Isotope

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Malaysia SPM Form 4 Chemistry, Chapter 1 : Structure of Atom.

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[edit] Isotope

  • Isotopes are atoms of certain elements which have the same number of protons but different number of neutrons in the nucleus of the atoms.
  • It can also can be defined as atoms of certain elements with the same proton numbers but with different nucleon numbers.
  • Three important points to define isotopes.
  1. Isotopes are different atoms of the same element.
  2. Isotopes have the same number of protons or same proton numbers.
  3. Isotopes have different numbers of neutrons or nucleon numbers.
Properties of Isotope
Number of proton equal
Number of neutron difference
Chemical properties same
Physical properties difference



Example

Element Name Symbol Proton Number Nucleon Number Number of proton Number of neutron
Hydrogen Hydrogen   1 1 1 0
Deuterium   1 12 1 1
Tritium   1 23 1 2
Oxygen Oxygen-16   8 16 8 8
Oxygen-17   8 17 8 9
Oxygen-18   8 18 8 10
Carbon Carbon-12   6 12 6 6
Carbon-13   6 13 6 7
Carbon-14   6 14 6 8
Chlorine Chlorine-35   17 35 17 18
Chlorine-37   17 37 17 20
Sodium Sodium-23   11 23 11 12
Sodium-24   11 24 11 13

[edit] Uses of isotopes in our daily lives

  • There are two types of isotopes, namely
  1. the stable isotopes (non-radioactive)
  2. the non-stable isotopes (radioactive).
  • Unstable isotopes go through radioactive decay and emit radiation and they are known as radioisotopes.
  • Radioisotopes have many applications in daily life.
  • Several uses of radioisotopes in daily life are shown in Table below.

[edit] Medical

  • Gamma rays of cobalt-60 are used to kill cancer cells without surgery in patients. This treatment is known as radiotherapy.
  • Patients with skin cancer can be treated using beta rays from the isotopes phosphorus-32 and strontium-90
  • Medical instruments such as surgical equipment, syringes and bandages can sterilize by using gamma rays.
  • Radioisotopes are also used as tracers.
A small amount of sodium-24 is injected into the patient's body.
A radioactive detector is then used to detect accumulation of sodium-24 and therefore detect tumours and blood clots before they become dangerous.
  • This tracing method is also used to investigate the thyroid glands by measuring the uptake of iodine-131.
  • Plutonium-238 in a nuclear battery is used to produce small electric shocks in the heart pacemaker.
People with irregular heartbeats need to have a heart pacemaker implanted inside their chest.
The nuclear battery of the pacemaker provides a tiny electrical shock to ensure a steady heartbeat.


[edit] Agricultural

  • Radio isotopes are used to cause mutation in insects so as to make them sterile or to cause death. These serve as pest control in agriculture.
  • The metabolism of phosphorus by plants can be studied using phosphate fertilisers that contain phosphorus-32.
A small amount of phosphorus-32 is used in fertilisers.
The radiation produced by phosphorus-32decaying is detected by a Geiger-Miller counter.
This method can trace the passage of phosphate ions in plants..
  • Carbon-14 is used to study the passage of carbon during photosynthesis in plants.


[edit] Industrial

  • Isotope sodium-24 is used to detect leakage of underground pipes.
  • Beta rays are used to control the thickness of plastic, paper and metal sheets in factory.
  • Gamma rays are used to detect whether cans or bottles are filled up to the required amount.
  • Sodium-24 is used to measure the wear out rate of engine in a vehicle.


[edit] Food Preservation

  • The gamma rays from cobalt-60 are used to kill bacteria in food to make fresh vegetables and fruits last longer without any change in quality, flavour and texture of food.
  • Gamma rays are used to inhibit budding in potatoes.


[edit] Archeology

  • Radioisotope carbon-14 is used to study and estimate the age of ancient artifacts. This method is named as the radiocarbon dating.


[edit] Production of Energy

  • Plutonium is used in nuclear reactors to produce electrical energy.

[edit] Danger of Radioactive

  • Radioactive isotopes are very dangerous if it is misused.
  • Short-term exposure to radioactive rays may
  1. kill or destroy the cells in our body and cause organ damage
  2. cause rashes and burns on the exposed skin
  • Long-term exposure to radioactive rays may
  1. ause mutation in our genes and abnormalities in newborn babies
  2. disturb the growth and division of cells and consequently cause cancer

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