Nuclear Reactions

Explain isotope stability

• The stability of an isotope is dependent on the ration of protons and neutrons in the nucleus

• if the ratio does not lie in the belt of stability, the nucleus can undergo spontaneous radioactive decay

• An atom will usually go through a series of radioactive decay on its way to stability

• each step in the decay process takes a different length of time and different atoms within a sample will break down at different times

What is Half-life?

The time it takes for half of the sample to decay

• time passed/ half life = n

• mass remaining = initial mass*(1/2)ⁿ

What is radioactive decay?

• the spontaneous natural process where an unstable atomic nucleus loses energy by emitting particles or waves, called ionizing radiation, to reach a more stable state

What are the 5 types of radioactive decay?

alpha decay, beta decay, gamma decay, positron emission, and electron capture

What is alpha decay?

• the spontaneous emission of a helium nucleus from an atom

  • e.g. ²²⁶Ra → ²²²Rn + ⁴He

• alpha particles are easily blocked by a sheet of paper, but readily damage chromosomes if inhaled or ingested

What is beta decay?

• a neutron is converted into a proton and a beta particle (an electron created within the nucleus but otherwise indistinguishable from an orbital electron)

  • ¹⁴C →¹⁴N + _-1β

What is gamma decay? 

• a gamma particle is a high energy photon which is emitted when the nucleus is in an excited state. (this is similar to the X-rays produced in non-nuclear electron-atom interactions)

• Gamma rays are often given off after other nuclear reactions

• Gamma rays are often dangerous because it is hard to block them, but this also makes them useful for medical diagnostics

What is a positron emission? 

• a proton is converted into a neutron and positron (