1. Unit 2 Part 2: Nuclear Chemistry
1st, 3rd, and 4th Periods

2. Nuclear Chemistry
Nuclear chemistry is the study of the structure of atomic nuclei and the changes they undergo.
Why would the nucleus want to undergo a change?
TO BECOME MORE STABLE & HAVE LESS ENERGY!!!

3. Radioactivity – The Beginning
In 1896, Antoine Becquerel and his graduate students, Marie and Pierre Curie, discover radioactivity
They used Uranium salts which were placed next to film plates. When opened, the plates were found to be developed.

4. The Curies showed that uranium gave off rays that caused the plates to become exposed
Rays were called radioactivity
The three won a Nobel Prize for their work

5. This work was a deathblow to the theory of an indivisible atom
Relation to Dalton
This work was a deathblow to the theory of an indivisible atom
Radioactive isotopes have unstable nuclei that overtime transform to a stable non- radioactive nucleus

6. Three types of radiation are produced: alpha, beta and gamma particles
Radioactive Decay
Radioactive Decay-process in which an unstable nucleus loses energy by emitting radiation
Three types of radiation are produced: alpha, beta and gamma particles

7. Alpha Radiation ()
Helium nuclei emitted from a radioactive source
Alpha particles- two protons and two neutrons; double positive charge
Written as 42He

8. Safety Concerns
Because of large mass and charge, these are not very penetrating
Can be stopped by a sheet of paper or even dead skin cells
Harmful if ingested

9. Alpha Particle
Loss of alpha particle lowers atomic number by two and mass number by four
Ex: Uranium-238 decays to Thorium- 234 and an alpha particle
238 92U  Th + 42He

10. Beta Radiation (  )
Formed by the decomposition of a neutron of an atom
10n  11H + 0–1e
Beta particles- fast moving electrons

11. Safety Concerns
Contain half the charge and are much lighter than alpha particle
Much more penetrating
Can be stopped by aluminum foil or thin pieces of wood

12. Beta Particles
Written as 0–1e or 0–1 
The proton stays in the nucleus and the electron is ejected from the atom
Ex: Carbon-14 decays to Nitrogen-14 and a beta particle
146C  147N + 0–1e

13. Gamma Radiation (  )
Electromagnetic (EM) Radiation
Visible light is also EM radiation, but at a much lower energy
Often emitted by the nuclei of disintegrating radioactive atoms along with alpha and beta radiation

14. Gamma Rays
No mass and no electrical charge
Does not alter atomic number or the mass number of an atom
This type of radiation only releases energy from the nucleus
Symbol:  (gamma)

15. X-Rays
X-Rays are NOT emitted during radioactive decay
Produced when excited electrons in certain metals lose their energy

16. Except for their origins, gamma and x- rays are essentially the same
Both rays pass easily through paper, wood, and the human body
Can be mostly stopped by several meters of concrete or several centimeters of lead

17. Positron: a positively charged electron; 0+1e or 0+1 Neutron: 10n0
Nuclear Equations
Other Particles:
Positron: a positively charged electron; 0+1e or 0+1
Neutron: 10n0
Proton: 11p+ or 11H+