This lesson helps a student to deduce electronic configurations. It also includes the configurations of ions, including s2 ions such as Pb2+. Ionic configurations are less complex than atomic ones, and are more closely related to chemistry. There is no attempt to figure out the configurations of lanthanides or actinides, which are quite idiosyncratic.
The judging algorithm can recognize a correct configuration if the core is written out in full or if it is abbreviated, as for example [Ar]. The orbitals can be in any order, as long as the core comes first. If, in a quiz, a student gives a reasonable but incorrect configuration, such as [Ar] 4s2 3d4 for chromium, the answer is credited, but the student is shown the actual configuration ([Ar] 3d5 4s). The lesson contains many of the animations found in SIR Orbital and SIR Atomic, and may be used to reinforce and extend concepts presented in class using these Simulations and Interactive Resources.
Chapter 1 starts by animating the contrasting behaviour of classical (planet) and
quantum (electron) objects. Successive positions of an electron are not correlated, but we
can keep track of all of the locations, and build up a probability distribution of that
electron. The "orbital" is introduced as such a record. The idea of attractive
energy, zero at large distances, is illustrated by animations.
In Chapter 2 the hydrogen-like orbitals are introduced. The quantum numbers n, l and m are introduced and related to size, energy, symmetry, multiplicity and the letters s, p, d, f... Comprehension is tested for each by an exhaustive quiz.
In Chapter 3 the multi-electron orbitals are related to the hydrogen-like orbitals, showing how the multi-electron shell sequence 1, 4, 4, 9, 9, 16…arise Shells and valence electrons are noted. There is a big "find-the-orbital" quiz.
In Chapter 4 the student builds atoms, using the minimum-energy and Pauli principles. The facility shown allows electrons to be put anywhere. Elements from lithium to argon are so constructed.
The configuration notation is introduced, and the elements from Li to Cl then appear in a quiz of a type which will be used henceforth: to write the configuration in the conventional notation (e.g. [He] 2s2 2p). Configurations are correlated with chemical properties for the representative elements. Chapter 4 concludes with a comprehensive quiz in which the student is asked for the configurations of ten atoms. An informal score is kept.
Chapter 5 deals with ionic configurations. They are shown to be generally simpler and more predictable than those of atoms. The student deduces configurations of noble gas, d10, dn (transition), f14d10 and d10s2 (Sn2+, Tl+, Bi3+) ions. This chapter also ends with a quiz of ten ions; an informal score is kept.
Chapter 6 concludes the lesson with a quiz in which ten configurations of suitably varied atomic and ionic types are requested. A score is given, and may be entered in a dataset. The last screens allow the student to see the best scores (up to 15) and a histogram of the scores to date.
Home page | Index of lessons | Next lesson (Oxidation Numbers) | Previous lesson (Periodic Table)
Updated July 24, 2000