Table 1 lists the first-ionization energies for the Period 3 elements (Na through Ar)…
CHEMISTRY · Multi-part · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
Table 1 lists the first-ionization energies for the Period 3 elements (Na through Ar) measured in kJ·mol⁻¹.
Table 1. First-ionization energy, Period 3
Na 496 Mg 738 Al 577 Si 786 P 1 012 S 996 Cl 1 251 Ar 1 526
The periodic trend in metallic and non-metallic behavior within Period 3 is often rationalized using these data.
Answer the following questions about the information in Table 1 and the chemical behavior of the Period 3 elements.
(a) Describe the overall trend in first-ionization energy across Period 3 and account for the two significant deviations from the trend that appear in Table 1.
(b) Relate the trend in first-ionization energy to the change in metallic versus non-metallic character across the period. In your answer, connect your reasoning to effective nuclear charge and shielding.
(c) The oxides of the Period 3 elements vary in acid–base behavior when dissolved in water. Explain how the trend in first-ionization energy helps to account for the observation that Na₂O reacts vigorously with water to give a strongly basic solution whereas SO₃ reacts to give an acidic solution.