1. Please take out your nuclear chemistry notes/ worksheet and turn to your three homework problems.
Please take out a sheet of notebook paper.
Nuclear equation quiz
Tomorrow! So listen good today
Ch 10 Nuclear Chemistry

2. Nucleus of the Atom Nuclei are made up of protons and neutrons.
Collectively called ‘nucleons’
In nuclear chemistry an atom is called a nuclide and referred to the number of mass number
Protons and neutrons are packed very closely together and contain the mass of the atom.

3. Fundamental forces in the nucleus
Strong nuclear: powerful force that holds protons and neutrons together
Weak Force: acts over a short range- radioactive decay
Electromagnetic force: attraction and repulsion of charged particles
Gravity: attractive force- acts between any two masses

4. Mass Defect
Most of the time the total number of protons, neutrons and electrons adds up to the total mass of the atom.
When the actual mass is different from the expected mass this is a mass defect.
This difference comes from Einsteins famous E=mc2 equation.
Some difference in mass comes from a conversion of mass to energy when a nucleus is created.

5. Radioactivity An unstable nucleus can emit radiation
charged particles
energy
All atoms with more than 83 protons are radioactive.
Almost all elements with more than 83 protons do not exist in nature and they decay rapidly soon after they are created.

6. Radioactive Decay: Nuclear Stability
Most stable ratio 1:1 protons: neutrons
Small elements- stable
Larger elements- less stable
radioactive

7. Nuclear Radiation – charged particles and energy (radiation)
Alpha Decay: + particle made of 2 protons and 2 neutrons
The same as a He atom.
Symbol: 
Symbol :42He
4 = mass # = p + n
2 = atomic # = p
Paper can block alpha particles- least penetrating
Heaviest form- loses energy as it moves

8. Alpha Decay of Uranium Uranium 238 undergoes Alpha decay:
It loses 2 protons and 4 amu (atomic mass)
To become Th-234
It loses one alpha particle which has the same number of protons and mass of the He-2 atom.

9. Beta Particles metal can block, faster and more penetrating than alpha
Negative radiation
An electron emitted by an unstable nucleus.
Symbol: 
Symbol: 0-1 e
A neutron decays into a proton & e-.
e- is emitted & proton remains trapped.
metal can block, faster and more penetrating than alpha

10. Gamma Decay Radiation with no mass & no charge. Ray of energy
Symbol: 
Atomic number and mass number remain the same but the nucleus loses energy.
Electromagnetic waves that travel at the speed of light.
Can pass through most metal, but most blocked by thick concrete

13. How do we measure radiation? Geiger Counter
Uses a gas filled tube to measure ionization radiation
If a radioactive particle penetrates the tube through which a high potential difference is applied.
This discharge is registered on the counter

14. Half-Life The time required for half of a radioisotope sample to decay
After 1 half life, half of the original sample is left and half has decayed into the daughter element
After 2 half-lives, only a quarter of the original sample still exists.

15. Half-lives can vary from fractions of seconds to billions of years.
Nuclear decay is constant and is not affected by varying conditions.
We can use
the 1/2 lives
to determine
the age of A
sample

16. Carbon Dating- Bones
Every plant and animal has Carbon in their body- you get it form the food you eat.
When an organism dies the carbon-14 levels will not go up.
The carbon-14 will decay into Nitrogen-14.
Scienctists use the ratio of Nitrogen to Carbon to determine how much of the original sample remains.
They know the half-life of Carbon-14 and can date the sample.

18. Quick-Lab: Modeling ½ Life p 300
Copy Purpose: Analyze data to calculate the “half-life” of a model radioactive element
Copy and answer hypothesis from board.
Procedure: Follow on page 300
You will get a zero if you eat anything in lab! I reuse the candy!
Instead of wallpaper squares we have candy hearts
Need to count out total hearts between partners- this is your starting “mass”
Work in groups of two
Roles: one counters & one recorder
Turn-In (Stapled together)
Purpose and hypothesis.
One data table AND GRAPH with groups results
Answers the Analyze and Conclude Q’s (Draw a chart)

19. Nuclear Fission
Splitting of atomic nuclei into 2 smaller nuclei of approx. equal mass.
U-235 undergoes fission
Not much energy is produced from one atom- only when a chain reaction occurs
Chain reactions are caused when the smaller parts collide into other nuclei and continue the process.
Chain reactions release huge quantities of ENERGY!

32. Examples of Nuclear Fission
Nuclear Weapons- release all energy at once

33. Ex: Nuclear Power Plants
Plants monitor controlled fission of U-235 to generate energy.
Energy heats water to make steam which turns the turbine of a generator
Steam condenses to liquid water which is re- used in the reactor core

34. Nuclear Fusion
Combining of two nuclei form a larger nucleus of larger mass
A lot of energy is released .
The sun is powered by fusion of Hydrogen to Helium
High temps are needed for fusion (10,000,000 °C).

36. Video-Field Trip- Nuclear Medicine
What is nuclear medicine?
If radioactive substances are used today to treat certain types of cancer, how was it possible for Marie Curie and Irene Curie to develop a form of cancer by working with radioactive substances?