Successive Ionization Energies and Element Identification

Q16. Consider the following plot of successive ionization energies for an element in the third period of the Periodic Table of Elements. What is the identity of this element?

Background

Topic: Periodic Trends & Ionization Energy

This question tests your understanding of how ionization energies change as electrons are removed from an atom, and how these changes relate to the electron configuration and position of the element in the periodic table.

Key Terms and Concepts:

• Ionization Energy: The energy required to remove an electron from an atom or ion in its gaseous state.

• Successive Ionization Energies: The energies needed to remove each electron one after another from the same atom.

• Electron Configuration: The arrangement of electrons in an atom's orbitals.

• Period 3 Elements: Elements in the third row of the periodic table (Na, Mg, Al, Si, P, S, Cl, Ar).

Step-by-Step Guidance

1. Examine the plot: Notice the gradual increase in ionization energy for the first 8 electrons, followed by a very large jump for the 9th electron.

2. Recall that a large jump in ionization energy typically occurs when removing an electron from a new, lower-energy shell (core electrons), after all valence electrons have been removed.

3. Count the number of electrons removed before the big jump: In this plot, the jump occurs after the 8th electron is removed, suggesting the element has 8 valence electrons.

4. Identify which Period 3 element has 8 valence electrons. Consider the electron configurations for each element in Period 3.

Try solving on your own before revealing the answer!