Gizmo: “Electron Configuration” Date ____________
Activity C:
The diagonal rule
Get the Gizmo ready:
• On the PERIODIC TABLE tab, select Ar (argon).
• Select the ELECTRON CONFIGURATION tab.
• Turn on Show number of electrons.
Introduction: Beyond argon, it is a bit tricky to determine which subshell gets filled next. There
are several rules that scientists use to determine the electron configurations of larger atoms.
Question: How are the electron configurations of elements beyond argon determined?
1. Arrange: Create the correct electron configuration for argon. Then, click Next element to get
to potassium (K). Click once in the first 3d orbital, and then click Check.
What feedback is given? _____________________________________________________
2. Rearrange: As it happens, the 4s subshell is a lower-energy subshell than 3d, so it is filled
first. Remove the electron from the 3d orbital and place it in the 4s orbital. Click Check.
(Note: For simplicity, all but the outer shell electrons will disappear on the Bohr Model.)
Is this configuration correct? _____ What is the configuration? ___________________
3. Arrange: Click Next element and add an electron for calcium. Click Check.
What is the electron configuration for calcium? ____________________________________
4. Arrange: Click Next element and add an electron for scandium. Try different orbitals until
you find the right one.
What is the electron configuration for scandium? __________________________________
5. Observe: Scandium is the first element to contain electrons in the d subshell. How many
orbitals does the d subshell have, and how many electrons can fit in the d subshell?
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6. Infer: Select the PERIODIC TABLE tab. The middle section of the table is a chemical family
called the transition metals. Why do you think this section is ten columns wide?
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