Lessons by Helen W

1. The Lyman series converges to 91.2 nm. Use $IE = hc/\lambda_{lim}$ to find the ionisation energy of hydrogen in kJ mol⁻¹.
2. Calculate the convergence limit wavenumber for the Balmer series and hence the ionisation energy, given $R_H = 1.097\times10^7\ \mathrm{m^{-1}}$.
3. Explain why lines crowd together at the series limit, and state how the limit gives the energy needed to detach the electron completely.
4. A sample's convergence limit is 45.6 nm. Identify the element and explain your reasoning from its ionisation energy.