• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Radioactivity notes

Extracts from this document...





The atomic number of an atom is the number of protons in the nucleus.

The mass number of an atom is the total number of protons and neutrons in the nucleus.

The atoms of an element have the same number of protons in their nuclei but the number of neutrons can vary.

Atoms with the same number of protons but different numbers of neutrons are called isotopes.

An atom is radioactive if its nucleus has an unstable proton to neutron ratio.

An unstable proton to neutron ratio causes an elevated energy level in the nucleus.

When a nucleus undergoes radioactive decay it lowers its energy level by giving off radiation.

The radiation given off by atoms that are naturally radioactive can be either alpha particles, beta particles or gamma rays.

Alpha particles are helium nuclei - two protons and two neutrons.

When an alpha particle is released, a new nucleus is formed with two less protons and two less neutrons.

Beta particles are electrons formed when a neutron in the nucleus changes to a proton and an electron.

...read more.


The number of nuclei remaining in unstable form after time t is equal to the number when timing started times e to the power minus the decay constant times t.



Doses are measured by determining the number of joules of energy absorbed per kg of the body by radiation that has been absorbed.

If ionizing radiation transfers 1 Joule of energy to 1 kg of body tissue, the Absorbed Dose is 1 Gray.

Doses are usually around millionths of Grays.

The amount of damage to the body depends on the type of radiation.

The Absorbed Dose Equivalent equals the Absorbed Dose in Gray times the Quality Factor of the radiation absorbed. e.g.  particles  x 20         particles  x 1

The unit of Absorbed Dose Equivalent is called the Sievert Sv.

1,000,000Sv                Nausea, vomiting, not lethal but cancers likely in future years.

5,000,000Sv                Serious illness and 50% chance of imminent death.

10,000,000Sv        All people die.

Organs vary in the way they are affected by ionizing radiations. Each organ has a risk factor.

The Effective Absorbed Dose Equivalent an organ receives equals the Absorbed Dose Equivalent times the Risk Factor of the organ. e.g. bones  x 0.03 lungs  x 0.12

Nuclear Transformations

...read more.



Nuclear Force

The nuclear force of attraction is the same for proton/proton, neutron/neutron and neutron/proton combinations.

The force acts over very short distances. A particle in the nucleus is only attracted to its immediate neighbours.

The nuclear force is about 100 times stronger than the repulsion between protons at the same distance apart, and holds the nucleus together.


Fusion is the joining together of the isotopes of hydrogen called deuterium 2H1 and tritium 3H1.

A deuterium nucleus has one proton and one neutron. A tritium nucleus has one proton and two neutrons.

The fusion reaction is 2H1 plus  3H1  gives 4He2  plus  1n0 .

More energy is released in this process than in the fission process because more mass is lost.

To get the deuterium and the tritium nuclei to stick together, the nuclei must come very close so the nuclear force overcomes the repulsion between the protons.

The nuclei must be moving very fast if they are to get close enough to stick together and this means the temperature has to be as high as in the sun.

In the fusion reactors being developed, the super high temperature gas is held away from the walls of the container by a very strong magnetic field.

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Mechanics & Radioactivity section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Mechanics & Radioactivity essays

  1. Peer reviewed

    Are mobile phones a health risk?

    4 star(s)

    is thought to be more of a risk in children, who have thinner skulls and a still-developing nervous system [4]. Physiological Effects of EM Radiation Effects of Low-Frequency (Non-Ionizing) EM Radiation In General It is important to remember that Mobile Phones utilise Microwave radiation, a non-ionizing form of radiation, so

  2. Use of technology in a hospital radiology department. The department of imaging is one ...

    Surgeons are conducting techniques which could revaluations the lives of man how undergoing treatment for prostate cancer, a probe inserted in the back passage, emit sound wave to destroy cancerous tissue, the research group are hoping this will reduce side effect, such as impotence and incontinence.

  1. Multi-bladed Pumps. Does the number of propellor blades affect the efficiency of a ...

    At this frequency, the time between flashes of the strobe and the time for one blade of the propeller to reach the former position of the blade before it is equal. If you find the angle in radians (?) between two adjacent blades and multiply it by the frequency (f)

  2. Physics a Nuclear Bomb

    These ejected electrons are called the beta particles. 1, 7 To understand the immense power withheld in Atomic bombs such as Little boy and Fat boy the best place to look is at Einstein's relationship between Mass and Energy E=MC2, where E=Energy (J), M=Mass (Kg), and C=the speed of light (m/s).

  1. Free essay

    CIRCULAR MOTION - revision notes and calculations

    The centripetal force changes only the direction of the motion but not it's magnitude, therefore, the speed V is constant. (d) (1) One student holds the glass tube vertically and whirls the bung around above his head, and the speed of the bung is increased until the marker is just below the tube.

  2. Mechanics notes

    The total momentum of a system is the same, before and after any interaction. The impulse an object receives equals the force acting on the object times the time it lasts. The impulse an object receives equals its change in momentum.

  1. The Physics of an Atomic Bomb

    The slow fissionable isotopes have high neutron fission cross-sections for neutrons of all energies, while having low cross-sections for absorption. Fast fissionable isotopes have zero fission cross-sections below a certain point (1 MeV for U-238), but the cross-sections climb quickly above the point.

  2. Explain how excessive exposure to radiation can cause harm.

    Time, distance, shielding, and substitution represent four practical methods laboratory personnel can use to minimize external radiation exposure. Time The dose of radiation received is directly proportional to the amount of time spent in a radiation field. Thus, reducing the time by one-half will reduce the radiation dose by one-half.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work