Question

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

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? ____

1. rearrange: 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? __

1. arrange: click next element and add an electron for calcium. click check

what is the electron configuration for calcium? ____

1. arrange: click next element and add an electron for scandium. try different orbitals until you find the right one. what is the configuration for scandium? ____
2. 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? ____
3. infer: select the periodic table tab. the middle section of the table contains ten groups that make up the transition metals. why do you think this section is ten columns wide? ____
4. observe: select the electron configuration tab. make sure the subshells are ordered by energy, which will arrange them from lowest to highest energy, bottom to top

based on what you see, in what order do you think subshells will be filled? ____

Explanation:

Step1: Argon to Potassium Feedback

When an electron is placed in the 3d - orbital for potassium instead of 4s - orbital first, the feedback is likely that the electron configuration is incorrect because the 4s sub - shell has lower energy and should be filled first according to the Aufbau principle.

Step2: Potassium Correct Configuration

Yes, the configuration is correct when the electron is in the 4s orbital. The electron configuration for potassium is [Ar]4s¹.

Step3: Calcium Electron Configuration

Calcium has 20 electrons. After argon (18 electrons), the next two electrons go into the 4s orbital. So the electron configuration is [Ar]4s².

Step4: Scandium Electron Configuration

Scandium has 21 electrons. After the [Ar] core and 4s² configuration, the next electron goes into the 3d orbital. So the electron configuration is [Ar]4s²3d¹.

Step5: d - Subshell Properties

The d sub - shell has 5 orbitals. According to the Pauli exclusion principle, each orbital can hold a maximum of 2 electrons. So the d sub - shell can hold a maximum of 10 electrons.

Step6: Transition Metal Columns

The middle section of the periodic table is ten columns wide because the d sub - shell, which is being filled in the transition metals, has 5 orbitals and each orbital can hold 2 electrons, giving a total of 10 possible electrons to be added across these ten groups as the d sub - shell is filled.

Step7: Subshell Filling Order

The subshells are filled in the order 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p based on the increasing energy of the subshells (the Aufbau principle).

Answer:

1. The feedback is that the electron configuration is incorrect as 4s should be filled before 3d.
2. Yes; [Ar]4s¹
3. [Ar]4s²
4. [Ar]4s²3d¹
5. 5 orbitals; 10 electrons
6. Because the d - subshell being filled in transition metals has 5 orbitals and each orbital can hold 2 electrons.
7. 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p