A researcher measures the first-ionization energies of the elements with atomic…
CHEMISTRY · Multi-part · A Level · Chemistry · Periodicity and periodic trends · Periodicity and periodic trends
Problem
A researcher measures the first-ionization energies of the elements with atomic numbers 19 through 36 and plots the values against atomic number. The plot shows a repeating saw-tooth pattern with pronounced local maxima at atomic numbers 20 and 36 and a conspicuous local minimum at atomic number 31. One data point, labeled element Y, lies near a local maximum with a first-ionization energy of 1 521 kJ·mol⁻¹.
Respond to the following prompts about element Y.
(a) Based on the pattern described, identify both the period number and the group number of element Y.
(b) Write the full ground-state electron configuration of Y, using orbital-box or spectroscopic notation.
(c) Under extreme laboratory conditions Y forms a binary fluoride. Predict the empirical formula of this compound and account for the stoichiometry in terms of Y’s electron configuration.
(d) Explain why Y possesses a higher first-ionization energy than its immediate neighbor with atomic number 35, making explicit reference to effective nuclear charge and subshell structure.