7 Radioactivity and Particles – Part B “Radioactivity”

Syllabus Aims…

7.2 describe the structure of an atom in terms of protons, neutrons and electrons and use symbols such as C14 to describe particular nuclei

7.3 know the terms atomic (proton) number, mass (nucleon) number and isotope

7.4 know that alpha (a) particles, beta ( b-) particles and gamma (g) rays are ionising radiations emitted from unstable nuclei in a random process

7.5 describe the nature of alpha (a) particles, beta ( b-) particles and gamma (g) rays and recall that they may be distinguished in terms of penetrating power and ability to ionise

7.6 practical: investigate the penetration powers of different types of radiation using either radioactive sources or simulations.

7.7 describe the effects on the atomic and mass numbers of a nucleus of the emission of each of the four main types of radiation (alpha, beta, gamma and neutron radiation)

7.8 understand how to complete balanced nuclear equations in terms of mass and charge
7.9 know that photographic film or a Geiger–Müller detector can detect ionising radiations
7.10 explain the sources of background (ionising) radiation from Earth and space.

7.11 know that the activity of a radioactive source decreases over a period of time and is measured in becquerels

7.12 know the term ‘half-life’ and understand that it is different for different radioactive isotopes

7.13 use the concept of the half-life to carry out simple calculations on activity, including graphical methods.

7.14 describe the uses of radioactivity in industry and medicine

7.15 describe the difference between contamination and irradiation
7.16 describe the dangers of ionising radiations including

that radiation can cause mutations in living organisms
that radiation can damage cells and tissue
the problems arising in the disposal of radioactive waste and how the associated risks can be reduced.

Resources…

Use this PowerPoint for a quick review…

7B Radioactivity and Particles Lessons 6 to 9

7B Radioactivity and Particles Lessons 1 to 5

Cloud Chambers Alpha Particles Polonium Sources and Cosmic Rays - A Level Physics

Using a thoriated welding rod OR polonium 2010 source in a cloud chamber is a popular way to visualize alpha (and beta) radiation; the thorium (as thorium oxide) decays, emitting ...energetic particles that ionize alcohol vapor, creating visible, short, thick trails (alpha) or longer, wispy ones (beta) against a dark background, demonstrating nuclear decay and particle shielding (like paper stopping alphas).

The Source: Thoriated tungsten electrodes (often red-coded) contain thorium-232, a naturally radioactive element that undergoes alpha and beta decay in its decay chain.

The Chamber: A cooled chamber with super-saturated alcohol vapor (or other solvent) creates a sensitive environment.

Particle Trails:

Alpha Particles: Heavy, slow, short-range. They leave thick, straight, bright trails of condensed droplets, usually only a few centimeters long.
Beta Particles: Lighter, faster, longer-range. They produce thinner, more erratic, wispy trails.

Visualization: A bright light source illuminates the trails, making the condensation visible.

Key Observations:

Alpha Tracks: Short, dense, straight lines.

Shielding: Covering the rod with paper will stop the alpha tracks, but the longer beta tracks (if any) might still be seen, showing alpha particles' low penetration.

Thorium Decay Chain: You'll see tracks from alpha and beta decays as the thorium-232 decays through its daughter products, including radon gas and its descendants.
Safety & Setup Tips

Safety: Thorium is a low-level radioactive material, so handle with care and follow safety guidelines (e.g., don't grind the rods).

Setup: Use a dark, sealed container, a cold plate (dry ice or Peltier cooler), felt soaked in isopropyl alcohol, and a bright LED light.

Patience: Allow the chamber to cool and the vapor to saturate for several minutes before observing.Show More

Cloud Chambers Alpha Particles Polonium Sources and Cosmic Rays - A Level Physics

Gebelein Man - The Oldest Egypt Mummy in the World - British Museum

Gebelein, Egypt, Predynastic period, around 3500 BC

A naturally preserved mummy in a reconstructed pit-grave.

This man died more than five thousand years ago and was buried at the site of Gebelein, ...in Upper Egypt. The reconstruction of his grave illustrates the early Egyptian custom of placing the body in a contracted, foetal position, usually on the left side, with the head to the south, facing the west, the land of the dead where he would be reborn. Around him were all the things he might need for his afterlife, especially pottery to hold and serve food.

In the Predynastic period (4400-3100 BC), the time before the pharaohs, the dead were buried in shallow graves cut into the desert sand. The graves were often lined with reed mats, making them like a bed, and the body was covered with linen or skins and more mats, like a blanket, before the grave was refilled and perhaps topped by a mound of dirt. Contact with the hot dry sand naturally preserved the bodies because the sand absorbed the water that constitutes approximately 75% by weight of the human body. Bacteria cannot breed without moisture and as a result, the bodies frequently did not decay, but simply dried out. The body of this man is remarkably well-preserved, even down to his finger-nails and hair, which has probably faded with time.

Chance discoveries of these sand-dried mummies (for example, when a grave was disturbed by animals or robbers), may have promoted the belief that physical preservation of the body was necessary for the afterlife. This may have led the later Egyptians to develop means of artificial mummification after the introduction of coffins and deeper graves separated the body from the natural drying effects of the sand.

The objects that surrounded Gebelein Man in his original burial are unknown. On display is a selection of typical grave-goods from other graves of the middle Predynastic period (about 3500 BC), the time we believe he died. Attempts to date the body using Carbon 14 (the radiocarbon method) have so far been unsuccessful

The AI intro part to my video is made using Veo 3.1 and had this script if you are interested in AI generated content.

**Scene:** A prehistoric mummy, previously interred, awakens in a sudden, agonizing moment, struggling to sit up and revealing a silent scream.
**Visuals:** Dramatic, high-contrast rim lighting catches the desiccated, reddish-brown skin of the mummy as it lies in the coarse sand and grave goods. The lighting emphasizes the texture of the dry body and the cracked white bone fragments on its head. Slowly, its dark, preserved hand—which had rested near its cheek—pulls away from its face. As the hand withdraws, the desiccated jaw opens unnaturally wide, revealing its dark teeth in a silent, elongated howl of agony. The scene is rich with archaeological detail: fragmented pottery, including a smooth black and terracotta piece, and a small jug, are sharply lit but fall into deep shadow, underscoring the ancient, unsettling setting.

**Camera:** A slow, creeping dolly zoom pulls backward and slightly upward. Shot on an anamorphic lens with a very shallow depth of field, the focus is locked tightly on the mummy's face and moving hand, creating oval bokeh in the background highlights. The camera continues to pull back as the mummy’s torso strains and lifts from the sand, transitioning from a prone to a sitting position.Show More