气体中的原子

您将在氦气球内放大,并看到氦气由正在飞行的原子组成。您将看到,气体中的原子彼此之间的距离比固体中的原子更远。最后,您将看到如果提高温度,原子将如何开始更快地飞行。

本课程是MEL Chemistry VR的一部分。 Learn more →

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成绩单

In our pre-vi-ous les-son you saw that solids con-sist of small atoms that are vi-brat-ing. Now, what about?gas-es?

We have a he-li-um-filled bal-loon in our lab. Cer-tain-ly you've seen bal-loons like it at birth-day?par-ties.

Let's look in-side. Ready to?dive?

We have to zoom in a bil-lion times to see the in-di-vid-u-al?atoms.

You can see that he-li-um gas is made of small he-li-um atoms, but these atoms are much fur-ther apart than the ones we saw in a?di-a-mond.

In real life the atoms don't stay still. Re-mem-ber, in solids they vi-brate. Let's switch time on and see what hap-pens in a gas. Ready, steady, go …?.

They're?fly-ing!

This gas is at nor-mal room tem-per-a-ture, but what will hap-pen if we in-crease the?tem-per-a-ture?

Let's heat the gas to 1000?de-grees.

You see our atoms are fly-ing much faster. Ac-tu-al-ly, such ran-dom atom move-ment is what we call tem-per-a-ture. The faster atoms fly or vi-brate, the high-er the tem-per-a-ture will?be.

Take a few mo-ments and fly around?in-side.

You're now as small as an atom. The next time you're at a birth-day par-ty and you see a he-li-um bal-loon, you can tell your friends that you flew in-side the same kind of bal-loon and saw these tiny?atoms.

Re-mem-ber that, in the pre-vi-ous les-son, you saw that in solids the atoms are close to-geth-er. How-ev-er, in gas-es there is plen-ty of space be-tween atoms. That's why gas-es are much lighter than solids: There are far few-er atoms in the same?vol-ume.

Try to es-ti-mate how many more atoms of a sol-id are in the same space as com-pared to this?gas.

There are about a thou-sand times more atoms in the same space in solids com-pared to gas-es. That is why gas-es are, on av-er-age, about a thou-sand times lighter than?solids.

Let's go back to our?lab-o-ra-to-ry.

Now we have a tricky ques-tion for you. Are there things that do not con-sist of?atoms?

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Not ev-ery-thing con-sists of atoms. Light, for ex-am-ple, con-sists of pho-tons, which are dif-fer-ent kinds of par-ti-cles with dif-fer-ent?prop-er-ties.

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老师的笔记

Key-words

atoms, mat-ter, state of mat-ter, gas,?tem-per-a-ture

Com-mon?mis-con-cep-tions

  • Gas-es are not mat-ter be-cause we can't see them or feel their?mass.

Stu-dents?will

  • Learn that atoms in gas-es are much fur-ther away from each oth-er than in?solids
  • Find out that atoms in gas-es are fly-ing?freely
  • See that when the tem-per-a-ture in-creas-es atoms in gas start to move faster and when the tem-per-a-ture de-creas-es they slow?down
  • Be able to com-pare the den-si-ty of gaseous ob-jects to sol-id?ones

Hands-on?ac-tiv-i-ties

Be-fore?VR

The goal is to demon-strate how much denser liq-uid and sol-id ob-jects are com-pared to gas-es. Ask stu-dents to de-ter-mine (make mea-sure-ments with a set of weights and then count) how many he-li-um bal-loons a stu-dent needs to lift him/her up in the?air.

Equip-ment: bal-loons filled with he-li-um, set of?weights.

Af-ter?VR

Sy-ringe?ex-per-i-ment.

The goal is to show stu-dents how pow-er-ful gas par-ti-cle mo-tion is. Ask stu-dents to pull out a sy-ringe plunger and keep it in place with their fin-gers. Let them see how easy they can do it. Then ask them to close the hole with their fin-ger and pull out the plunger again. Let them feel that it be-comes much hard-er to hold the plunger so that they can see how rig-or-ous-ly gas par-ti-cles move and hit ev-ery-thing?around.

His-to-ry and sources of?knowl-edge

  • The an-cient Greek the-o-ry that air was one of the ba-sic?el-e-ments.
  • Dis-cov-ery of dif-fer-ent gas-es in the?air.
  • Our knowl-edge about air as a mix-ture of?gas-es.
  • Par-ti-cle mo-tion in gas-es: un-der a mi-cro-scope, we can see the Brown-ian mo-tion of tiny smoke par-ti-cles in the air. It proves that air con-sists of tiny par-ti-cles mov-ing?chaot-i-cal-ly.

Top-ics to?dis-cuss

  • How do we know that there are gas par-ti-cles around us if we can't see?them?
  • The speed of gas?par-ti-cles.
  • How much denser are solids than?gas-es?
  • Bil-lions of gas par-ti-cles are hit-ting us, why don't we feel?it?

有趣的事实和报价

  • If you stretch out the palm of your hand, you ac-tu-al-ly hold about 100 kg of?air.
  • The heav-i-est gas is sul-phur hex-aflu-o-ride. If you pour this gas in the tank 锡纸船将漂浮在其顶部.
  • Air is rough-ly 1,000 times less dense than wa-ter. 1 cu-bic me-ter of wa-ter weighs 1 ton or 1,000 kg, while 1 cu-bic me-ter of air weighs ap-prox-i-mate-ly 1.3?kg.

Ques-tions

  • Why can gas-es change their shape and solids?can't?
  • Why can gas-es change their vol-ume and solids?can't?
  • What is denser gas or sol-id and?why?

Cal-cu-lat-ing

In Chi-na, one of the world’s fastest trains can reach a speed of 430 km/h (ap-prox-i-mate-ly 0.2 km/s). In the air, oxy-gen par-ti-cles trav-el at around 500 m/s. Which is faster oxy-gen par-ti-cles or the?train?