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Rutherford and the proton
In 1919 Ernest Rutherford carried out the first ever transmutation of one element into another. Alpha particles were bombarding nitrogen and forming oxygen along with hydrogen.
Ernest Rutherford - Early Radioactivity
Ernest Rutherford - Strikes Again (not as good as the T.E.S.B.)
7.1 Sub Pages
A Big Broad Overview:
Test Your Understanding of Atomic Structure:
Test Your Understanding of Atomic Structure:
Successfully completing each of the games (3 types + random) will provide enough understanding for the course.
Islands of Stability
Islands of Stability
The chart to the left shows the chart of nuclides for the first ten elements. Number of protons is on the y-axis, number of neutrons is on the y-axis. Stable nuclides are shown in grey. Unstable nuclides decay of these elements decay either by emitting a beta minus or beta plus particle.
Using the simulation above, test the stability of the isotopes.
What patterns develop as you create more isotopes?
Propose a rule to predict stable isotopes beyond those shown on the chart to the left.
Decay particles
Decay particles
Unstable nuclides will decay into more stable nuclei by emitting one or more of the following particles/radiation:
2 Protons + 2 Neutrons
Alpha radiation occurs when an atom undergoes radioactive decay, giving off a particle (called an alpha particle) consisting of two protons and two neutrons (essentially the nucleus of a helium-4 atom), changing the originating atom to one of an element with an atomic number 2 less and atomic weight 4 less than it started with. Due to their charge and mass, alpha particles interact strongly with matter, and only travel a few centimeters in air. Alpha particles are unable to penetrate the outer layer of dead skin cells, but are capable, if an alpha emitting substance is ingested in food or air, of causing serious cell damage. Alexander Litvinenko is a famous example. He was poisoned by polonium-210, an alpha emitter, in his tea.
Alpha radiation: The emission of an alpha particle from the nucleus of an atom
two types: electron (beta minus) or positron (beta plus)
Beta radiation takes the form of either an electron or a positron (a particle with the size and mass of an electron, but with a positive charge) being emitted from an atom.
If a nucleus undergoes 𝜷- decay a neutron decays into a proton, electron and antineutrino. The resulting daughter nuclei then has one additional proton (Z+1), but an identical atomic mass (A).
Due to the smaller mass, it is able to travel further in air, up to a few meters, and can be stopped by a thick piece of plastic, or even a stack of paper. It can penetrate skin a few centimeters, posing somewhat of an external health risk. However, the main threat is still primarily from internal emission from ingested material.
Beta radiation: The emission of a beta particle from the nucleus of an atom
Gamma radiation, unlike alpha or beta, does not consist of any particles, instead consisting of a photon of energy being emitted from an unstable nucleus.
Gamma radiation is sometimes considered to be the second phase of a nuclear decay. Once a nucleus has gone through either an alpha or beta decay, the nucleus can be in an 'excited state' similar to an electron in an excited state / energy level. The de-excitation of the nucleus results in the production of gamma radiation.
Having no mass or charge, gamma radiation can travel much farther through air than alpha or beta, losing (on average) half its energy for every 500 feet. Gamma waves can be stopped by a thick or dense enough layer material, with high atomic number materials such as lead or depleted uranium being the most effective form of shielding.
Gamma radiation: The emission of an high-energy wave from the nucleus of an atom
Attenuation Range (Penetration Range)
Attenuation Range (Penetration Range)
Attenuation rate (the gradual loss of flux intensity through a medium), the penetration or range of radiation depends on its energy, the material it encounters, and the type of radiation. (a) Greater energy means greater range. (b) Radiation has a smaller range in materials with high electron density. (c) Alphas have the smallest range, betas have a greater range, and gammas penetrate the farthest. OpenStax - C. 31.1
Cloud Chamber Visualization
Cloud Chamber Visualization
What is the primary function of a cloud chamber in physics experiments?
To measure the temperature of gases
To observe the trajectory of radioactive particles
To calculate the speed of sound in different mediums
To study the behavior of light waves
Which type of radiation is most easily observed in a cloud chamber?
Alpha particles
Beta particles
Gamma rays
X-raysd
In a cloud chamber, the trails left by alpha particles are typically:
Straight and long
Zigzag and short
Straight and short
Curved and long
Why is alcohol vapor often used in a cloud chamber?**
To create a conductive medium
To enhance the visibility of particle tracks
To maintain a constant temperature
To generate a magnetic field
When a Helmholtz coil is used to create a uniform magnetic field around a cloud chamber, how does this affect the observation of charged particles, and what can be inferred about these particles?
The magnetic field has no effect on the particle trajectories; thus, no additional information can be inferred.
The charged particles move in straight lines, indicating their mass and charge.
The charged particles follow curved paths, and the curvature can be used to determine their charge-to-mass ratio.
The magnetic field causes the particles to accelerate, allowing for the measurement of their velocity.
Explain how a cloud chamber works and why it is an effective tool for observing radioactive decay.
Discuss the historical significance and modern relevance of cloud chambers in the field of particle physics. How have cloud chambers contributed to our understanding of atomic and subatomic particles, and what are their limitations compared to more modern particle detectors?
Based on the observations made in a cloud chamber, how can one determine the energy levels of different types of radiation? Consider the length, thickness, and shape of the trails in your explanation.
Image 1: Compare the relative velocities, masses and charges of the particles that created the red and blue tracks.
In all the bubble chamber images, the particles enter the chamber from the left, and the magnetic field points out of the page.
Image 2: Compare the relative velocities, masses and charges of the particles that created tracks 1, 2, and 3.
Making alpha particles visible
Making alpha particles visible
How to build your own particle detector
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