Like this? like this, or maybe one of these?

像這樣？這樣，或者這些其中之一？

If you understand enough about atoms to visualize any of those things,

如果你對於原子了解得夠多到足以能夠對它們在腦中以視覺方式呈現時

then you know more about atomic theory than a scientist did just a hundred years ago .

你就比一百年前的一個科學家還要了解原子理論

And like way more than they thought they knew 2500 years ago .

且是遠比他們在2500年前認為自己所知的要多出許多許多

That's when Greek philosopher Leucippus and his pupil Democritus

這是從希臘哲學家Leucippus和他的徒弟Democritus

first came up with the idea that matter is composed of tiny particles

首次想到物質是由微小粒子所組成的這個概念開始

No one knows how they developed this concept,

其實沒人知道他們怎麼想到這個概念的

but they didn't think that the particles were particularly special,

但他們並不覺得粒子是什麼特別的概念

they just thought that if you cut something in half enough times,

而只是想說如果把一個東西一直切成兩半、再兩半，如此一直下去，直到足夠的次數

eventually you'll reach a particle that can't be cut anymore.

最終你就會達到粒子等級的大小，而無法在分割下去

They gave these particles the name 'A Tomos'

他們給了這種粒子一個名字叫做 ''A Tomos''

which means uncuttable or indivisible

代表無法切割的或者無法分割的

So basically, they though that iron was made up of iron particles

所以基本上，他們認為鐵為鐵粒子組成的

and clay was made up of clay particles

而泥土是泥土粒子組成的

and cheese was made up of cheese particles.

而起司是由起司粒子組成的

And they attributed properties of each substance to the forms of the atoms.

而他們把物質的性質歸因於原子的組成形式而生

So they thought that iron atoms were hard and stuck together with hooks.

所以他們認為鐵原子也很堅硬且彼此有鉤子相連著

Clay atoms were softer and attached by a ball and socket joints that made them flexible.

泥土原子就是軟軟的且為球狀彼此黏附在一起並具有關節所以有彈性

And cheese atoms were squishy and delicious.

而起司原子就是軟綿綿的且很好吃

Now this makes a certain amount of sense if you don't happen to have access

你若不是正好可以使用電子顯微鏡或者是陰極射線管或者是

to electron microscopes or cathode ray tubes or the work of generations of previous scientists.

在學習過去幾個世代科學家的研究成果的話這樣子的說法聽起來還有幾分合理

Cause the fact is, atom theory, as we know it today, is the product of hundreds,

事實上，原子的理論，正如我們今日所知道的，如果沒有上千位

if not thousands of different insights.

也是由好幾百位科學家不同的洞見所集合而成的

Some models, like that of Leucippus were just blind guesses.

其中某些模型，像是Leucippus臆測的

As time went on, many more were the result of rigorous experimentation.

隨著時間演進，有更多的經過嚴格檢驗的實驗結果

But, as has been the case in all science,

但，作為一個所有科學中的例子

each scientist built on what had been learned before.

每位科學家都奠基在過去所學的基礎上

We've been talking a lot about the fine details of chemistry in recent weeks

我們在最近這幾週談論了許多關於化學的深入內容

and we're gonna keep doing that as we move on to nuclear chemistry,

並且我們要繼續往前探討至核子化學的部分

and then to the basics of organic chemistry.

之後會進入到有機化學的基礎課程中

But before we do, I wanted to set aside some time to explain how we know

但在我們開始之前，我想要花點時間解釋

what we know about the atom today,

我們了解原子的演進歷程

and how we know that we're not quite done figuring it out.

以及我們如何知道我們尚未完全了解它

♫Theme music♫

主題音樂

Now you might think that once Leucippus and Democritus came up with the general idea of atoms,

現在你可能會認為一旦Leucippus和Democritus發想到原子的一般概念之後

it'd be pretty easy for someone else to take that little, indivisible ball and run with it.

就能讓大家對那個很小的、不可分割的球輕易地瞭若指掌

But you'd be wrong.

那你就錯了

The next major developments in atomic theory didn't come along

從那之後的原子理論發展停滯了將近2300百年之久

for nearly twenty-three hundred years.

幾乎沒有任何進展

I've already told you for instance, about the French chemist, Antoine Lavoisier,

我已經告訴你一個關於法國化學家 Antoine Lavoisier的例子

who proposed the law of Conservation of Mass,

他提出了質量守恆定律

which states that even if matter changes shape or form,

說明物質會改變形狀或型態

its mass stays the same.

但是其質量始終維持不變

And you should remember the English teacher, James Dalton,

而你該記得那位英語老師，James Dalton

who determined that elements exist as discrete packets of matter.

定義了元素以離散物質封包形式存在

Thanks to these, and other great minds, by the 1800's

多虧了這些和其他的偉大的心智

We had a better grip on the general behavior of atoms.

我們對於原子的一般行為有進一步認識

The next logical question was Why?

為什麼原子的一般行為是那樣子？

Why do they behave the way they do?

他們為什麼會有那樣的行為表現呢？

This led to the investigation of atomic structure.

這就展開了對原子結構的調查

In the 1870's, scientists began probing what stuff was made of using discharge tubes.

在1870年代左右，科學家開始用放電管當探針探測各種物質的組成成分

Basically, gas filled tubes with electrodes at each end,

基本上，管子兩端有電極且其內充滿了氣體

which emit light when an electrical current passes through them.

當電流通過其中時就會發出光線

Basically, what a neon light is.

基本上這就是霓虹燈

Because this light was originally produced by a negative electrode or a cathode,

因為這光線最初是由負電極或是陰極產生的

it was called a cathode ray and it had a negative charge.

被稱為陰極射線，帶有負電

But in 1886, German physicist, Eugen Goldstein

但在1886年，德國物理學家，Eugen Goldstein

found that the tubes also emitted light from the positive electrode.

發現管子的正電極也會放射出光線

Basically, a ray heading in the opposite direction,

基本上，就是朝另一個方向放出的射線

which meant that there must also be a positive charge in matter.

也就是說物質當中也帶有正電荷

Goldstein didn't fully understand what he'd discovered here,

Goldstein也並沒有完全了解他所發現的

I mean scientists still hadn't figured out what was responsible for the negative charge in the rays either.

我的意思是科學家仍沒有完全了解為什麼射線中會帶有負電荷

Then English physicist, J.J Thompson took the discharge tube research further.

之後英國物理學家，JJ Thompson藉由量測陰極射線所放出的熱量多寡

By measuring how much heat the cathode rays generated,

以及有多少會被磁場和其他東西給扭曲了

how much they could be bent by magnets and other things,

將放電管的研究更往前帶了一步

he was able to estimate the mass of the rays.

他能夠估計射線的質量

And the mass was about 1,000 times lighter than a hydrogen,

其質量大約是比氫氣要輕上1000倍

the smallest bit of matter known at the time.

是當時所知最小的物質

He concluded that the cathode "rays" weren't rays or waves at all,

他提出陰極射線並不是射線或者是波動的結論

but were in fact, very light, very small negatively charged particles.

而事實上是非常輕、非常小的負電荷粒子

He called them corpuscles.

他稱之為 corpuscles

We call them electrons.

我們稱為電子

So even though we didn't understand what shapes they took,

所以即使我們並不知道它們的外型長怎樣

we knew that they were both negative and positive components to matter.

我們知道物質由正和負電荷的成份組成

The next question was--

接下來就是

How were they arranged in the atom?

它們在原子中如何分布的？

Thompson knew that the atom overall had a neutral charge

Thompson知道原子基本上成電中性

so he imagined that the negatively charged electrons must be distributed randomly

所以他想像帶負電荷的電子一定是隨機分布在

in a positively charged matrix.

一個帶正電荷矩陣中

And the very English Thompson visualized this model as a familiar English dessert.

而那位英國人 Thompson 以英國家喻戶曉的甜點來視覺化這個模型

Plum pudding--

沒錯 -- 李子布丁

the positive matrix being the cake,

帶正電的矩陣就是蛋糕的部份

and the electrons the random, floating bits of fruit within it.

而電子就像是隨機、漂浮在其內的果肉

Even today, Thompson's model of the atom continues to be called "The Plum pudding Model".

甚至到了今天，Thompson的原子模型也繼續地被稱為：「李子布丁模型」

And while a single electron's motion is random,

且單一電子的運動軌跡是隨機的

the overall distribution of them is not.

而整體的電子分布則不是如此

The next big step was taken by New Zealander, Earnest Rutherford in 1909.

下一個將這領域在1909年帶往前跨出一步的是位紐西蘭人，Earnest Rutherford

He designed an experiment using an extremely thin sheet of gold foil and a screen coated with zinc sulfide.

他設計了一個實驗，使用了極薄的金箔和一個鍍上硫化鋅的螢幕

He bombarded the foil with alpha particles,

他用alpha粒子轟炸撞擊那金箔

which he didn't really know what they were,

他其實也不確定打到哪些點

just that they were produced by the decay of radium.

只能在之後發現由輻射衰變後的產物來判斷

They were positively charged and they were really, really small.

它們帶著正電且體積非常、非常小

He expected them to just fly right through the foil with no deflection,

他預期它們會正好穿過金箔而不會有任何反射發生

and many of them did just that.

而它們大多結果也真的是這樣

But as it turned out, some of the particles were deflected at large angles

但是結果變成有些粒子在很大的角度上有反射發生

and sometimes, almost straight backward.

且有時幾乎是完全反方向彈回來

The only explanation for this was that the entire positive charge in an atom,

這唯一的解釋就是位在原子中會排斥alpha粒子

the charge that would repel a alpha particle,

的全部正電荷

must be concentrated in a very small area.

一定集中在一個很小的區域當中

An area that he called, the nucleus.

那個區域就叫做，原子核

Because most of the alpha particles passed right through the atom undeterred,

因為大部分的alpha粒子會不受影響地直直穿過原子

Rutherford concluded that most of the atom is empty space!

Rutherford因此下結論說原子佔據的大部分空間其實是空的

And he was correct!

他是對的！

Rutherford would later discover that if he bombarded nitrogen with alpha particles,

Rutherford 之後就發現了若是用alpha粒子轟擊氮原子

it created a bunch of hydrogen ions.

就會產生許多的氫離子

Now, he correctly surmised

他正確地假設

that these tiny, positively charged ions were themselves, fundamental particles.

這些微小帶正電的離子就是它們自己的基本粒子

Protons

質子

Now we're getting close to reality!

現在我們離現實更靠近了！

So these chemists had a fairly good idea of the structure of the atom,

這些化學家對於原子的結構有不錯的想法

they just needed to figure out what exactly the electrons were doing.

他們只要了解電子在其中扮演的角色就完成了

Enter Niels Bohr!

Niels Bohr 登場！

In 1911, the same year the results of Rutherford's gold foil experiment were published,

1911年，Rutherford發表金箔實驗結果的同一年

Bohr traveled to England to study with Rutherford.

Bohr 前往英國與 Rutherford一起做研究

And as a physicist, he was also interested in the mathematical model

身為一個物理學家，他同時也對德國物理學家 Max Plank 和 Albert Einstein

set forth by German physicists, Max Plank and Albert Einstein

用來解釋電磁能的行為的

to explain the behavior of electromagnetic energy.

的數學模型感興趣

Over time, Bohr came to realize that these mathematical principles could be applied to Rutherford's atom model.

隨著時間推進，Bohr慢慢了解到這些數學原理可以應用在Rutherford的原子模型中

His analysis of the gold foil experiment,

他對於金箔實驗的分析

calculations based on the proportion of alpha particles that went straight through,

基於對那些直接穿透原子的、

those that were slightly deflected,

那些微微偏移的

and those that bounced almost completely backward,

和那些幾乎朝入射方向180度反彈回來的那些alpha粒子的比例所做的計算

allowed him to predict the most likely positions of the electrons within the atom.

讓他能夠去預測電子在原子當中最可能出現的位置

Bohr's resulting model, sometimes called the planetary model, is still familiar to most people,

Bohr的結果模型，有時被稱為行星模型，仍廣為人知

probably including you.

也許也包括你

It represents the electrons in orbits around a small, central nucleus.

這麼模型顯示了電子圍繞一個在中心的原子核外圍的軌道運行

Each orbit can have a specific number of electrons,

每個軌道有特定數量的電子

which correlates to the energy levels and orbitals in the modern model of an atom.

與現代原子模型中它們的能階和運行軌道相關

And while it's definitely flawed,

一定不是完美無缺的模型

Bohr's model is very close to reality in some important ways.

但是Bohr的模型在某幾個重要的方面也已經非常接近真實狀況

But unlike everyone that I've mentioned in the past couple of minutes,

但不像我過去幾分鐘所提到的那些人

Bohr was at once fantastically right

Bohr 曾一度是對的

and way off.

但也還差遠了

The problem was those pesky electrons.

問題就是那些麻煩的電子

It was the German theoretical physicist, Werner Heisenberg,

德國的理論物理學家Werner Heisenberg

who got everyone to understand just how huge and mind-blowing this electron problem was.

讓大家了解到這個電子問題有多大且多令人傻眼

But he was also the one who helped tie the whole mess up into a neat, little bundle.

但他也是幫助大家了解、整理這個難搞的問題變成簡潔且簡化

Using his wicked math chops,

使用他的邪惡數學大刀一揮

Heisenberg discovered that it is impossible to know with certainty

Heisenberg發現要知道電子的動量或者任何次原子粒子

both the momentum of an electron or any sub-atomic particle

的準確值以及其準確的位置

and its exact position.

是不可能的事

And the more you know about one of those two variables,

而你月了解這兩個變量的其中一個時

the harder it gets to measure the other one.

你就越難量測另一個

So if you can't measure the position or momentum of an electron,

所以你無法同時測量一個電子的位置和動量

you obviously can't say with certainty that the electrons in an atom are all neatly aligned in circular orbits.

很明顯地你不能確定說在原子中的電子都在軌道上排列的非常整齊

So he and the new wave of physicists and chemists proposed a new theory.

所以他和新的一代物理學家和化學家提出了一個新的理論

A quantum theory,

量子理論

which proposes that electrons weren't particles or waves,

假設電子並不是粒子或者波動

instead, they had properties of both and neither.

而是同時有兩者的性質或者都沒有

By this thinking, the arrangement of electrons around a nucleus could only be described

思考這個假設，要描述原子核外電子的排列

in terms of probability.

就只能用機率分布的方式了

In other words, there are certain regions where an electron is much more likely to be found.

換句話說，電子會在某幾個特定的區域比較容易被找到

We call these regions orbitals.

我們稱之為軌域區域

You know, the very same orbitals that you and I have been talking about.

就是我們剛討論的那個軌道

The ones that go by the names 's' and 'p' and 'd' and 'f',

分別標記為"s"、"P"、"d"和"f"

and that forms sigma and pi bonds.

而有兩種鍵結 sigma 和 pi 鍵結

Those are the things that Heisenberg's theory predict,

這些都是Heisenberg理論中所預測到的

and that's the modern understanding of atoms.

也是我們現代對原子的了解

Because it's based of probability,

由於這奠基於機率分布

quantum style atoms are often drawn as clouds,

原子的量子性質常常都被以雲的方式表示

with the intensity of color representing not individual electrons,

以顏色的深淺而非以個別電子的方式表示

but the probability of finding an electron in any particular position.

而事在特定位置發現電子的機率

For this reason, the quantum model is often called the cloud model of the atom.

由於這原因，量子模型就常被稱為原子雲模型

AND NOW YOU KNOW!!

所以現在你瞭了吧！！

All the people I've mentioned and many others

我提過的所有人和其他很多人

put their heads together over time to build current--

聚集起來致力於創造一股潮流

and I might say--quite elegant understanding of atomic theory.

而我必須說，是對原子理論的一種非常優雅的理解

Now after 2,500 years, even though we can't see them,

兩千五百年後的現在，雖然我們仍看不見電子

we can know what they're like and how the work

因為有前仆後繼的科學家的各自貢獻，而組成一幅完整、漂亮的圖像

because a long succession of scientists contributed bits and pieces to the whole, fantastic picture.

我們可以知道它們像什麼樣子以及它們扮演什麼角色

But it's also important to recognize that we still may not be quite all the way right.

但了解到我們仍不完全了解所有的事情也很重要

Thompson's contemporaries were sure that the Plum pudding model was right,

Thompson同時代的人認為李子布丁模型是對的

scientists in Bohr's day fully believed that the planetary model was right

Bohr時代的人完全相信行星模型是對的

and today, we're extremely confident that the quantum model is correct.

而今天，我們極度自信的認為量子模型是正確的

But it may not be all the way correct

但也許這部全對

and that's were you come in.

而這也是你所參與的位置

The only way we can go on being sure is to keep asking questions and conducting experiments.

唯一能夠繼續進一步了解原子理論的方式就是透過不斷地問問題和做實驗

That's why you're taking chemistry and physics!

而那也是你為什麼要上化學課和物理課的理由！

Pay attention!

專心點！

Thank you for watching this episode of Crash Course Chemistry!

謝謝你看這集化學速成課程！

If you paid attention, you learned that Leucippus and Democritus originated the idea of atoms

你若有專心上課，你會學到大約在2,500年前Leucippus和Democritus

nearly 2,500 years ago.

創始了原子的概念

But that the real work didn't really begin until both protons and electrons were discovered.

但真的對於原子有更多了解要到發現質子和電子之後了

By experimenting with discharge tubes,

藉由放電管的實驗

and how Earnest Rutherford figured out what, and where the nucleus is.

一級Earnest Rutherford了解原子核是什麼東西後

You also learned that sometimes chemistry can be done with just math,

你也學到了有時化學可以直接以數學形式理解

like how Bohr figured out his model or how the way that Heisenberg

就像Bohr了解他自己的模型或者Heisenerg如何

used math to usher in the quantum theory of the atom.

用數學了解以推導出原子的量子理論

This episode was written by Edi Gonzalez and edited by Blake de Pastino,

這集由Edi Gonzalez撰寫及Blake de Pastino編輯

Our chemistry consultant is Dr. Heiko Langner

我們的化學顧問式Dr. Heiko Langner

And it was filmed, edited, and directed by Nicholas Jenkins.

由Nicholas Jenkins拍攝、編輯和執導

The script supervisor was Katherine Green

腳本監督為Katherine Green

Michael Aranda is our sound designer

Michael Aranda是聲音設計

and Thought Cafe is our graphics team.

以及我們的動畫團隊是Thought Cafe