1. IV. Isotopes
2 or more atoms of the same element having the same number of protons BUT different numbers of neutrons

2. How does altering the neutron number affect the properties of an atom?
It changes its mass!

3. Because elements naturally have different isotopes, the atomic mass shown on the periodic table is an average of all known isotopes.
This explains why the average is typically a decimal.

4. B. Illustrating Isotopes
          
       
                  
                
Deuterium
Tritium
Hydrogen
Commonly shown with just atomic mass #
Ex. Hydrogen - 2
Ex. Boron – 10
Ex. Boron - 11
AZX
A= atomic mass #
Z= atomic #
X= element symbol

5. How could you illustrate an atom of Uranium?
2. How could you illustrate an atom of sodium that has lost one neutron?
3. How could you illustrate an atom of carbon that has gained two neutrons?

6. C. Types of Isotopes
Stable: the nucleus contains enough neutrons to block the repulsive forces of the protons. This keeps the isotope from breaking down over time.
2. Unstable: the nucleus of the atom does not have right amount of neutrons to block the repulsive forces of the protons; this makes the isotope radioactive!

7. D. Radioactive Isotopes
Radioactive isotopes have unstable nuclei and undergo nuclear decay (breakdown)
2. Nuclear decay involves the emission of energy and/or particles from the nucleus in an attempt to become more stable.
3. The energy/particles emitted from the nucleus are termed radiation and can be alpha or beta particles and gamma rays.

8. 4. Isotopes disintegrate at predictable rates, so they are useful for determining age/measuring time. (C-14)
5. Because most elements have unstable isotopes, there is radiation present in almost every environment.