NUCLEAR CHEMISTRYStudying Radioactivity

CLASSROOM NOTESHistory of Radiation (not testable but fun )

INTRODUCTION TO NUCLEAR CHEMISTRY Wilhelm Conrad Roentgen

studied cathode ray tubes and the light they produced in 1895.

While researching, he had a vial of barium platinocyanide crystals by his desk which fluoresced near the cathode ray tube.

When he placed the crystals in a box, away from the cathode ray tube, the still emitted light.

DISCOVERY OF X-RAYS

Roentgen asked his wife to place her hand on a photographic plate and exposed it to rays from the tube. When he developed the plate he saw the shadows of her bones and ring she was wearing. After some more experiments Roentgen named the rays “x-rays”.

X-RAYS Within 3 months

DIY x-ray machines were marketed and the rich and famous were constantly photographing their bones with jewelry on.

X-RAYSSoon x-rays

were a piece of art. In this photo a shoemaker placed his foot in the machine to see what it looked like and came up with an idea:

X-RAYSThe shoe fitting

machine was invented in the late 1940s but banned in the 1970s because of the leakage of radiation to the environment.

X-RAYSThe danger of

x-rays were later understood when people became over exposed to x-rays as shown here.

RADIOACTIVE MINERALSAntoine Henry

Becquerel discovered the radioactivity of Uranium in the early 1900s.

RADIOACTIVE MINERALS After many women

who worked in the watch factory became ill it was apparent that they had something in common.

They were painting with radium, which Marie Curie and her husband discovered in 1898.

RADIATION Since then there

have been many developments made with radiation including nuclear power, nuclear medicine, warfare, etc.

RADIOACTIVE DECAYThe process by which nuclei emit particles and change into new elements.

REVIEW:1. Isotopes of the same element have

the same number of _________ but differ in their number of ___________, which results in different __________.

2. Write the isotopic notation for C-12 and C-14. Explain their similarities and differences.

3. What does “radioactive” mean? 4. Which elements on the periodic table

have no stable isotopes?

ATOMIC NOTATION:

Subtract atomic number from mass number to find the ________________Number of neutrons

RADIOACTIVITY Sometimes an atom is

unstable and will decay into a new atom. This type of atom is radioactive.

This is due to the proton-neutron ratio. The band of stability refers to atoms that are stable due to stable proton-neutron ratios.

RADIOACTIVITY Atoms above the

belt have too many neutrons and beta decay due to this.

The beta particle is an electron created when a neutron decays.

I13153 Xe131

54 + e0−1

0

−1 e0−1or

RADIOACTIVITY Atoms below this

belt have too many protons and positron decay.

The positron is the opposite of a beta particle.C11

6 B115 + e0

1

ALPHA DECAY

Atoms with 82 or more protons alpha decay. Alpha particles are weak due to their mass. Alpha particles are the helium nuclei. What is the difference between alpha and

helium particles?

U23892 Th234

90 He42+

GAMMA DECAY

Strongest particle. Accompanies most decay. Usually not written due to the fact that it

cannot change the mass or charge of any of the species.

00

PENETRATING POWER

RADIATION IS CHARGED

- - - - - - - - - - - - - - - - - - - -

+ + + + + + + + + + + + + + + +

Radioactive source

INTERESTING FACTS:Atoms with even atomic and

mass numbers are usually more stable.

Magic numbers 2, 8, 20, 28, 50, 82 and 126 represent atomic and mass numbers that are amazingly stable.

TRANSMUTATION So far we have studied natural transmutation,

which have reactions that have one reactant breaking down. All “decay” is natural.

Artificial transmutation involves a high speed particle bombarding the nucleus. This occurs in particle accelerators.

Answer the questions in the nuclear packet on

pages 1 and 2.

MORE CLASSROOM NOTES

Again not testable but interesting. Take pride in your hometown!

PARTICLE ACCELERATORSThe particle accelerator at CERN in Geneva (France).

BROOKHAVEN NATIONAL LABORATORY

“RHIC” or the “Relativistic Heavy Ion collider” is only miles away and is world renowned.

CAMP UPTON Named after Emory

Upton, a union general during the civil war.

Camp Upton was used to house up to 40,000 soldiers and train them for the United States from 1917 to 1921.

CAMP UPTON Sergeant Irving

Berlin (song writer known for “Yip Yip Yaphank” and “Oh How I Hate to Get up in the Morning”) became famous after training at Camp Upton.

CAMP UPTON

Later, in 1940 it was used again before WWII as an induction center which inducted Sidney Poitier.

CAMP UPTON After the war, the facility changed to a hospital

and rehabilitation center in September 1944. In January 1947 it was converted to the lab in

order to study the “peaceful” uses of the atom.

BNL Some of the

structures from the camp were moved to Cherry Grove on Fire Island.

It is now over 5000 acres of ecological area in the Pine Barrens of which 1000 are occupied by BNL buildings.

TRANSMUTATIONFission and Fusion

TRANSMUTATIONIf you add the actual masses of all the protons,

neutrons and electrons in an atom and compare it to the atom’s actual mass, mass is lost. This is known as mass deficit. Mass is converted to energy!

The energy holds the subatomic particles together and is called the binding energy.

When these reactions occur, small amounts of mass can be created into LARGE amounts of energy.

This energy can be harvested in fission and fusion reactors for everyday energy use.

Nuclear energy is much more powerful than any other source of energy known. What are some of the benefits and risks of using nuclear energy?

EXAMPLES Write the decay equation for Pu-239 and In-

120. Fill in the blanks:

1. 3717Cl + 1

1H ___2. 11

5B + 42He ____ + 1

0n3. _____ + 2

1H 6128 Ni + 4

2He

3818Ar

147N

6329Cu

FISSIONA neutron is shot at a radioactive source which splits producing energy.

FISSIONThis creates a chain reaction that must be controlled! The only way it will stop is if the radioactive source dies out. Therefore, many reactors only use a critical mass, which is the mass needed for a specific amount of energy made.

FISSION REACTORSThe reaction’s energy is converted to steam which turns and turbine system, creating electrical energy from nuclear energy.

FISSION REACTORSFuel rods contain the fissionable radioactive source.

Control rods can regulate the neutrons absorbed.

Cooling Fluid acts as a moderator, slowing neutrons down.

FISSION The fission

reaction produces radioactive waste that must be stored.

Currently the waste is placed in large lead boxes under ground around the country.

YUCCA MOUNTAIN The Yucca Mountain,

in Nevada, is a large long term storage facility for nuclear waste and testing.

LOVE CANAL: CANADA In the late 1970s it

was discovered that slow leakage of lead boxes containing radioactive waste caused birth defects and nervous disorders.

Water and plants were contaminated. Many people chose to relocate, though some still live at that site today.

FUSION Fusion is a better reaction to use since it harvests moreenergy, with less waste and less danger (no chain reactions). However, fusion is too expensive. Tokamak apparati like the one shown at theright show promise for carrying out these

reactions.They use magnetic fields to heat the material.

FUSION 11H + 3

1H 42HE + ENERGY

Answer the questions in the nuclear packet page 3.

BENEFITS AND RISKS

BENEFITS AND RISKSBrainstorm benefits and risks of

using radioactivity for a class discussion.

MEASURING RADIOACTIVITY One can use a device

like this Geiger counter to measure the amount of activity present in a radioactive sample.

The ionizing radiation creates ions, which conduct a current that is detected by the instrument.

CROPS

SMOKE DETECTORS AND MEASUREMENT

HALF LIFE Time required for half of the sample to

decay into a new element. This can be used to date old artifacts

such as rocks and things that were once living.

A long half life means that the substance stays relatively unchanged for a long period of time.

CARBON DATING

URANIUM IS USED TO DATE ROCKS

IODINE-131 IS USED TO TREAT THYROID DISORDERS

C-14 AND P-32 ARE USED AS TRACERS

CO-60 IS USED TO TREAT CANCER

WARFARE

CHERNOBYL In April, 1986 a

power plant in the Ukraine had the worst meltdown in history. The explosion resulted in nuclear fallout and evacuation of the area, once inhabited by people, schools, farms, etc.

CHERNOBYL Vegetation in the area turned red and died.

Pine trees in the area was known as the ‘”red forest.”

Animals in the area were evacuated soon after fallout but many animals died and those that survived were unable to reproduce.

Over 600,000 people were exposed but fewer than 50 people died as a direct result of the accident.

Babies born after the accident were mutated, had cancer and often had down syndrome.

Currently no one lives in Chernobyl and plans are being made to make it a long term storage facility.

THREE MILE ISLAND, PA In 1979 this power

plant also suffered a meltdown.

No deaths or injuries were reported though there was a spike in cancer rates and infant mortality rates in the area afterward.

It is currently still operating.

Uranium 238 is an unstable isotope which decays into a stable isotope in a process requiring 14 decays over 4.5 billion years.

Your objective is to write the decay equations for all 14 steps. If you have the assignment right, you will be awarded bonus points on the quiz.

The steps are:alpha, 2 beta, 5 alpha, 2 beta, alpha, 2 beta, alpha.