Orbital names

Now that students know that electron behavior in atoms is described using orbitals, it is time to learn the orbitals' names. Students will see electrons added to an atom one by one and learn the names of the orbitals.

This lesson is a part of MEL Chemistry VR. Learn more →

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Transcript

Re­mem­ber you have seen elec­tron or­bitals that have dif­fer­ent shapes? To­day we will learn their names.

Let's take a piece of sul­fur and look in­side to see its atoms. Ready to dive?

We have to zoom in a bil­lion times to see in­di­vid­u­al sul­fur atoms.

Let's choose one of those atoms and get clos­er.

You see a lot of dif­fer­ent elec­tron or­bitals.

Let's re­move all the elec­trons and add them back one by one.

As you may re­mem­ber, the first elec­tron or­bital has a spher­i­cal shape. We call this or­bital S. In­deed, we call it 1s to show that it is the first spher­i­cal or­bital.

Two elec­trons can fit in one or­bital, so the sec­ond elec­tron will go to the same 1s or­bital.

The third elec­tron can­not be added to an or­bital that al­ready con­tains two elec­trons.

So, it will go to the next or­bital.

This spher­i­cal or­bital is called 2s. The next elec­tron will go there as well.

The next or­bital is called p or 2p, to in­di­cate it is lo­cat­ed in the sec­ond shell.

Now watch care­ful­ly what hap­pens with the next elec­tron. It will not go to the same or­bital but will rather go to an­oth­er p or­bital.

To dis­tin­guish be­tween these p or­bitals, we will call our first or­bital px and our new or­bital py. But why did not it go to the same or­bital as the pre­vi­ous elec­tron?

As you may re­mem­ber, elec­trons are at­tract­ed to the pos­i­tive­ly charged nu­cle­us. So, they want to be as close to the nu­cle­us as pos­si­ble.

But at the same time, neg­a­tive­ly charged elec­trons re­pel each oth­er. So, if there are two or­bitals the same dis­tance from the nu­cle­us, the elec­trons pre­fer to be in dif­fer­ent or­bitals, far­ther away from each oth­er.

Fol­low­ing this log­ic, the next elec­tron will go to the third p or­bital called pz. There are only three p or­bitals so the next elec­tron must share an or­bital. Let's con­tin­ue adding elec­trons.

Now all the 2p or­bitals are full; there is no space for any ad­di­tion­al elec­trons in them. There­fore the next elec­tron will go far­ther away from the nu­cle­us to the next spher­i­cal or­bitals.

Try to guess its name.

It is called 3s.

We will con­tin­ue adding elec­trons and show the names of the or­bitals.

Now when we have added 16 elec­trons our sul­fur atom is com­plete.

Let's go back to our lab­o­ra­to­ry.

Try to re­call the max­i­mum num­ber of elec­trons that can share the same or­bital?

Only two elec­trons can share the same or­bital. In the next lessons, you will learn the rea­sons for that.

Teacher's notes

Key­words

elec­trons, elec­tron shells, or­bitals, s-or­bital, px-, py-, pz-or­bitals

Stu­dents will

  • Re­call that elec­trons in atoms are on dif­fer­ent­ly-shaped or­bitals
  • Learn that one or­bital can fit two elec­trons
  • See in what or­der or­bitals are filled with elec­trons
  • Learn or­bital names

Hands-on ac­tiv­i­ties

Af­ter VR

The aim is to give stu­dents a “real life” anal­o­gy to the or­der in which elec­trons ap­pear.

Stu­dents are giv­en a “ho­tel ac­tiv­i­ty sheet” and are asked to al­lo­cate guests in the ho­tel ac­cord­ing to the rules.

Rules for guests:

  1. No more than 2 guests per room.
  2. The lift is bro­ken, and the guests are lazy: they will al­ways try to get a place in a room clos­est to the ground floor.
  3. Guests will try to avoid neigh­bors if it doesn't cause them to use the stair­case.

His­to­ry and sources of knowl­edge

  • Quan­tum the­o­ry: de­scrip­tion, com­pu­ta­tion­al mod­els.
  • Atom­ic spec­tra with shell se­ries. Zee­man and Stark ef­fects clear­ly show the num­ber of p-, d-, and f-or­bitals.

Top­ics to dis­cuss

  • How can we trust the­o­ries about things we can't see?
  • Quan­tum the­o­ry
  • Rules for elec­trons: Pauli Ex­clu­sion Prin­ci­ple, Auf­bau Prin­ci­ple, & Hund's Rule

Fun facts and quotes

Names of the or­bitals: s-, p-, d-, and f- can seem like a ran­dom set of let­ters. Ear­ly spec­tro­scopists who re­searched the se­ries in spec­tra of al­ka­li met­als could see dif­fer­ent sets of lines for each elec­tron shell. They cat­e­go­rized these lines as sharp, prin­ci­pal, dif­fuse, and fun­da­men­tal. The or­bitals were named af­ter the cor­re­spond­ing sets of lines.

Ques­tions

  • How many elec­trons can fit into one or­bital?
  • What is the elec­tron fit­ting or­der for a lithi­um atom?

Quiz

Please see be­low for the link to a Google form con­tain­ing a quiz on ma­te­ri­als from two lessons: Elec­tron Or­bitals and Or­bital Names.

This can be as­signed dur­ing class time or as home­work. The quizzes are marked and the sys­tem shows which ques­tions stu­dents get cor­rect and in­cor­rect. Please note that stu­dents should record their scores, as they will not be view­able lat­er.

https://forms.gle/h3XR2jtxb­HoBzSx­h6