Radioactivity: Expect the unexpected - Steve Weatherall

Summary

The video script delves into the fascinating world of radioactivity, explaining how unstable atomic nuclei can spontaneously transform into different elements by emitting particles like alpha and beta. It highlights radioactivity's applications in everyday life, such as smoke detectors and medical imaging, as well as its potential dangers, like DNA damage. The script also touches on the use of radioactive heat for power generation and the varying levels of ionization caused by different types of radiation.

Takeaways

• 🔬 Radioactivity is a process where the nucleus of an atom changes spontaneously from one element to another.
• 💡 The nucleus, made of protons and neutrons, is typically stable, but certain nuclei can change suddenly and emit particles.
• ⚛️ Beta particles are fast-moving electrons that are emitted when a neutron in the nucleus changes into a proton.
• 💥 Alpha particles are heavier and slower than beta particles, consisting of two protons and two neutrons, essentially a helium nucleus.
• 🚒 Alpha particles are used in smoke detectors, which are safe as they cannot travel far in air.
• 🏥 Beta particles are used in medical tracers to track the movement of chemicals in the body, with enough energy to be detected outside the body.
• 🌟 Gamma rays are electromagnetic waves, similar to light but more energetic, and can pass through the body.
• 🍇 Gamma radiation is used to kill bacteria in food to extend shelf life and to target cancer cells in radiotherapy.
• 🔥 Radioactive substances generate heat, which can be harnessed for power, such as in space probes and pacemakers.
• ⚡ Ionization is the damage caused to atoms when radiation is slowed down abruptly, with alpha particles causing the most and gamma the least.
• ☢️ Radiation can be harmful to humans, especially when inhaled or ingested, as it can damage DNA.

Q & A

What is the process where an element spontaneously changes into another element called?

The process is called radioactivity.

What are the particles that make up an atom's nucleus?

The nucleus is made up of protons and neutrons.

What is the difference between the behavior of electrons and nuclei when atoms bond together?

While atoms can share or swap electrons when they bond, the nuclei themselves do not change.

What happens when a radioactive nucleus is unstable?

An unstable radioactive nucleus may change suddenly and spontaneously, emitting a small particle and transforming into another element.

How does a carbon nucleus turn into a nitrogen nucleus?

A carbon nucleus can eject a fast-moving electron and turn into a nitrogen nucleus.

What are the two different particles that can be emitted from radioactive nuclei?

The two different particles are beta particles and alpha particles.

What is a beta particle and how is it formed?

A beta particle is a very fast electron that is emitted when a neutron in the nucleus spontaneously changes into a proton.

What is an alpha particle and what is it composed of?

An alpha particle is a particle that is 8,000 times more massive than a beta particle and is composed of two protons and two neutrons.

How are alpha particles used in everyday life?

Alpha particles are used in smoke detectors, which contain a source of alpha particles, such as radioactive Americium.

What is the third type of nuclear radiation mentioned in the script?

The third type of nuclear radiation is gamma radiation.

How does gamma radiation differ from alpha and beta particles?

Gamma radiation is not a particle but an electromagnetic wave, similar to microwaves or light, but 1,000 times more energetic.

What is ionization in the context of nuclear radiation?

Ionization is the damage done to atoms when nuclear radiation is abruptly slowed down.

What are the potential health consequences of inhaling or ingesting a radioactive nucleus?

The health consequences can be severe, as radiation can cause damage to DNA.

Outlines

00:00

🔬 Radioactivity Basics

The paragraph introduces radioactivity, a process where the nucleus of an atom changes spontaneously from one element to another. It explains that while atoms typically remain stable, certain nuclei are unstable and can emit particles such as beta and alpha particles. Beta particles are high-speed electrons resulting from a neutron turning into a proton within the nucleus, while alpha particles are heavier, slower particles composed of two protons and two neutrons. The paragraph also touches on the unexpected nature of these transformations and their potential uses in everyday life.

Keywords

💡Radioactivity

Radioactivity refers to the spontaneous emission of particles or electromagnetic radiation from unstable atomic nuclei. It is the central theme of the video, illustrating how certain elements can transform into others. The script mentions that 'the nucleus of the chemical elements is not always fixed' and can 'change spontaneously from one element to another', highlighting the transformative power of radioactivity.

💡Nucleus

The nucleus is the central part of an atom, composed of protons and neutrons. It is much smaller than the atom itself, yet it contains most of the atom's mass. The video script explains that 'the nuclei themselves never change' during chemical reactions, but this is not always the case with radioactive elements, which can undergo changes in their nuclei.

💡Protons

Protons are subatomic particles found in the nucleus of an atom, carrying a positive electric charge. They are mentioned in the script as one of the particles that make up the nucleus. The video also discusses how a neutron can spontaneously change into a proton, which is a key process in beta particle emission.

💡Neutrons

Neutrons are subatomic particles in an atom's nucleus that have no electric charge. They are discussed in the context of radioactivity, where they can spontaneously change into protons, leading to the emission of beta particles. This process is contrary to what is typically taught in chemistry, where neutrons are considered stable within the nucleus.

💡Electrons

Electrons are subatomic particles that orbit the nucleus of an atom and carry a negative electric charge. They are mentioned in the script as particles that can be shared or swapped during chemical bonding but are not typically found within the nucleus. However, in the case of beta particle emission, an electron can be emitted from the nucleus when a neutron changes into a proton.

💡Beta Particles

Beta particles are high-speed electrons emitted from the nucleus during radioactive decay. The script explains that beta particles are produced when a neutron in the nucleus changes into a proton, and the resulting electron is emitted as a beta particle. They are an example of how radioactivity can lead to the transformation of one element into another.

💡Alpha Particles

Alpha particles are emitted from the nucleus of a radioactive element and consist of two protons and two neutrons. The video script describes them as being much more massive than beta particles and slower in speed. Alpha particles are helium nuclei, and their emission leads to the transformation of one element into another, as seen in the script's example of uranium decay.

💡Americium

Americium is a synthetic radioactive chemical element used in smoke detectors, as mentioned in the script. It emits alpha particles, which are safe in the context of a smoke detector because they cannot travel far in air. Americium is an example of how radioactive materials can be harnessed for practical, everyday uses.

💡Gamma Rays

Gamma rays are a form of high-energy electromagnetic radiation emitted during radioactive decay. Unlike alpha and beta particles, gamma rays are not particles but waves. The script explains that gamma rays are used in food preservation to kill bacteria and in medical treatments to target cancer cells. They are also noted for their high penetrating power, which can be both beneficial and harmful.

💡Ionization

Ionization is the process by which radiation strips electrons from atoms or molecules, creating ions. The video script mentions that the more abrupt the slowing down of nuclear radiation, the more ionization occurs. Alpha particles cause the most ionization due to their mass and charge, while gamma rays cause the least. Ionization is a key mechanism through which radiation can damage biological tissues, including DNA.

💡DNA Damage

DNA damage refers to alterations to the DNA molecule that can be caused by various factors, including radiation. The script warns that while alpha particles cannot penetrate the skin, if inhaled or ingested, they can cause severe health consequences by damaging DNA within the body. This highlights the dual nature of radioactivity as both a tool and a hazard.

Highlights

Radioactivity is a process where the nucleus of an element can change spontaneously from one element to another.

The nucleus is made of protons and neutrons, with electrons orbiting around it.

Nuclei never change when atoms bond, except in the case of certain unstable nuclei.

Unstable nuclei can spontaneously emit particles and transform into another element.

Carbon can eject an electron and turn into nitrogen as an example of radioactivity.

Beta particles are emitted when a neutron in the nucleus changes into a proton and the electron is released.

Alpha particles are emitted from unstable nuclei and are 8,000 times more massive than beta particles.

Alpha particles consist of two protons and two neutrons, essentially helium nuclei.

Smoke detectors contain a source of alpha particles, which are safe and cannot travel far in air.

Beta particles can penetrate materials and are used in medicine to trace chemicals in patients.

Gamma radiation is not a particle but an electromagnetic wave, more energetic than visible light.

Gamma rays are used to kill bacteria in food and cancer cells in radiotherapy.

Radioactive substances generate heat that can be used for power, such as in space probes and pacemakers.

Ionization is the damage caused to atoms when nuclear radiation is slowed down.

Alpha particles cause the most ionization due to their mass and speed.

Gamma rays cause the least ionization and can pass through the body.

The most serious effect of radiation in humans is DNA damage.

Radioactivity is both useful and deadly, and is a part of the natural world's background.

Transcripts

Transcriber: Andrea McDonough Reviewer: Bedirhan Cinar

It is only in the last 100 or so years that human kind has understood

that the nucleus of the chemical elements is not always fixed.

It can change spontaneously from one element to another.

The name for this process is radioactivity.

You probably already know something about the nucleus:

it's much tinier than the atom,

it's made of particles called protons and neutrons,

there are electrons orbiting around it.

And though the atoms can share or swap electrons when they bond together,

the nuclei themselves never change.

Right?

Well, no.

Certain nuclei are not stable in that way.

This means they may change suddenly,

spontaneously.

The radioactive nucleus flings out a small particle

and transforms into another element, just like that.

For example,

the carbon nucleus can eject a fast-moving electron

and turn into a nitrogen nucleus.

There are two different particles that can be emitted from radioactive nuclei,

but never together.

The very fast electron is known as a beta particle.

If you know a little bit about electrons, you may be thinking,

"What was the electron doing in the nucleus in the first place?"

The answer is there is a neutron in nucleus

spontaneously changed into a proton,

which stayed behind,

and the electron flew out as a beta particle.

This is not what chemistry has taught us to expect.

The nucleus is supposed to be stable.

Neutrons don't change into protons.

Except, sometimes they do!

The other particle it emits spontaneously

from an unstable nucleus is alpha.

An alpha particle is 8,000 times more massive than beta,

and it's a bit slower.

Alpha is made from two protons and two neutrons.

If we trap all those alpha particles together,

we get helium gas.

Alpha is a helium nucleus.

Like the beta particle, you would not have expected

a heavier nucleus to throw out helium.

But again, it happens,

and the nucleus becomes a new element.

So, is radioactivity useful or just dangerous?

Wherever you are sitting,

it is quite likely that there is a device nearby

which contains a source of alpha particles:

a smoke detector.

The source is radioactive Americium.

You are totally safe from these alpha particles,

which cannot travel more than a few centimeters in air.

Beta particles penetrate much farther

through materials than alpha can.

Radioactive atoms are used in medicine as traces,

to show where chemicals travel in the patient.

Beta particles are emitted and have enough energy

to emerge from the body and be detected.

There is a third type of nuclear radiation:

gamma, which is not a particle at all.

It is an electromagnetic wave,

like microwaves, or light,

but it is actually 1,000 times more energentic than visible light.

Gamma rays may pass right through your body.

Gamma is used to zap the bacteria in fruit to increase its shelf life,

or in radiotherapy to kill cancer cells.

Radioactive substances get hot,

and this heat can be used to generate power.

This heat has been brought to you since space probes,

and, in the past, in pacemakers for hearts.

The more abruptly nuclear radiation is slowed down,

the more damage it does to the atoms it hits.

This is called ionization.

Alpha causes the most ionization as it crashes into other atoms

and gamma the least.

In humans, the most serious effect of radiation

is the damage that it can cause to our DNA.

Although alpha cannot penetrate your skin,

if you inhale or injest a radioactive nucleus,

the health consequences can be severe.

Radioactivity is both useful and deadly,

but it is all around us as a background to the natural world.