Modern Atomic Theory

• All matter is made of tiny particles called ______ Each atom is made up of smaller subatomic particles called ___________________________________________

• The atoms of one element cannot be converted into the atoms of any other element by ____________________

• All the atoms of one element have the ______________, such as average _______________. These properties are different from properties of the atoms of any other element. (what law explains this?)

• Atoms of different elements combine in _____________________________ (what law explains this?)

Lesson #4 - Radioisotopes

Review of Isotopes

• Same number of ___ but have a different number of ____

• Same _________________ but a different _______________________

• Many elements (~69) that exist as __________

Isotopic ElementsElement Atomic

No.Mass No.

Symbol No. of Protons No. of Neutrons Abudance

HydrogenDeuterium

Tritium

111

1.00782.01413.0161

1H1

1D2

1T3

111

012

99.99%0.02%rare

Oxygen 888

161718

8O16

8O17

8O18

888

89

10

99.76%0.04%0.20%

Chlorine 1717

34.9736.97

17C135

17C1371717

1820

76%26%

Neon 1616

2022

16Ne20

16Ne221616

46

90%10%

3 Types of Change

• 1. Physical • 2. Chemical• 3. Nuclear

Reaction: change that occurs within ________________________________

Nuclear Reactions

• The number of ________ in the nucleus change

• This reaction can convert an atom of one element ___________________________

• Nuclear reactions involve _____________________________________

• Eg. The sun, nuclear power station, nuclear reactor, nuclear bomb.

Old School Atom DocumentaryNuclear Reactions

• http://www.youtube.com/watch?v=_f4kYYAQC3c&feature=related

• http://www.youtube.com/watch?v=RMWOfbcAbgo&feature=related

RadioactivityRadioactivity is the term used to describe the natural process

by which some atoms of _______________ of elements spontaneously disintegrate, emitting particles and energy as they transform into more ____________________.

Atoms of some elements are unstable, having ______________________________________________ An unstable nucleus emits particles and energy until it becomes stable.

Some chemical elements, including uranium, radium, thorium, and polonium, are ___________________. Any element that is not naturally radioactive can be made radioactive in a nuclear reactor or particle accelerator.

Radioactivity

Each radioactive element, _________________, has a ____________________, which is the time it takes for one half of the atoms of a particular radioisotope to disintegrate (or decay) into another nuclear form.

The longer the half-life of a radioisotope, _____________________________________________

Uranium -238

• Uranium can be found in low levels in all rock, soil and water. It occurs in most rocks in concentrations of 2 to 4 parts per million and is also found in the oceans, at an average concentration of 1.3 parts per billion.

• http://www.bbc.co.uk/news/world-europe-11074645

Isotopes of Uranium 238

• Uranium is a _______________, comparable to lead.

• Uranium is as common as tin, tungsten and molybdenum, and about 40 times as common as silver.

• Most uranium exists as ______________________ (99.2745 %). The rest is __________________________________

Uranium and Nuclear Reactors

• The rare uranium isotope U-235 is the fuel most widely used by nuclear plants for fission because its ____________________________________

• One ton of uranium can produce more than 40 million kilowatt hours of electricity, equal to 16,000 tons of coal or 80,000 barrels of oil.

• There are a number of areas around the world where the concentration of uranium in the ground is sufficiently high that it can be economically extracted for nuclear fuel. ____________________________________________

Uranium 235

General

Name, symbol Uranium-235,235U

Neutrons 143Protons 92

Uranium 238Nuclear Equation

• Rules for balancing nuclear reactions:• 1. The ____ of the ____________ (top) on

each side of the ______________________• 2. The ____ of the _______________ (bottom)

on each side of the equation must ___________

• Side note: you have been assigned only equations dealing with alpha particle emission, or alpha decay. You will learn about the effects of beta and gamma rays, but in terms of equations, you only need to know those elements that lose a helium nucleus. (2 protons and 2 neutrons) Helium will always be a part of your products, on the right side of your nuclear equation. This is discussed in more detail on pg. 142-143 (top only) of your textbook.

Uranium 238Nuclear Equation

• After time, radioactive elements begin to _______• Uranium decays into atoms of

_____________________________

• Note that ______________________ have formed the nuclei of the ___________________and that it’s neutrons have also become part of the new nuclei

• This is an example of ______________, where an alpha particle is a helium nucleus, composed of 2 p+ and 2n0

Practice Problems

• Radon-222 is known to decay by alpha particle emission. Write a balanced nuclear equation and name the element produced in this decay process.

• Write the balanced nuclear equation for Plutonium-242

• Write the balanced nuclear equation for Neodymium-144.

Radioactivity

• When new nuclei are formed, _______________________________ speed away from the reaction into the surrounding environment.

• This stabilizing process emits _______________________________________from the nucleus, each of which is energetic enough to break chemical bonds and able to damage or destroy living cells.

• This radioactivity is also known as ___________________________

Ionizing Radiation

• http://www.youtube.com/watch?v=K_zc1WKT0CA• Ionizing Radiation removes _____________ from

molecules in living tissues and can seriously disturb their function. Nuclear radiation is a form of ionizing radiation.

• Another form frequently used in medicine are x-rays. X-rays do not come from the nuclei of unstable atoms, but are produced by machines that which accelerate electrons to produce a beam of high energy waves.

What radiation comes out of X-Rays

• http://www.ehow.com/video_5112777_radiation-comes-out-x_rays_.html

• Radiation from X-rays is similar ______________________________, so the same precautions must be taken.

Penetrating PowerDepending on the type of nuclear reaction, different types of radioactivity are

emitted as the nucleus decays.

Background Radiation

• http://www.youtube.com/watch?v=IXpm5ihBSPM&feature=related

• Radon-222• Cosmic radiation• Potassium-40 in the body• Polonium-210 in tobacco (smokers are

exposed to more than 3x the radioactivity than non-smokers)

Naturally Occurring Radioisotopes

• There are about 30 naturally occurring radioisotopes which are __________________________________, transforming over time into other elements.

• Eg. Carbon-14, Chlorine-36, Lead-210• These isotopes are used in radiometric dating,

mostly known as ___________________

Carbon Dating?

Carbon-14 Dating

• http://science.howstuffworks.com/environmental/earth/geology/carbon-14.htm

• The ________ of carbon-12 to carbon-14 at the moment of death is the same as every other living thing, but the carbon-14 ________________________

• The carbon-14 decays with its half-life of ___________, while the amount of carbon-12 remains constant in the sample.

• By looking at the ratio of carbon-12 to carbon-14 in the sample and comparing it to the _______________________it is possible to determine the age of a formerly living thing fairly precisely.

Artificially Produced Radioisotopes• Americium-241:

Used in backscatter gauges, smoke detectors, fill height detectors and in measuring ash content of coal.

• Caesium-137:Used for radiotracer technique for identification of sources of soil erosion and deposition, in density and fill height level switches.

• Chromium 57:Used to label sand to study coastal erosion.

• Cobalt-60, Lanthanum-140, Scandium-46, Silver-110m, Gold-198:Used together in blast furnaces to determine resident times and to quantify yields to measure the furnace performance.

• Cobalt-60: Used for gamma sterilization, industrial radiography, density and fill height switches.

AECL Chalk River – Medical Isotopes

• http://www.youtube.com/watch?v=aUJueJEZKoo&feature=related

Factors to take into consideration when using medical radioisotopes

Penetrating Power

“The Radium Girls”• The Radium Girls were a

group of female factory workers who contracted radiation poisoning from painting watch dials with glow-in-the-dark paint at the United States Radium factory in Orange, New Jersey around 1917. The women, who had been told the paint was harmless, ingested deadly amounts of radium by licking their paintbrushes to sharpen them; some also painted their fingernails with the glowing substance.

Rate of Radioactive Decay

• __________________• Some radioisotopes take hours to decay and

some take years.• Determines shelf life, transportation, disposal,

and how long the _____________________________________________

• Eg. Molybdenum-99 from AECL = 66h, Technetium-99 = 6h.

Size of Dose

• A large dose of radioactivity in a few hours is way _______________ then that same dosage _______________________________

• People who work with radiation wear special counters to ensure their accumulated exposure is well below the accepted time.

• Radiation is measured in RADS – ____________________________

• Matt will talk more about this

Type of Tissue

• Exposure to body cells can cause _________________

• Exposure to __________ can affect human offspring – called _________________

• Biology review!

Reproduction is amazing!Chemistry + Biology +(unfortunately) Physics = circle of __________________

Uses of Medical Isotopes

• A radioisotope used to diagnose abnormalities such as ________________________ must have a good penetration and be easily detected. What kind of radioisotopes do you think would be best to use?

• The radioisotope must be an element needed by the tissue and also _________ in such a way that there is time for the body to take it into the tissue and for a scanner to detect it.

• It’s ____________________________________ that it will not stay in the body long enough to cause damage.

Technetium-99

• One of the first ____________________

• Discovery: Carlo Perrier, Emilio Segre 1937 (Italy) found it in a sample of molybdenum that had been bombarded with neutrons.

• Technetium-99 is used in many medical ____________________

Technetium scintigraphy of a neck of Graves' disease patient

In the use of technetium-99m, the radioisotope is administered to the patient and the escaping ____________________ are incident upon a moving gamma camera which computes and processes the image.

Technetium-99m ____________________________and emits primarily a gamma ray (allowing small amounts to be easily detected), its quick decay into the far-less radioactive technetium-99 results in relatively _________________________________per unit of initial activity after administration, as compared to other radioisotopes.

Uses of Medical Radioisotopes

• http://www.youtube.com/watch?v=OK7yOyI6GLI&feature=related

• Radioisotopes are used both _____________________________ to treat cancer because they destroy rapidly dividing cells.

• High energy gamma radiation can come from ___________________________

Internal Radiation Therapy

• Radioisotope must be ____________ into the tumor

• __________________ radioactivity usually used.• Radiation accumulates in the tumor and destroys

the tumor and not the surrounding tissue.• ______________________________________ are

surgically implanted into tumors• ____________________ is used to battle leukemia• _________________ is used for thyroid problems

Sterilization of Medical EquipmentCobalt-60

• As a tracer for cobalt in chemical reactions,

• _______________________________________________

• Radiation source for medical radiotherapy,

• Radiation source for industrial radiography,

• Radioactive source for leveling devices and thickness gauges,

• As a radioactive source for food irradiation and blood irradiation, and

• ______________________________________________

Lots of new stuff…………..

• Any questions?• Take some time now and try the questions in

the Self-Check #1 section• Make note of any specific questions to ask our

guest speaker, Matt.• Homework: all the questions for lesson #4.

There are quite a few so it makes me think that this stuff is important!

• Readings for Lessons #5 & #7 (6 is the lab)