1. Nuclear Chemistry EQ: How does Nuclear chemistry affect the structure of atomic nuclei?
Ch 25 CVHS

2. Why do atoms emit radiation?
The nucleus is unstable due in part to the ratio of protons and neutrons
Atoms that emit particles are radioisotopes
Atoms emit radiation & lose energy = more stable

3. Types of Radiation
Alpha (α): Positive particle bends toward neg. plate
Beta (β): Neg. charge, bend toward positive, less massive than alpha so they bend more
Gamma (γ): Not charged don’t bend

4. Alpha Particle Same as a He nucleus 2+ charge, b/c of 2 protons
Alpha radiation: stream of alpha particles
Large, slow moving, stopped by a sheet of paper
After the decay, the atom is no longer Radium WHY?
Different # of protons, it is now radon Ra
Atomic # & Mass # must be equal on both sides.

5. Beta Radiation Mass # stays the same Atomic # increases by 1
Fast moving electron
Emitted from neutron of unstable nucleus
Light weight, fast moving
Aluminum foil stops them
Negative charge
Notice that the # of protons in the nucleus increases by 1, so a new element is formed
A neutron splits, the proton stays in the nucleus and the high energy electron (beta particle) leaves
Mass # stays the same
Atomic # increases by 1

6. Gamma Radiation
High Energy, short wavelength, electromagnetic radiation
No mass & no charge
Energy that accompanies alpha & Beta radiation
Gamma symbols are typically omitted from nuclear equations b/c they have no impact on mass or charge

7. Nuclear Stability
Protons repel eachother b/c they are positively charged.
Small Effect: Ratio of Protons to neutrons
For atoms with low atomic numbers (< 20), the most stable nuclei are those with neutron-to-proton ratios of 1 : 1, Neutron to proton ratio increases to a max of 1.5 : 1; all atoms above 83 Bi are radioactive
STRONG NUCLEAR FORCE : a force that overcomes the electrostatic repulsion of the positively charged protons
Acts only on subatomic particles

8. Balancing Nuclear Equation Practice
Write a balanced nuclear equation for the alpha decay of thorium-230
Reactant: Thorium 230, products: X & alpha particle
Make sure that the atomic numbers and masses are equal on both sides of the equation: Law of Conservation of Mass then look up the new element formed by it’s atomic number (protons) on the periodic table.
Notice: = and 90 = so mass is conserved

9. Beta Decay Practice
What element is formed when undergoes beta decay? Give the atomic number and mass number of the element.
 X +
What is X? It has to have an atomic number that equals 26 when we subtract 1.
Atomic # 27 is Cobalt. 
Write a balanced nuclear equation for the beta decay of the following radioisotope

10. Half Life
A half-life is the time required for one-half of a radioisotope’s nuclei to decay into its products
strontium-90 Half Life = 29
10.0 g today = 5.0 g in 29 years

11. Calculating a half life
Where t is the elapsed time and T is the duration of the half-life, must be in the same units.

12. Practice The half-life of iron-59 is 44.5 days.
How much of a mg sample will remain after days?
Divide time passed by duration of half life
133.5/44.5 = 3
3 half lives have passed
Divide 2 in half 3 times
2/2=1
1/2= .5
.5/2=.25
.25 g remain after days
Substitute the values for n and initial mass into the exponential decay equation and solve

13. C 14 Dating

14. Nuclear Fission Splitting of nucleus into fragments Large atoms
Releases large amt of energy
Critical mass creates a chain reaction
Nuclear power plants harness the energy released by fission reactions
Heat generates steam
Steam powers turbines to generate electricity
Cadmium and Boron rods keep the reaction under control by absorbing the atomic particles that are released

15. Nuclear Fusion Combining of atomic nuclei Occurs on the sun
Thermonuclear reactions
Release a large amt of energy but happen at very HIGH temperatures
Occurs on the sun
Scientists use to create new atoms