Radioactivity occurs when an element has an unstable nucleus that decays by emitting radiation such as alpha, beta, or gamma rays. Radioactive isotopes are used widely in medicine for diagnosis and treatment through applications like medical imaging and radiation therapy. Some common medical isotopes used are iodine-131 for thyroid imaging and treatment, and cobalt-60 and iridium-192 which are supplied in wire form for internal radiotherapy of cancers. Radioactivity was discovered accidentally by Henri Becquerel and further research was conducted by scientists like Marie and Pierre Curie to isolate other radioactive elements.

1. Radioactivity

2.  A radioactive element is an element with an unstable nucleus,
which radiates alpha, beta or gamma radiation and gets
converted to a stable element.
 Both radioisotopes and enriched stable isotopes are essential to a
wide variety of applications in medicine, where they are used in
the diagnosis and treatment of illnesses. In addition, extensive
applications of isotopes in biomedical research finds wide parallel
uses in research chemistry, physics, biology.

3.  Radioactivity was accidentally discovered by
HENRI BECQUEREL.
 Scientists like Madam Curie and her husband
Pierre also worked hard to isolate other
radioactive elements such as Polonium and
Radium. Knowledge of radioactivity helped
scientists to work out the structures of atoms.

4. Radioactive isotopes:
 Isotope: Isotopes have the same number of
protons, but they differ in the number of neutrons.
 radioactive isotopes of an element can be defined as
atoms that contain an unstable nucleus and dissipate
excess energy by spontaneously emitting radiation in
the form of alpha, beta and gamma rays.

5. 1. Emits radiation
2. Half life(t ½)
3. Penetration property
4. Same chemical properties
5. Different physical properties

6.  Radioactive isotopes are unstable so they undergo
radioactive decay emitting radiations.
• Till they become stable.
 •
 • Alpha particles(α)
 • Beta particles(β)
 • Gamma rays(g)

7.  Alpha particles are a highly ionising form of particle
radiation.
 As its ionising power is so high it does not penetrate very
deeply into matter.
 Thus it has very low penetrating power.
 Alpha particles are the largest products of radioactivity. Hence, they
don't penetrate through many barriers like other types of radiation
do, making them the least harmful to humans.
 However, that doesn't mean humans can't find uses for them. One
common use for alpha decay is in smoke detectors,

8.  Beta particles are high-energy.
 high-speed electrons emitted by certain types of radioactive
nuclei such as potassium-40.
 Form of ionising radiation also known as beta rays.
 The high energy electrons have greater range of penetration
than alpha particles, but still much less than gamma rays.
 Beta particles can be used in manufacturing products, or in human
medicine.

9.  Gamma rays are electromagnetic radiation with high
frequency.
 When atoms decay by emitting Alpha or Beta particles to
form a new atom, the nuclei of the new atom formed may
still have too much energy to be completely stable. This
excess energy is emitted as gamma rays.
 Low ionising power.
 Very high penetrating power

10. Penetration property:

11. WHAT MAKES AN ELEMENT
RADIOACTIVE???
There are three kinds of particles inside an atom: that is protons, neutrons and
electrons. The nucleus contains the above mentioned two particles i.e. protons
and neutrons. The region beyond the nucleus contains electrons that balance
out the charge of the protons. The number of protons is equal to the number of
neutrons that is why the atomic weight is twice the atomic number. Since like
charges repel each other which results a force that tries to push the electrons
and protons apart. If the ratio of protons to the neutrons is not within certain
limits then the proton can not be held firmly together which leads to the
formation of an unstable nucleus. Making the isotopes of some elements
radioactive.

12. :
 For example, carbon, the element found in all living things
has a chemical symbol C. the normal form has an atomic
weight of 12 and is written as carbon-12, but the radioactive
version has two extra neutrons, so the symbol iscarbon-14.
 As we shall see, the radioactive form behaves chemically just
like the non-radioactive form, although one shall never
change into the other. There are three kinds of radioactivity
each with different radiation type.

13. RADIOACTIVITY:
 Radioactivity is a very interesting phenomenon in nature.
Classical Electromagnetism cannot explain radioactivity. It’s a
spontaneous and random phenomenon whereby nuclei of
certain chemical elements like Uranium, radiate gamma rays,
beta particles and alpha particles.
 By the emission of these particles and radiation, the unstable
nucleus gets converted into a stable nucleus. This is called
RADIOACTIVE DECAY.

14. APPLICATIONS OF RADIOACTIVITY:
 We could not do without radioactive materials in today’s world, even if we
wanted to. We rely on these radioactive elements every day to make us
healthier, to help supply necessities like food and electricity, keep us safer, help
us to protect our environment, add fun and convenience to our lives and help
us learn more about our world.
 Radioisotopes have found a large number of applications. Some of them are as
follows:
 Medical Diagnosis
 Generate Electricity
 Synthesis of new elements
 Preservation of food
 Smoke detectors

15. ISOTOPS COMMONLY USED IN
MEDICINE:
There are about 20 radioactive isotopes used in medicine. Each isotope
has its own use in this field.
 Chromium-51: Half life period 28 days Purpose: Used to label red blood cells and quantify
gastro- intestinal protein loss.
 Cobalt-60: Half life period is 10.5 months Purpose: Formerly used for external beam
radiotherapy.
 Erbium-169 Half life period is 9.4 days Purpose: Use for relieving arthritis pain in synovial
joints.
 Iodine-125 Half life period is 60 days Purpose: Used in cancer Brach therapy (prostate and
brain), also diagnostically to evaluate the filtration rate of kidneys and to diagnose deep
vein thrombosis in the leg. It is also widely used in radioimmunology- assays to show the
presence of hormones in tiny quantities.

16.  Iodine-131 Half life period is 8 days Purpose: Widely used in treating
thyroid cancer and in imaging the thyroid; also in diagnosis of
abnormal liver function, renal (kidney) blood flow and urinary tract
obstruction. A strong gamma emitter, but used for beta therapy.
Iodine used for curing thyroid cancer
 Iridium-192 half life period is 74 days Purpose: Supplied in wire form
for use as an internal radiotherapy source for cancer treatment (used
then removed).
 Sodium-24 Half life period is 15 hours Purpose: For studies of
electrolytes within the body.

17.  Xenon-133 Half life period is 5 days Purpose: Used for pulmonary
(lung) ventilation studies.
 Phosphorus-32 Half life period is14 days Purpose: Used in the
treatment of polycythemia Vera (excess red blood cells). Beta
emitter.
 X-Rays are used to examine the internal parts of the body that is
bones to see the fractures.

18. Applications of X-Rays
Radiography is used to diagnose the ailment and diseases of the
internal and hidden parts of the body using x-rays.
: Fluoroscopy is a type of medical imaging that shows a continuous x-ray
image on a monitor.
: Digital Subtraction Angiography (DSA) is used to image
blood vessels.
high-
energy rays are used to damage cancer cells and stop them from growing and dividing. A
specialist in radiation therapy is called a radiation oncologist.
 The Radioactive isotopic materials are very essential in curing many dreadful
diseases like AIDS, cancer and Alzheimer’s disease.

19. The form of the energies that are released from these elements in radiation therapy is
often administered by machine. The machine aims those radiations at the cancer.
Radioactive substances can also be kept inside the body of a person. These types of
treatments can cause many side effects.
 hair loss
 nausea
 vomiting
 swelling
 difficulty swallowing
 urinary and bladder changes