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RADIOACTIVITY
akmalcikmat
• Why certain nucleus is radioactive
• Radioactive process
• Half-life
• exponential decay curve
akmalcikmat
Understanding the term
• Radioactivity refers to the particles which are
emitted from nuclei as a result of nuclear
instab...
Stable and Unstable Atom /Nuclei
• Atoms found in nature are either stable or unstable. An atom is
stable if the forces am...
Why certain nucleus is radioactive?
• Unstable nuclei cause radioactivity.
• Radioactivity is caused by unstable nuclei tr...
Radioactive process
• In radioactive processes, particles or
electromagnetic radiation are emitted from the
nucleus. The m...
Conservation of Laws
• Law of conservation of energy
• Law of conservation of mass
• Law of conservation of electric charg...
Law of conservation of mass
• States that
the total energy (mass energy + kinetic energy +
energy in other form) remains u...
Law of conservation of mass number
• States that
The sum of mass numbers remains unchanged in
radioactive or nuclear proce...
Law of conservation of electric charge
• States that
The total charge during a radioactive process or
nuclear transformati...
Half life
• Definition : Time taken for the number of radioactive
nuclide to disintegrate to half its initial value
• Radi...
• We cannot predict exactly which atom will
decay at a certain time but we can estimate,
using the half-life, how many wil...
Graph : Number of radioactive nuclei against time
taken to become half of its initial value
The longer the half-life of a ...
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AS Level Physics' Radioactivity Presentation

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AS Level Physics' Radioactivity group presentation in class.
covers up the question on:
-Why certain nucleus is radioactive
-Radioactive process
-Half-life
-exponential decay curve
with a very lil' detail explanation for each subtopic.

Published in: Education
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AS Level Physics' Radioactivity Presentation

  1. 1. RADIOACTIVITY akmalcikmat
  2. 2. • Why certain nucleus is radioactive • Radioactive process • Half-life • exponential decay curve akmalcikmat
  3. 3. Understanding the term • Radioactivity refers to the particles which are emitted from nuclei as a result of nuclear instability • Radiation is energy given off by some atoms in the form of particles or rays akmalcikmat
  4. 4. Stable and Unstable Atom /Nuclei • Atoms found in nature are either stable or unstable. An atom is stable if the forces among the particles that make up the nucleus are balanced. • An atom is said to be unstable (radioactive) if these forces are unbalanced, the nucleus is said to has an excess of internal energy • Unstable atoms are called radionuclides. The instability of a radionuclide’s nucleus may result from an excess of either neutrons or protons • The protons in a nucleus are all positively charged and so they repel each other. This should push the protons apart but it doesn’t so there must be another force which keeps the nucleus together. The force is called the STRONG NUCLEAR FORCE akmalcikmat
  5. 5. Why certain nucleus is radioactive? • Unstable nuclei cause radioactivity. • Radioactivity is caused by unstable nuclei trying to become stable by emitting particles and/or energy . • The nuclei of radioactive substances are unstable due to an unstable ratio of protons to neutrons. • In stable atoms of relatively low atomic mass there are approximately equal numbers of protons and neutrons i.e. a proton to neutrons ratio of about 1:1. • In stable atoms of higher atomic mass more neutrons than protons are needed to keep the nucleus stable. akmalcikmat
  6. 6. Radioactive process • In radioactive processes, particles or electromagnetic radiation are emitted from the nucleus. The most common forms of radiation emitted have been traditionally classified as alpha, beta and gamma radiation • During the processes, a radionuclide tries to attain stability • Nuclear radiation occurs in other forms, including the emission of protons or neutrons or spontaneous fission of a massive nucleus akmalcikmat
  7. 7. Conservation of Laws • Law of conservation of energy • Law of conservation of mass • Law of conservation of electric charge akmalcikmat
  8. 8. Law of conservation of mass • States that the total energy (mass energy + kinetic energy + energy in other form) remains unchanged during a radioactive process or nuclear transformation akmalcikmat
  9. 9. Law of conservation of mass number • States that The sum of mass numbers remains unchanged in radioactive or nuclear processes • The mass number of a neutron or proton is assumed to be one and that of an electron zero akmalcikmat
  10. 10. Law of conservation of electric charge • States that The total charge during a radioactive process or nuclear transformation remains unchanged akmalcikmat
  11. 11. Half life • Definition : Time taken for the number of radioactive nuclide to disintegrate to half its initial value • Radioactive substances will give out radiation all the time, regardless of what happens to them physically or chemically. As they decay the atoms change to daughter atoms, until eventually there won't be any of the original atoms left. • Different substances decay at different rates and so will last for different lengths of time. We use the half-life of a substance to tell us which substances decay the quickest. It is also the time it takes for the count-rate of a substance to reduce to half of the original value. akmalcikmat
  12. 12. • We cannot predict exactly which atom will decay at a certain time but we can estimate, using the half-life, how many will decay over a period of time. • The half-life of a substance can be found by measuring the count-rate of the substance with a Geiger-Muller tube over a period of time. By plotting a graph of count-rate against time the half-life can be seen on the graph. akmalcikmat
  13. 13. Graph : Number of radioactive nuclei against time taken to become half of its initial value The longer the half-life of a substance the slower the substance will decay and the less radiation it will emit in a certain length of time. akmalcikmat

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