Radioactivity figure

What we are going to explain

what is radioactivity? Discovery of radioactivity. Radiation and where does radiation comes from? Three types of radiation. Uses field of radiation. Effects of radiation. Radiation controls. Half life of radiation. Advantages and disadvantages.

Discovery of Radioactivity• In 1896 Henri Becquerel put a

sample of uranium on a photographic plate. The Uranium left an outline. He hypothesized that the uranium was emitting invisIIible rays.

• 2 years later, Marie and Pierre Curie isolated radium from pitchblend.

RadiationRadiation: The process of emitting energy in the form of waves or particles.

Where does radiation come from?Radiation is generally produced when particles interact or decay.

A large contribution of the radiationon earth is from the sun (solar) or from radioactive isotopes of the elements (terrestrial).

Radiation is going through you atthis very moment

Three types of radiation were known

1)Alpha particles ()

2)Beta particles ()

3)Gamma-rays ()

Alpha particle

Alpha particle - these are fast moving helium atoms. They have high energy, typically in the MeV range, but due to their large mass, they are stopped by just a few inches of air, or a piece of paper.

• 23892U → 4

2He + 23490Th

• The helium nucleus is the alpha particle.

Beta particle• Beta particle - these are fast moving

electrons. They typically have energies in the range of a few hundred keV to several MeV. Since electrons are might lighter than helium atoms, they are able to penetrate further, through several feet of air, or several millimeters of plastic or less of very light metals.

•

• 23490 → 0

-1e + 23491Pa

• • The electron is the beta particle.

Gamma particle

Gamma particle - These are photons, just like light, except of much higher energy, typically from several keV to several MeV. X-Rays and gamma rays are really the same thing, the difference is how they were produced. Depending on their energy, they can be stopped by a thin piece of aluminum foil, or they can penetrate several inches of lead.

Uses field of radiationa. Cancer Treatmentb. Killing Microbesc. Carbon Datingd. Dating rocks

Cancer treatment

• Gamma rays are capable of passing deep inside the body and damage cells on their travels. But as well as causing cancer, they can be used to kill off cancer cells and even cure people from this illness. This treatment is called radiotherapy

Killing microbes

• Gamma rays successfully kill microbes that cause food to decay. So food treated with this radiation have a longer shelf life. Surgical instruments and syringes are also treated with gamma rays, in order, to prevent infections been transferred from patient to patient.

Carbon Dating

• When an animal or plant dies it stops taking in carbon. But its carbon-14 content continues to decay. If we compare the carbon-14 with that from a living thing, and knowing the half-life of carbon-14, the age of animal and plant remains can be calculated. This is known as carbon dating.

Dating rocks

•Twelve out of every 1000 potassium atoms is the radioistope potassium-40. Its half life is a staggering twelve thousand years and decays to eventually form the stable argon atom. By measuring the argon content of many rocks that contain potassium, scientists can calculate the age of the rock.

RADIATION CONTROLS• Time: Minimize time of exposure to minimize total dose. Rotate

employees to restrict individual dose.

• Distance: Maximize distance to source to maximize attenuation in air. The effect of distance can be estimated from equations.

• Shielding: Minimize exposure by placing absorbing shield between worker and source.

Half-Life

• Amount of time it takes for one half of a sample of radioactive atoms to decay

Medical Applications of Half-Life

Nuclide Half-Life Area of Body

I–131 8.1 days Thyroid

Fe–59 45.1 days Red Blood Cells

Sr–87 2.8 hours Bones

Tc–99 6.0 hours Heart

Na–24 14.8 hours Circulatory System

Half-Life Calculation #1• You have 400 mg of a radioisotope with a half-life of 5 minutes.

How much will be left after 30 minutes?

Answer: 6.25 mg

Half-Life Calculation #2

• Suppose you have a 100 mg sample of Au-191, which has a half-life of 3.4 hours. How much will remain after 10.2 hours?

Answer: 12.5 mg

Examples of Half-LifeIsotope Half lifeC-15 2.4 secRa-224 3.6 daysRa-223 12 daysI-125 60 daysC-14 5700 yearsU-235 710 000 000 years

ADVANTAGES

1. Radiation needs no medium in order to be able to take place.

2. It travels very fast.

3. Doctors sometimes insert a little amount of radioactive element inside us in order to be able to see cancerous cells or broken bones.

4. Radioactive elements contain a huge amount of energy stored inside them.

DISADVANTAGES

• 1. Radiation is dangerous (Ultra violet light is divided into U.V.A and U.V.B, and U.V.B is dangerous and causes cancer. radiation from radioactive elements are lethal to human beings)

2. Radiation waves are present everywhere in our everyday live( radio waves, WI-FI, Bluetooth) Ant these cause infertility and develop cancerous cells, with time.