How the Proton was Discovered

Summary

Ernest Rutherford, a renowned scientist post-WWI, is celebrated for his Nobel-winning discovery of alpha and beta radiation and the gold foil experiment that debunked the plum pudding model of the atom. His most significant post-war work involved developing a directional hydrophone and later, through experiments with alpha particles and light elements, he inadvertently split the atom. Rutherford's findings, published in 1919, led to the understanding of atomic nuclei composed of 'stable alphas' and hydrogen ions, and predicted isotopes' existence. His work laid the foundation for modern atomic theory.

Takeaways

• 🏆 Ernest Rutherford was renowned in science for his Nobel Prize-winning work on alpha and beta radiation and his gold foil experiment, which disproved the plum pudding model of the atom.
• 🔬 Rutherford's gold foil experiment with Hans Geiger and Ernest Marsden led to the discovery that electrons orbit a positively charged nucleus, revolutionizing atomic theory.
• 🔧 After developing a directional hydrophone, Rutherford returned to radiation research in 1917, focusing on alpha particle scattering when interacting with light elements.
• 🤫 Rutherford had a secret plan to split the atom, as revealed in a private letter to Neils Bohr.
• 🧪 He conducted experiments using a chamber with a slider for a radium C source and a zinc sulfide screen to observe scintillations.
• 🌫️ Rutherford filled the chamber with different gases and adjusted the slider to find a relationship between scintillations and the distance of the radium C from the screen.
• 🤔 He discovered unusual scintillations when the radium C was far from the screen and found these were caused by positively charged particles similar to hydrogen atoms.
• 🔍 After ruling out other sources, Rutherford concluded that alpha particles interacting with atmospheric nitrogen produced these particles, suggesting nitrogen atom disintegration.
• 💥 Rutherford's findings indicated that the nitrogen nucleus disintegrated, releasing hydrogen atoms, thus achieving the first artificial nuclear transmutation.
• 📚 His results were published in 1919, and he proposed the nucleus was constructed from 'stable alphas' and hydrogen ions, predicting the existence of isotopes.
• 🌧️ The cloud chamber invented by Charles Thomson Rees Wilson was used by Rutherford to observe alpha particle tracks, confirming his proton proposal.

Q & A

Who was Ernest Rutherford and what were his main contributions to science?

Ernest Rutherford was a prominent scientist known for his Nobel Prize-winning work in discovering and characterizing alpha and beta radiation, and for his gold foil experiment which disproved the plum pudding model of the atom, introducing a new model with electrons orbiting a positively charged nucleus.

What was the purpose of Rutherford's directional hydrophone?

Rutherford developed a directional hydrophone for the detection of submerged submarines during World War I, which was a significant contribution to military technology at the time.

What was the nature of the scintillations observed by Rutherford in his experiments?

Scintillations were flashes of light produced on a zinc sulfide screen when alpha particles from radium C or ionized particles from the air hit it. Rutherford noticed different types of scintillations when the radium C source was placed at a long distance from the screen.

What did Rutherford discover about the particles causing the scintillations at a long distance from the radium C source?

Rutherford discovered that the particles causing these scintillations were positively charged, were deflected by magnetic fields, and carried the same amount of energy as a hydrogen atom.

How did Rutherford's initial hypothesis about the particles differ from his final conclusion?

Initially, Rutherford thought he had discovered a new form of radiation. However, after further tests, he concluded that the particles were hydrogen atoms resulting from the disintegration of nitrogen atoms when they collided with alpha particles.

What role did the cloud chamber play in Rutherford's work and in the confirmation of his findings?

The cloud chamber, invented by Charles Thomson Rees Wilson, was used by Rutherford to observe tracks made by alpha particles. It was later used by Patrick Blackett to confirm Rutherford's proposal of the proton by showing the conversion of nitrogen into an isotope of oxygen after collision with and absorption of an alpha particle.

What was the significance of Rutherford's discovery of the hydrogen atom in the nitrogen nucleus?

Rutherford's discovery that nitrogen atoms could disintegrate to form hydrogen atoms upon collision with alpha particles was significant as it demonstrated the possibility of splitting the atom and laid the groundwork for further understanding of atomic structure and nuclear reactions.

What predictions did Rutherford make regarding the nucleus and isotopes?

Rutherford proposed that the nucleus is constructed through stable alphas and hydrogen ions. He also predicted the existence of a neutral particle, which would later be confirmed and is now known as the neutron, to account for the existence of isotopes.

What recognition did Rutherford receive for his work, and were his later discoveries as significant as his earlier ones?

Rutherford received a Nobel Prize for his work on alpha and beta radiation but did not win a second Nobel Prize for his later discoveries. However, his later work was arguably as important, if not more so, as it significantly contributed to the understanding of modern atomic theory.

How did Rutherford's work influence the field of physics and the understanding of atomic structure?

Rutherford's work revolutionized the understanding of atomic structure by introducing the nuclear model of the atom and demonstrating the possibility of atomic transmutation. His findings laid the foundation for nuclear physics and the development of atomic theory.

Outlines

00:00

🏆 Ernest Rutherford's Atomic Discoveries

Ernest Rutherford was a prominent scientist post-World War I, renowned for his Nobel Prize-winning work on alpha and beta radiation and the gold foil experiment that debunked the plum pudding model of the atom. In 1917, he returned to radiation research, focusing on alpha particle scattering with light elements. Rutherford conducted experiments with a directional hydrophone and a chamber filled with various gases, observing scintillations on a zinc sulfide screen. He discovered a new type of scintillation at a long distance from the radium C source, which were positively charged particles similar to hydrogen atoms. Through a series of tests, Rutherford concluded that alpha particles interacting with nitrogen atoms resulted in the disintegration of nitrogen and the release of hydrogen atoms, effectively splitting the atom for the first time. His findings were published in 1919, and he proposed the nucleus was made of stable alphas and hydrogen ions, predicting the existence of a neutral particle, later known as the neutron.

05:02

🌧️ The Cloud Chamber and Rutherford's Legacy

During the same period, Charles Thomson Rees Wilson's cloud chamber invention was utilized by Rutherford to observe alpha particle tracks, which became instrumental in Patrick Blackett's confirmation of Rutherford's proton proposal. Blackett demonstrated that nitrogen could be converted into an oxygen isotope with the emission of a proton upon alpha particle collision. Although Rutherford did not receive a second Nobel Prize for his later discoveries, they were pivotal to modern atomic theory. The video encourages viewers to like and subscribe for more content on scientific advancements of the era.

Keywords

💡Ernest Rutherford

Ernest Rutherford was a New Zealand-born British physicist who is considered one of the fathers of nuclear physics. His work on the discovery and characterization of alpha and beta radiation earned him the Nobel Prize in Chemistry in 1908. In the context of the video, Rutherford's experiments with Hans Geiger and Ernest Marsden led to the disproof of the plum pudding model of the atom, proposing instead a model with electrons orbiting a positively charged nucleus.

💡Alpha and beta radiation

Alpha and beta radiation are two types of radioactive decay processes. Alpha radiation consists of helium nuclei, while beta radiation involves electrons or positrons. Rutherford's Nobel Prize-winning work involved the discovery and characterization of these forms of radiation, which are central to understanding atomic structure and the script's narrative of his scientific achievements.

💡Plum pudding model

The plum pudding model was an early atomic model proposed by J.J. Thomson, which likened the atom to a plum pudding with negatively charged 'plums' (electrons) scattered through a 'pudding' of positive charge. The video script explains how Rutherford's gold foil experiment disproved this model, leading to a new understanding of atomic structure.

💡Gold foil experiment

The gold foil experiment was a pivotal study conducted by Hans Geiger and Ernest Marsden under Rutherford's guidance. It involved firing alpha particles at a thin gold foil and observing their scattering. The results of this experiment, as mentioned in the script, led to the rejection of the plum pudding model and the proposal of a new atomic model.

💡Hydrophone

A hydrophone is a device designed to detect and locate underwater objects, such as submarines, by listening for the sounds they produce. In the script, it is mentioned that Rutherford developed a directional hydrophone after the end of the First World War, showcasing his contributions to both science and military technology.

💡Scintillations

Scintillations refer to the flashes of light produced when a charged particle strikes a fluorescent screen. In the video script, Rutherford used a zinc sulfide screen to observe scintillations caused by alpha particles, which led to his discovery of a new form of radiation and his pursuit to split the atom.

💡Radium C (Bismuth 214)

Radium C, now known as Bismuth 214, is a radioactive isotope that decays by emitting alpha particles. In the script, Rutherford used a source of Bismuth 214 in his experiments to study alpha particle interactions, which ultimately led to his discovery of the proton.

💡Isotopes

Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons. Rutherford predicted the existence of isotopes in his papers, as mentioned in the script, to account for the variations in atomic mass without changes in chemical properties, a concept that was later confirmed by other physicists.

💡Cloud chamber

A cloud chamber is a device used to visualize the paths of ionizing particles, such as alpha particles. Invented by Charles Thomson Rees Wilson, the cloud chamber was used by Rutherford to observe particle tracks, as described in the script, and played a crucial role in confirming his theories about atomic structure.

💡Proton

A proton is a subatomic particle found in the nucleus of an atom, carrying a positive electric charge. Rutherford's experiments led to the discovery of the proton, as he deduced that the hydrogen atom was a constituent part of the nitrogen nucleus, as stated in the script.

💡Nuclear physics

Nuclear physics is a subfield of physics that studies the structure and properties of atomic nuclei and the particles that constitute them. The script's main theme revolves around Rutherford's contributions to nuclear physics, including his work on atomic structure and his experiments that led to the discovery of the proton.

Highlights

Ernest Rutherford became renowned in science for his Nobel prize-winning work and the gold foil experiment.

Rutherford discovered and characterized alpha and beta radiation, earning him the Nobel Prize.

The gold foil experiment disproved the plum pudding model of the atom, introducing a new model with electrons orbiting a nucleus.

Rutherford developed a directional hydrophone for submarine detection post-World War I.

He returned to radiation research in 1917, focusing on alpha particle scattering with light elements.

Rutherford had a secret plan to split the atom using alpha particles, as mentioned in a private letter to Neils Bohr.

He conducted experiments with a chamber, slider, and radium C (now known as bismuth 214) to study alpha particle interactions.

Rutherford observed different scintillations when radium C was far from the zinc sulfide screen.

He discovered positively charged particles with the same energy as hydrogen atoms, initially thought to be a new form of radiation.

Rutherford ruled out hydrogen presence in the atmosphere and various gases as the source of the intriguing particles.

He concluded that alpha particles interacting with atmospheric nitrogen produced particles similar to hydrogen.

Rutherford stated that nitrogen atoms disintegrated, releasing hydrogen atoms as part of the nucleus.

He proposed that the nucleus is constructed from stable alphas and hydrogen ions, predicting the existence of isotopes.

Rutherford's findings were published in a series of papers in 1919, contributing to modern atomic theory.

The cloud chamber, invented by Charles Thomson, was used by Rutherford to observe alpha particle tracks.

Patrick Blackett confirmed Rutherford's proposal of the proton by demonstrating nitrogen's conversion into oxygen after alpha particle collision.

Though Rutherford did not win a second Nobel Prize, his later work was vital for understanding atomic theory.

Transcripts

by the end of the first world war Ernest

ruford had become one of the biggest

names in science for two main reasons

the first being his Nobel prizewinning

work in which he discovered and

characterized Alpha and beta radiation

and the second being his famous gold

foil experiment with Hans gger and

Ernest maren that disproved the plump

putting model of the atom and introduced

a new model in which electrons orbit

around a positively charged nucleus but

arguably his biggest accomplishment with

from after the end of the Great War

after 2 years of developing a

directional hydrophone for the detection

of submerged submarines he returned to

radiation research in 1917 on how alpha

particles scatter when interacting with

Light Elements Rutherford had a secret

plan though with these experiments which

he privately mentioned to Neil's bore in

a letter I am also trying to break up

the atom by this method regard this as

private

ruer quickly got to work on a setup a

chamber in which inside laid a slider

that allowed ruer to move back and forth

a source of what was known at the time

as radium C known today as bismuth 214

at one end of the chamber was a small

opening with a zinc sulfide screen which

would produce flashes of light known as

scintillations when alpha particles from

the radium C or ionized particles from

the air would hit the screen Rutherford

filled this chamber with different gases

along with air of varying humidities and

adjust the slider to try and find some

sort of relationship between the amount

of scintillations measured in the

distance the radium C was from the zinc

sulfide screen after doing this reord

did in fact find something strange that

would help him in his pursuit of

splitting the

atom what he noticed was that

scintillations of a different nature

would occur when the radium C Source was

placed a very long distance from the

screen

after examining these scintillations and

running further tests he determined that

the particles causing these

scintillations were positively charged

were deflected by magnetic fields and

carried the same amount of energy as

that of a hydrogen atom at this point

Rutherford initially thought he had

discovered a new form of radiation but a

series of continued tests led him to

come to a much different conclusion

after determining the nature of the

Intriguing particle ruer went to work to

try and find way where it was coming

from since hydrogen wasn't known to have

a considerable presence in the

atmosphere other than possibly through

water vapor he filled the chamber with

only carbon dioxide and then with only

oxygen but found that from only these

gases present these scintillations did

not occur at all this led him to rule

out those gases as well as a new kind of

radiation since the radium Source was

then ruled out as the sole cause of

these particles it started to seem like

water vapor would end up up being the

answer but Rutherford was hit with a

confounding result after more tests he

eventually ruled out water vapor as a

candidate for after comparing

scintillations from humid air with

scintillations from dry air the amount

of scintillations was only slightly

reduced meaning scintillations were

still happening even with the absence of

water vapor in the air after ruling out

most of the main components of the

atmosphere Rutherford was left with only

one option for the cause of these

cellation

an interaction was happening between

alpha particles and Atmospheric nitrogen

producing an ionized particle that seems

to behave very similarly to that

hydrogen

atom upon seeing these results

Rutherford stated in one of his papers

we must conclude that the nitrogen atom

disintegrated and that the hydrogen atom

which is liberated formed a constituent

part of the nitrogen nucleus even though

Rutherford concluded that the nitrogen

atoms that collided trans trans mutated

even though he called it disintegrated

at the time he did in fact conclude that

the alpha particle survived and did not

transmutate another quote from

Rutherford in one of his papers States

considering the enormous intensity of

the forces brought into play it is not

so much a matter of surprise that the

nitrogen atom should suffer

disintegration as that the alpha

particle itself escapes disruption into

its

constituents whether or not the

conclusions he made from these

experiments were accurate one thing was

certain Rutherford had split the atom

for the first time releasing hydrogen

from nitrogen through a high energy

collision with an alpha particle these

results were published by Rutherford

through a series of four papers in 1919

and one year after that he proposed that

the nucleus is constructed through what

he called stable alphas and hydrogen

ions and also predicted the existence of

a neutral particle to account for the

existence of Isotopes both of these

predictions would be confirmed later by

Future

physicists around the same time a new

invention was being put to good use the

cloud chamber invented by Charles

Thompson ree Wilson Rutherford used this

Cloud chamber to observe tracks made by

alpha particles and the Chamber would

later end up being used by Patrick

blackit to confirm Rutherford's proposal

of the proton by showing that nitrogen

was converted into an isotope of oxygen

after collision with and absorption of

alpha particle while releasing a proton

in the process Rutherford never won a

second Nobel Prize for his discoveries

after Alpha and beta radiation but the

discoveries he made were arguably just

as important if not more important than

his first and his later work served as a

vital contribution to the understanding

of modern atomic

theory if you enjoyed this video please

consider liking and subscribing click

here if you want to see more scientific

progress made during during this time

period thank you for watching and I will

see you in the next video