Nuclear Chemistry

By: Madelyn, Jack, Ali, Evan and Sierra

Lesson 10.1All about Radioactivity

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● Was experimenting Uranium salts which glowed after being exposed to sunlight

● He wanted to repeat this experiment, but bad weather forced him to wait

● Took the Uranium salts and wrapped them in photographic paper

● After a couple of days he got a foggy image even without being exposed to sunlight

Antonio Becquerel

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● Atoms of one element change into atoms of a different element altogether

● Scientists can detect a radioactive substance by measuring the nuclear radiation it gives off

● Nuclear radiation is charged particles and energy that are emitted from the nuclei of radioisotopes

● Common types of nuclear radiation is alpha, beta, and gamma

● There is also background radiation(radiation that cosmic from plants, animals, rocks, the air, and cosmic rays)

Nuclear Decay

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● Positively charged particle made of two protons and two neutrons and has +2 charge

● Common symbol is ⁴2He● Least penetrating type of radiation● Can be stopped by sheet of paper or clothing

Alpha Decay

Radiation Type Symbol Charge Mass (amu) Common Source

Alpha particle ⍺, ⁴2He +2 4 Radium-226

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● Electron emitted by unstable nucleus ● Has charge of -1● Common symbol is ⁰-1e● Can be stopped by a thin sheet of metal

Beta Decay

Radiation Type Symbol Charge Mass (amu) Common Source

Beta particle β, ⁰-1e -1 1/1836 Carbon-14

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● Penetrating ray of energy emitted by an unstable nucleus

● Common symbol is 𝛾● Strongest type of radiation● Stopped by thick slice of lead or concrete● No charge or mass

Gamma Decay

Radiation Type Symbol Charge Mass (amu) Common Source

Gamma ray 𝛾 0 0 Cobalt-60

Lesson 10.2Half-Lifes

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● Half-Life is the time it takes for one type of atom to change into another atom

● Every atom has a different length of a half-life depending on atom

● This is the way that scientists have figured out how long dinosaurs have lived

Background Info

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Radon-222 has a half-life of 3.82 days

If its been 3.82 days there will be half of radon left and a half of another element

Be careful-it might not be cut in half so perfectly. This is just a educated guess. Radon atoms half a 50% chance of changing after 3.82 days.

Example

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In this lab you are going to test the amount of halfs life in M&Ms. This is going to simulate half-lives in

real elements.

Lab

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Materials:M&Ms, graph paper, pencil

Lesson 10.3Artificial Transmutation

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What is it? Artificial transmutation is the conversion of one element to another element artificially.

Can be achieved by nuclear reactions or radioactive decay

Artificial transmutation is a nuclear change, not a chemical change

Artificial transmutation happens when scientists bombard nucleus of an atom with protons, neutrons or alpha particles (this happens with a particle accelerator).

Early alchemists tried to turn lead into gold, but they were unsuccessful.

Artificial Transmutation

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Artificial vs. Natural Transmutation

Natural Transmutation● Always has one nuclear

reactants● Spontaneous process

○ Occurs naturally without assistance

Artificial Transmutation● Always has two or more

nuclear reactants● Controlled Process

○ Forced and will not occur naturally

○ Fission and fusion are artificial transmutation

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Particle Accelerators● Ernest O. Lawrence built the first functioning

particle accelerator● It was created in the University of California● There are two types: linear and circular● Accelerator mass spectrometry (AMS) uses a large

nuclear particle accelerator and is replacing conventional Carbon-14 dating techniques

● Patients are receiving accelerator-based diagnoses and therapy for cancer

● They are 100,000 times stronger than the gravitational pull of the earth

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Particle Accelerators● If a particle were to travel in a circular particle

accelerator for 10 hours it would travel 6 billion miles, that is the distance to the furthest quarters of our solar system and back to earth again

● The inside of a particle accelerator can get hotter than the center of our sun

● In another part of the accelerator it can get as cold as -456 fahrenheit, that's colder than outer space

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Particle Accelerators● They are used for artificial transmutation● They bombard particles● Particle accelerators work by pushing

a positively charged particle and putting it through negatively charged rings to make it move faster and collidewith another particle

● They have 9,600 “super” magnets inside them● There are over 30,000 in the world right now● It has a circumference close to 17 miles● It moves particles close to the speed of light● Was used to create over 3000 isotopes● It is used for experiments

○ Study nuclear structure

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LabForm into small groups, no more than fourSend one person from your group to grab 3 ot 4 washers, grab different sizes to experiment with

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What Happens When You Put Your Head Inside a Particle

Accelerator?On July 13 in Russia Anatoli Bugorski went into the

particle accelerator to see why a piece wasn’t working, but the safety mechanism failed and the particle hit him in the head. He said didn’t feel any pain, but that he saw a light brighter than a thousand suns. The proton entered the back of his head and went out through the bottom of his nose. The particle burned through his bones and through his brain tissue. After the incident his skin started peeling, he lost hearing in his left ear, and had constant tinnitus. He is now 76 and the left side of his face is becoming paralyzed, so he doesn't have wrinkles on the side of his face. He also suffers from random seizures.

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● Transuranium elements are elements with atomic number greater than 92

● All are reactive and are not found in nature● They were made with a particle accelerator● Transmutation on a lighter element (an element with

an atomic number less than 92) produces a transuranium element

● Not often useful for everyday life● Americium-241 is used in smoke detectors

○ The Americium-241 breaks down and creates and electrical current in the smoke detector. When smoke enters the smoke detector it stops the current and the alarm goes off

Transuranium Elements

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In 1919, Ernest Rutherford performed the first artificial transmutation by exposing nitrogen gas to alpha particles. It produced oxygen and hydrogen protons, and it led to the discovery of protons in the nucleus.

Ernest Rutherford

Lesson 10.4All About Nuclear Forces, Fission, And

Fusion

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A nuclear force is what hold the nucleus (protons and neutrons) together.

Over very short distances, the nuclear force is greater than the electric forces among protons.

The larger number of electric forces makes the nucleus less stable.

Nuclear Forces

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Background: In 1938, Otto Hahn and Fritz Strassman tried to produce more massive elements by bombarding uranium-235 with high-energy neutrons. Instead of producing a bigger element, the nuclei had been broken into smaller fragments. These two German chemists had demonstrated the first nuclear fission

Fission is the splitting on an atomic nucleus into smaller parts.

Fission

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In nuclear fission, tremendous amounts of energy can be produced from very small amounts of mass.

Albert Einstein discovered the equation E=mc2

E=Energym=Massc=Speed of light

This equation describes how mass and energy are related.

Fission

In a chain reaction, neutrons released during the splitting of an initial nucleus trigger a series of nuclear fission.

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Let’s play a quick game!

Telephone

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There are two types of nuclear fission: controlled and uncontrolled chain reactions

Nuclear weapons use uncontrolled chain reactions.

Heat from controlled chain reactions can be used to generate electrical energy, but another product of controlled chain reactions is radioactive waste.

Critical mass is the smallest possible mass of a fissionable material that can sustain a chain reaction.

Fission

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Nuclear power plants control nuclear fission to generate electrical energy.

Today, nuclear power plants produce 20% of the electricity in the United States.

Thankfully, nuclear power plants do not pollute the air.

Fission

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The three disadvantages of nuclear power plants supplying energy is that workers must wear protective clothing at all times, radioactive waste must be isolated, and the operators of the plant could lose control of the reactor.

Fission

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Nuclear Power PlantControl rods in the reactor absorb neutrons to slow and control chain reactions of fission.

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Everybody take a balloon!

Quick Simulation

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Fusion is a process in which the nuclei of two atoms combine to form a larger nucleus.

The sun uses fusion to convert hydrogen to helium.

Plasma is a state of matter in which atoms have been stripped of their electrons.

Fusion

Fusion occurs at millions of degrees Celsius.

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Vocabulary● Quark: a subatomic particle theorized to be among the basic

units of matter● Fission: the splitting of an atomic nucleus● Radioactivity: the process in which an unstable atomic

nucleus emits charged particles and energy● Radioisotope: an isotope with an unstable nucleus● Alpha Particle: A positively charged particle, emitted by

certain radioactive nuclei● Beta Particle: an electron emitted by an unstable nucleus● Background Radiation: nuclear radiation that occurs naturally

in the environment● Plasma: A state of matter in which atoms have been

stripped of their electrons.● Chain Reaction:Process in which the product themselves

promote or spread the reaction in a chemical reaction.

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Vocabulary● Half-life: the time required for one half of a sample of a

radioactive isotope to decay● Strong nuclear force:the powerful attractive force that binds

protons and neutrons together in Transuranium Elements the nucleus● Atom Bomb:weapon with great explosive power that results from the

sudden release of energy upon the splitting, or fission, of the nuclei of a heavy element such as plutonium or uranium.

● Fusion: a nuclear reaction in which the nuclei of two atoms combine to form a larger nucleus

● Critical Mass: the smallest possible mass of a fissionable material that can sustain a chain reaction

● Gamma Particle: a penetrating form of radiation emitted by an unstable nucleus

● Transuranium Elements: Elements with atomic numbers greater than 92

Thanks For ListeningAny questions?

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