Nuclear Chemistry

“Nuclear Reaction” – Anytime the nucleus of an atom changes.

Nuclear Chemistry

Types of Nuclear Reactions:

Fission

Fusion

Radioactive Decay

Radioactive Decay

Nucleus

Fission

The splitting apart of a large atom (nucleus) into two smaller atoms

Fusion

The combining of two small atoms to produce a single larger atom

So What’s the Point?

The products of a fission and a fusion reaction weigh less than the reactants.

In other words, matter disappears!

Where does the matter go?

It turns into energy!

According to the equation: E = mc2

The point is – You get a poop load of energy!

Fission

The splitting apart of a large atom (nucleus) into two smaller atoms

“Chain Reaction”

“Critical Mass”When a hunk of fissionable material can keep reacting on its own

“Critical Mass”When a hunk of fissionable material can keep reacting on its own

Most neutrons end up leaving the solid before they can hit another nucleus.

“Critical Mass”When a hunk of fissionable material can keep reacting on its own

Thick Hunk = Chain Reaction!

The Louis Slotin Accident

On May 21, 1946, Louis Slotin and seven other colleagues performed an experiment that involved the creation of one of the first steps of a fission reaction by placing two half-spheres of beryllium (a neutron reflector) around a plutonium core. The experiment used the same 6.2-kilogram (13.7 lb) plutonium core that had earlier irradiated Daghlian, later called the "Demon core" for its role in the two accidents. Slotin grasped the upper beryllium hemisphere with his left hand through a thumb hole at the top while he maintained the separation of the half-spheres using the blade of a screwdriver with his right hand, having removed the shims normally used. Using a screwdriver was not normal part of the experimental protocol. At 3:20 p.m., the screwdriver slipped and the upper beryllium hemisphere fell, causing a "prompt critical" reaction and a burst of hard radiation. At the time, the scientists in the room observed the "blue glow" of air ionization and felt a "heat wave". In addition, Slotin experienced a sour taste in his mouth and an intense burning sensation in his left hand. Slotin instinctively jerked his left hand upward, lifting the upper beryllium hemisphere and dropping it to the floor, ending the reaction. However, he had already been exposed to a lethal dose of neutron and gamma radiation. "As soon as Slotin left the building, he vomited, a common reaction from exposure to extremely intense ionizing radiation" recorded Dr Thomas D. Brock. Slotin's colleagues rushed him to the hospital, but irreversible damage had already been done. His parents were informed of their son's inevitable death and a number of volunteers donated blood for transfusions, but the efforts proved futile. Louis Slotin died nine days later on May 30, in the presence of his parents. He was buried in Winnipeg on June 2, 1946.

“Critical Mass” (Abombs)When a hunk of fissionable material can keep reacting on its own

The Hiroshima Bomb - Due to its long, thin shape, the Hiroshima bomb was called ³Little Boy². The material used was uranium 235. It is believed that the fission of slightly less than one kilogram of uranium 235 released energy equivalent to approximately 15,000 tons of TNT

The Nagasaki Bomb - Compared to the one used on Hiroshima, the Nagasaki bomb was rounder and fatter. It was called "Fat Man." The material used was plutonium 239. The fission of slightly more than one kilogram of plutonium 239 is thought to have released destructive energy equivalent to about 21,000 tons of TNT.

• Hydrogen Bomb

• 50 Million tons TNT

• Fission of Pu

• Fusion of H

Why are some atoms radioactive?

Why are some atoms radioactive?

1) They don’t have the “proper” ratio of protons to neutrons.

Why does it end here?(atomic number 83)

yellow = protons (+)orange = neutrons

A Nucleus

What do “like” charges do?

Why don’t the protons

fly apart?

There has to be a stronger force inside the nucleus holding them together!

Strong Nuclear Force

“Electrostatic Force”

Strong Nuclear Force

The strong nuclear force is the strongest of all the forces of nature.

Weak Nuclear Force

Electrostatic Force

Gravity

But…

It only works over VERY small distances!

pink = protons (+)grey = neutrons

A BIG NucleusBecomes ineffective at a

distance that is equal the diameter of a Bismuth nucleus.

Strong Nuclear Force

too far apart

pink = protons (+)grey = neutrons

A BIG NucleusBecomes ineffective at a

distance that is equal the diameter of a Bismuth nucleus.

Strong Nuclear Force

too far apartSo the electrostatic

force takes over.

“Alpha Decay”

high speed ejection

Why are some atoms radioactive?

1) They don’t have the “proper” ratio of protons to neutrons.

2) They are too big.

Alpha Decay – emits a helium nucleus loses 2 protons and 2 neutrons

Beta Decay – emits an electron neutron turns into a proton

Electron Capture – absorbs an electron proton turns into a neutron

Radioactive Decay

Nuclear Radiation

“Radiation” Nuclear vs Electromagnetic