1. The Nucleus Objectives:
Relate nuclear stability to the ratio of neutrons to protons
Describe the forms of radioactive decay
Balance decay equations

2. The Nucleus Definitions: nucleons-protons and neutrons collectively
nuclide- a specific atom (in nuclear chemistry)
mass defect – difference between the actual mass of an atom and the sum of the masses of all of an atom’s protons, neutrons, and electrons
Nuclear binding energy – energy released when a nucleus is formed from nucleons (E = mc2)

3. Binding Energy per Nucleon
Higher binding energy/nucleon  higher nuclear stability

4. Band of Stability Small atoms tend to have neutron-proton ratios ~ 1:1
The ratio approaches 1.5:1 as the atomic number increases
Explained by the relationship between strong nuclear forces and electrostatic repulsion

5. Nucleons and nuclear stability
Strong nuclear forces act over very short distances
As the # of protons increases, the electrostatic force between protons increases
More neutrons are needed to stabilize the nucleus

6. Nuclear Reactions
Transmutation – transformation of one element into another
Nuclear reactions occur when unstable nuclei undergo changes in the # of protons and neutrons in order to increase stability
Large amounts of energy are given off

7. Nuclear Reactions
In nuclear equations, the sum of atomic #’s and mass #’s must be equal on both sides of the equation.

8. Complete the following nuclear reactions: