LECTURE 10.4

1
LECTURE 10.4 RADIOACTIVE DECAY
2
Todays Learning Targets

• LT 9.3 I can compare and contrast normal
  isotopes and radioactive isotopes. I can discuss
  the three forms of decay that radioactive
  isotopes can undergo and how the nucleus is
  altered in each type of decay.
• LT 9.4 I can list the three different type of
  radiation and the impact that each one of these
  types of decay can have on myself and other
  living matter

3
What is radioactive decay?
4
I. Radioactive Decay

• Atoms can be unstable and breakdown
• Radioactive Decay The spontaneous breakdown of
  the nucleus into a smaller nucleus, accompanied
  by the release of particles, radiation, or both.

5
What are the 3 types of radioactive decay?
6
I. Alpha (a) Decay

• Alpha Decay When an atom splits its nucleus
  into
• A smaller nucleus and
• A Helium atom (2 protons, 2 neutrons).
• Observed often in very heavy atoms
• Alpha particles on travel a few cm in air
• Paper blocks alpha particles

7
(No Transcript)
8
Alpha Radiation
9
II. Beta (ß) Decay

• Some elements are unstable because their proton
  to neutron ratio is too large.
• Beta decay converts neutrons to protons and
  releases an electron known as a beta particle
• neutron ? proton ß
• Travel a few meters in the air
• Metals provide a shield against beta radiation.

Electron
10
(No Transcript)
11
Beta Radiation
12
III. Gamma (?) Decay

• Gamma rays are high energy waves that are
  released when nucleus goes from high energy state
  to low energy.
• Gamma radiation is the most dangerous. It can
  lead to DNA mutations and cancers.
• Gamma radiation requires thick pieces of
  lead/concrete in order to stop.

13
(No Transcript)
14
Gamma Radiation
15
Radiation Summary
Type of Radiation Description Blocked by?
Alpha (a)
Beta (ß)
Gamma (?)
The spitting of a nucleus into a smaller nucleus
and a He atom (alpha particle
Blocked by paper
Converts a neutron to a proton and an electron
(beta particle)
Blocked by metals
High energy waves that are released by nucleus
Blocked by lead
16
Class Example

• Label the following decay as alpha, beta or gamma
  decay
• 4319K ? 4320Ca electron

17
Table Talk

• Label the following decay as alpha, beta or gamma
  decay
• 21084Po ? 20682Pb 42He

18
Table Talk

• Complete the following reaction if it undergoes
  beta decay
• 147N ? ______ _______