ISOTOPES. Isotopes Atoms with the same number of protons, but different numbers of neutrons. Atoms of the same element (same atomic number) with different.

ISOTOPES

Isotopes

Atoms with the same number of protons,

but different numbers of neutrons.

Atoms of the same element (same atomic

number) with different mass numbers

Isotopes of chlorine

35Cl 37Cl17 17

chlorine - 35 chlorine - 37

Notation for Atoms

12C13C C

only one isotope of carbon

all isotopes of carbon

only one isotope of carbon

• Since both isotopes have the same number of protons and electrons, they have identical chemical properties.

• Since physical properties depend on the mass of particles as well, isotopes will often have slightly different physical properties such as density, rate of diffusion etc.

Isotopes of Hydrogen element

H

H

H

11

21

31

has the biggest abundance in nature.

Different isotopes of Hydrogen

• Ice floats on water, but what about "heavy ice"?

Heavy water, D2O instead of H2O, is water in which both hydrogen atoms have been replaced with Deuterium, the isotope of hydrogen containing one proton and one neutron.

Basic Definitions• “atomic number” = number of protons in the

nucleus;

• “mass number” = sum of protons + neutrons in the nucleus

• “isotopic mass” = mass of a single isotope

Radioactive isotopes

are produced by exposing the natural element to a flux(flow) of neutrons in a nuclear reactor. The nucleus of an atom captures an additional neutron and form “radioisotope”.

Radioisotopes

• Is a short term for “radioactive isotope.”

• Radioisotopes have unstable nuclei. That means, sooner or later, the nucleus breaks down naturally or decays, giving out radiation in the form of rays and particles.

Radioactive vs. Non-radioactive isotopes

12C13C14C

Non-radioactive

Radioactive

Non-radioactive

Examples of Radioisotopes

• 14C or Carbon-14

• Cobalt-60

• Iodine-127

• Cesium-137

Making Use of Radioisotopes in Industry

1) To check for Leaks:- Oil and gas pipelines for leaks are checked by

adding radioisotopes to the oil or gas. - Geiger counter is used for this.- The counter does not detect the radiation when

the radioisotopes are in the pipe

but can detect them outside the pipes or where the leaks are.-Such radioisotopes are called as “tracers.”

Making Use of Radioisotopes in Industry

1) Source of energy:

Uranium-235 is mostly used for this.

Making Use of Radioisotopes in Industry

1) Source of energy:-8 kWh of electricity can be generated from 1 kg of coal, approx. 12 kWh from 1 kg of mineral oil and around 24,000,000 kWh from 1 kg of uranium-235. Related to one kilogram, uranium-235 contains two to three million times the energy equivalent of oil or coal.

Making Use of Radioisotopes in Industry

1) Source of energy:-Over 13% of the world's electricity is generated from uranium in nuclear reactors.-Nuclear energy has a long term nature (sustainable long after coal and oil run out in the world).-Radioactive waste is hazardous to most forms of life and the environment, and is regulated by government agencies in order to protect human health and the environment.-Radioactive waste is managed by deep burial.

Making Use of Radioisotopes in Medicine

1) To treat cancer:

- They are used in radiotherapy to cure cancer.

Gamma rays in radiation kill cancer cells more readily than normal cells.

Making Use of Radioisotopes in Medicine

2) To kill germs and bacteria:

- Gamma rays kill germs too.

Gamma rays are used to sterilize food.

Gamma rays are used to sterilize syringes and other medical equipment.

Cobalt-60 and Cesium-137 isotopes are used for these purposes!!!

Making Use of Radioisotopes in Medicine

3) as tracers.- Iodine-131 or Iodine-125, both are beta emitters, is taken as sodium iodide in

drinking water. Almost all of it will find its way to the thyroid. The rate of iodine-131 absorbance by the thyroid gland, determined with a Geiger counter or other scanning device, indicates whether the thyroid glands are functioning properly.

Making Use of Radioisotopes

Carbon Dating:

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