Atoms in solids

The first lesson shows that all matter consists of atoms. It will take students inside graphite and a diamond. Students will see that both materials consist of the same carbon atoms, but have very different properties because their atomic level structure is different. Students will also learn that atoms in solids do not stay still – they vibrate.

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

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Transcript

Wel­come to the MEL Vir­tu­al Lab­o­ra­to­ry, where you can see the in­vis­i­ble.

To­day you will use our vir­tu­al mi­cro­scope for the first time.

We will start with a di­a­mond.

This di­a­mond is called the Koh-i-Noor.

It was found in In­dia about a thou­sand years ago. Peo­ple es­ti­mate its val­ue to be over a bil­lion dol­lars.

Let's look in­side. Ready to dive?

We will zoom in. Each cell you see is ten times small­er than the one be­fore. We need to zoom in about a bil­lion times. That’s nine ze­ros af­ter a one!

And now we see these small par­ti­cles that our di­a­mond is built of. They're called atoms.

But in real life they do not stay still. They are vi­brat­ing.

Let's switch time on. Ready, steady, go…

All mat­ter is built of atoms that are con­stant­ly mov­ing. In solids, like our di­a­monds, they vi­brate.

You can see how each atom is con­nect­ed to four oth­ers. Such a strong struc­ture makes a di­a­mond one of the hard­est ma­te­ri­als.

Let's re­turn back to our lab­o­ra­to­ry.

We also have a pen­cil here. It's a bil­lion times cheap­er, but in­ter­est­ing­ly its lead is made of the same car­bon atoms as a di­a­mond.

Let's look in­side. Ready to dive?

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

They are the same car­bon atoms as in a di­a­mond but their ar­range­ment is dif­fer­ent. As you can see, they are laid out in lay­ers. These lay­ers are easy to sep­a­rate from each oth­er, since there is no strong bond be­tween them.

This makes graphite much soft­er than a di­a­mond. When you write with your pen­cil, the marks on the pa­per are traces of the graphite.

You can fly in­side this graphite crys­tal and ex­plore it by your­self.

Just to re­mind you, you are now as small as an atom and what you see around you is the tip of a pen­cil en­larged a bil­lion times.

Let's go back to our lab­o­ra­to­ry.

You have seen that both di­a­mond and graphite are built of the same atoms but they have very dif­fer­ent prop­er­ties be­cause of their atom­ic struc­ture.

Try to re­call how small the atoms are. What do you think is big­ger, an atom or a bac­teri­um?

A bac­teri­um is much, much big­ger than an atom. Each bac­teri­um con­tains bil­lions of atoms.

Now, try to think how big an atom is?

An atom is about ten mil­lions times small­er than a mil­lime­ter.

If an atom were the size of an ant, then this ant would be the size of Man­hat­tan.

Teacher's notes

Key­words

atoms, mat­ter, state of mat­ter, solids, mat­ter prop­er­ties

Com­mon mis­con­cep­tions

  • Atoms in solids don't move.

Stu­dents will

  • Learn that mat­ter con­sists of atoms
  • Learn that atoms in solids are packed close to­geth­er and re­main in the same place
  • Find out that atoms in solids are con­stant­ly vi­brat­ing
  • See that dif­fer­ent ar­range­ments of the same type of atoms lead to dif­fer­ent prop­er­ties in solids
  • Com­pare the size of atoms to oth­er ob­jects

Hands-on ac­tiv­i­ties

Af­ter VR

The aim is to show the stu­dents that the struc­ture of graphite (seen in VR) is what al­lows pen­cils to write. As we write, lay­ers of graphite are me­chan­i­cal­ly peeled off the sur­face of the pen­cil core. As graphite is a con­duc­tor, we can see that a pen­cil line can con­nect an elec­tri­cal cir­cuit.

Ask stu­dents to con­nect an elec­tri­cal cir­cuit with a pen­cil line. The diode will light up. Let stu­dents try to ex­plain why this hap­pens.

His­to­ry and sources of knowl­edge

  • From an­cient Greeks to Dal­ton's the­o­ry and mod­ern days.
  • Mod­ern tech­niques to see atoms: scan­ning tun­nel­ing mi­cro­scope – im­age of a sin­gle-wall car­bon nan­otube: image.

Top­ics to dis­cuss

  • How can we trust the­o­ries about things we can't see?
  • The best sci­en­tif­ic ex­pla­na­tion is based on ev­i­dence (ob­ser­va­tions) and sci­en­tif­ic knowl­edge.

Fun facts and quotes

  • How small atoms are: If atoms were the size of an ap­ple, an ap­ple would be big­ger than the Earth.
  • A cop­per pen­ny con­tains a tril­lion times (1,000,000,000,000) more atoms than there are peo­ple on the Earth (which is greater than 7 bil­lion).

From the lec­tures of No­bel Prize win­ner Richard Feyn­man:

“If, in some cat­a­clysm, all of the sci­en­tif­ic knowl­edge were to be de­stroyed and only one sen­tence passed on to the next gen­er­a­tions of crea­tures, what state­ment would con­tain the most in­for­ma­tion in the fewest words? I be­lieve it is the atom­ic hy­poth­e­sis (or the atom­ic fact, or what­ev­er you wish to call it) that all things are made of atoms—lit­tle par­ti­cles that move around in per­pet­u­al mo­tion, at­tract­ing each oth­er when they are a lit­tle dis­tance apart, but re­pelling upon be­ing squeezed into one an­oth­er.”

Ques­tions

  • Name some­thing around you that con­sists of atoms.
  • Name some­thing that doesn't con­sist of atoms.

Cal­cu­lat­ing

Count how long a line of 1,000,000 sul­fur atoms would be if ar­ranged side by side, if a sin­gle sul­fur atom is 200 pm (0.0000000002 m).

Quiz

Please see be­low for the link to a Google form con­tain­ing a quiz on the ma­te­ri­al above.

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/sh7L­H­n1g­p­s8g6Pid8