $A_r$, of iron to one decimal place. Show your working.
(b(ii))[2]
Complete Table 2.1 so that it shows the number of protons and nucleons in one atom of $^{56}\text{Fe}$.
(c)[1]
Deduce how many pairs of electrons are present in the shell with principal quantum number $n = 3$ in an Fe atom.
(d)[1]
Write an equation that represents the first ionisation energy of iron.
(e)[4]
Suggest how the first ionisation energy of $^{54}\text{Fe}$ compares with the first ionisation energy of $^{56}\text{Fe}$. Explain your answer in terms of the factors that influence ionisation energy.