Radioactivity

1
Radioactivity

• Chapter 9.1

2
(No Transcript)
3
(No Transcript)
4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
Nucleus
9
Strong Force

• 100 times stronger than the electrical force.
• Acts over a short range.

10
Strong Force

• Holds nucleus together by over coming the
  electrical force and keeping positively charged
  protons attracted to each other and to neutrons.
• The larger the nucleus the weaker the strong
  force.

11
Radioactivity

• In a large nucleus the strong force is too weak
  and the nucleus may decay and give off matter and
  energy due to the electrical force.

12
Radioactive Elements

• All nuclei above 83 p are radioactive.
• Almost all nuclei above 92 p are synthetic.

13
Atoms

• The number of p determines the atomic number and
  therefore the element.
• The number of p and n0 determines the atomic
  mass.

14
Stable Element
Atomic mass
C
12
Atomic
6
15
Isotopes

• Atoms of the same element ( of p) but varying
  numbers of n0.

16
Isotope examples

• Helium-3 and Helium-4
• Carbon-13 and Carbon-14

17
Nuclear Decay

• Chapter 9.2

18
Decay

• When a nucleus decays, particles and energy are
  emitted (released).
• 3 types
• Alpha Beta Gamma

19
Alpha Particle

• Made from 2 p and 2 n0.
• Lose energy quickly, therefore less penetrating.

20
Alpha Particle
Symbol
?
Mass 4
Charge 2

21
Beta Particle

• n0 decays into a p and emits an e- (the emitted
  e- is called a beta particle).

22
Beta Particle
Symbol(s)
ß
-or-
Mass 0
Charge -1

23
Gamma Ray

• Most penetrating.
• Not particulate (no
  p, n0 or e- ).
• Type of electromagnetic wave.
• Usually released with an alpha or beta.

24
Gamma Ray

• Symbol ?
• Mass 0
• Charge 0

25
Half-life

• Measure of the amount of time required by a
  nuclei to decay by half.

26
Nuclear Reactions

• Chapter 9.4

27
Nuclear Fission

• Process of splitting a nucleus into two smaller
  nuclei with smaller masses.
• Only larger nuclei will do this.

28
Nuclear Fission
29
Nuclear Fusion

• To fuse means to put together.
• 2 nuclei with low masses are combined to form one
  larger nuclei.
• Releases more energy that Fission

30
Fusion on the Sun

• Only happens at very high temperatures (stars and
  sun millions of degrees Celsius). To get high
  kinetic energy.
• Hydrogen fuse together to make Helium