Standards

Describe radioactivity and nuclear decay

power point notes movie

Radioactivity I. Background Info II. Types of radiation III. Other info

What do you already know about radioactivity?

My part in producing the atomic bomb consisted in a single act:

I signed a letter to President Roosevelt, pressing the need for experiments on a larger scale

…in order to explore the possibilities for the production of an atomic bomb.

I was fully aware of the terrible danger to mankind

in case these attempts succeeded.

But the likelihood that the Germans were working on the same problem

with a chance of succeeding, forced me to this step.

I could do nothing else…

although I have always been a convinced pacifist.

To my mind, to kill in war is not a whit better

than to commit ordinary murder.

Albert Einstein, 1952

Radioactivity I. Background information

radioactivity – process of nuclear decay

nuclear decay- the breaking apart of the nucleus, it does not split!

All elements with atomic number of 83 and higher are radioactive..

INTERACTIVE PERIODIC TABLE:

As a nucleus breaks down, energy is given off.

What is this energy called?

RADIATION

radiation - energy given off during nuclear decay

II. Types of radiation

3 types of radiation 1.Alpha particles 2. Beta particles 3. Gamma rays

Alpha particles - can go only a few cm, can be stopped by paper, skin

Alpha particles come from:

Earth’s crust mining waste

Tobacco leaves give off small amounts of alpha particles.

DANGERS:

Interferes with normal cell processes

We have to eat it, breathe it or have an open wound for it to hurt us.

The greatest danger for us comes from breathing radon.

Radon, is a heavy gas and tends to collect in low-lying areas such as basements.

FYI

Some natural springs, such as those at Hot Springs, Arkansas, contain radon,

and were once considered healthful.

BENEFITS:

can be used to treat cancer by putting tiny amounts of it into a tumor.

Beta particles - can go several feet can be stopped by foil, clothes

Beta particles come from:

Earth’s crust Some old industrial instruments

People who have been given radioactive medical treatments

Nuclear accidents

FYI

At one time, strontium-90 was the major man- made beta emitter in the environment. Fallout from atmospheric nuclear testing from the 1950's to the early 1970's spread strontium-90 worldwide. However, most of the strontium-90 from these tests has now decayed away. Testing also released large amounts of cesium- 137 into the environment. Although, cesium-137 emits beta radiation, its gamma radiation is of greater concern. Some cesium-137 from fallout remains in the environment, but most of it has decayed as well.

DANGERS:

Interferes with normal cell processes

Causes burns

Most damage is done if we eat it, breathe it or have an open wound.

BENEFITS:

Medical treatments ex)radioactive iodine

Gamma rays - Can go thousands of meters

go the speed of light

can be stopped by thick dense objects such as lead or concrete

No particles are involved, they are energy

Gamma rays come from:

Space Nuclear accidents

DANGERS:

Radiation sickness - large exposures in short time periods,

the most severe damage of all radiation: burns, blindness, cancer,death

BENEFITS:

treat cancer sterilize medical equipment in hospitals clean certain foods and spices

astr.gsu.edu/HBASE/NucEne/radexp.html

In the United States, a person’s average exposure to radiation is about 360 millirem per year. Roughly 300 millirem come from natural sources of radiation, and 60 millirem come from man-made sources, primarily medical procedures.

More info on exposure:

half – life = time it takes for half of the nucleus to break apart

Sodium hrs Iron 59 – 45 days Cobalt 60 – 5 yrs

Uranium mill yrs.

III. Other Info

Carbon -14 dating

33,000 YR OLD DOG SKULL

Baby wooly mammoth

Conclusions The results of radiocarbon measurements at Arizona, Oxford and Zurich yield a calibrated calendar age range with at least 95% confidence for the linen of the Shroud of Turin of AD (rounded down/up to nearest 10 yr). These results therefore provide conclusive evidence that the linen of the Shroud of Turin is mediaeval.

or-fake

GALILEO’S FINGER

Carbon on the periodic table is Carbon – 12. It is stable – it does not decay.

Carbon – 14 is an isotope of Carbon – 12.

Carbon – 14 is not stable. It will decay.

It takes 5,700 years for half of the nuclei in Carbon – 14 to break down.

Carbon – 14 has a half life of 5,700 years.

Plants use CO 2 for photosynthesis so they have Carbon – 14 in them.

Animals eat plants so animals have Carbon – 14 in them.

Living things also have Carbon -12 in them.

The amount of Carbon-14 and Carbon – 12 in a living thing remains constant.

All living things have the same percentage of Carbon-14 and Carbon -12.

When a living thing dies, the amount of Carbon -12 stays the same because…

Carbon -12 does not decay (it is not radioactive).

Carbon – 14 does break down.

We can measure the amount of Carbon -1 2 and Carbon -1 4 in the fossil.

Scientists burn a small piece of the object.

A radiation counter measures the amount of Carbon -14 and Carbon - 12.

By comparing the amounts, we know how much Carbon - 14 should be there.

A formula is used to figure out the age.

Carbon dating is only good for fossils up to 60,000 years old. Why?

5,700 ½ 5,700 5,700 ½ ½ ½ ½ and on and on …

SO what do I REALLY need to know? AHHHHHHHHHHHHHHHHH!

Carbon – 14 Dating Carbon -1 4 is radioactive

small piece of the artifact must be burned to test it

half life is 5,700 years

used to age artifacts up to 60,000 years old

Why is Carbon- 14 only good for dating artifacts up to 60,000 years old?

Since the half-life of Carbon-14 is 5,700 years, all of it will have decayed into Carbon-12 in 60,000 years.

nuclear decay – nucleus doesn’t split, it just breaks down

Benefits of nuclear energy

Reduces dependence on oil for electricity

No pollutants released into atmosphere

(burning of coal pollutes atmosphere)

Drawbacks of nuclear energy

storage of waste – it can last thousands of years

(Waste from burning coal can last forever)

waste/F38D3BEBA9CDE7639FD2F38D3BEBA9CDE7639FD2 YUCCA MT. Katie Courick Shutting it down

meltdown – chain reaction cannot be stopped,

the core overheats releasing radiation

In the night of April 26, 1986

the explosion of the nuclear reactor in Chernobyl,

the greatest industrial disaster in the history of humankind,

released one hundred times more radiation

than the atom bombs dropped over Hiroshima and Nagasaki.

More than 40 different radionuclides escaped,

notably in the first ten days following the accident.

Radioactive iodine, with a half –life of 8 days, posed the greatest risk in the first few weeks.

Radioactive caesium, with a half life of 30 years, is still the most widely dispersed isotope. Between and km2 are contaminated with caesium.

There is long term contamination with strontium which has a half life of 29 years,

and plutonium with a half -life of

24,000 years.

Chernobyl disaster incident PART 1 Vacation in chernobyl (no pw) Chernobyl mystery It happened in…