Nuclear reactions - Chemical Ideas 2.2
Radioactive Isotopes
In some isotopes their nuclei is unstable. When an isotope has an unstable nuclei it can result in being radioactive. There are three different types of radioactive nuclei and they are all able to knock electrons of atoms and forming ions. They are sometimes referred to as Ionising radiation.
In some isotopes their nuclei is unstable. When an isotope has an unstable nuclei it can result in being radioactive. There are three different types of radioactive nuclei and they are all able to knock electrons of atoms and forming ions. They are sometimes referred to as Ionising radiation.
α particle and radioactive decay
When an element collides with α particles neutrons are released and a new element will be formed.
β particle and radioactive decay
γ radiation and radioactive decay
γ radiation – in gamma radiation there is no charge however energy is energy is released from the nuclease. Gamma radiation is normally found with alpha and beta particles.
Exam tipBoth sides of an equation should have the same Mass and Atomic number as each other in order to make them balanced if this is not the case then you need to go back over your work and do it again
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Exam tipDuring Alpha and beta emissions, the atomic number of an element can change as a result of this the element changes as well you should look up the symbol or atomic number in order to find the name of the element.
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Half-life
The half-life of an element is the time it takes for half the radioactive nuclei in a sample of that element to decay. The half-life of an element is not affected by temperature.
Half-life can be used to date backs archaeological artefacts if the artefact is made from something that was living (wood, bone) however some igneous rocks can also be dated because they contain radioactive isotopes.
Example 1
Iodine- 131 has a half-life of 8 days. If you start with 68 grams of the isotopes, what mass remains after 32 days?
Step 1 after 8 days, 34 grams remain
Step 2 after 16 days, 17 grams remain
Step 3 after 24 days, 8.5 grams remain
Step 4 after 32 days, 4.25 grams remain
Example 2
Element x has a half-life of 2634 years. How long will it take for the sample`s count rate to decrease from 200 countsmin-1 to 25 countsmin-1.
Step 1 after one half-life, he count rate would be 100 countsmin-1.
Step 2 after two half-lifes, the count rate would be 50 countsmin-1.
Step 3 after three half-lifes, the count rate would be 25 countsmin-1.
Step 4 time taken is three half-lifes, 3 x 2634 = 7902
Tracers
Radioisotopes can cause damage cells and cause cancer however radioactive tracers can be injected into the body to try to locate cancer. Different isotopes can be used to detect different problems in the body.
· Most tracers have a short life span (to prevent harming the patient but to be there long enough to detect the problem)
· Most tracers that are use are gamma emitters
Nuclear fusion
In nuclear fusion two or more nuclei join in order to form a heavier element. In nuclear fusion there must be certain concisions in order for nuclear fusion to take place.
· A high temperature
· Sometimes a high pressure
When two atoms join together using nuclear fusion they use the high temperature and pressure to overcome the repulsion between the two positive nuclei, because high temperatures and pressures are needed for nuclear fusion it often occurs in star formation.
Half-life can be used to date backs archaeological artefacts if the artefact is made from something that was living (wood, bone) however some igneous rocks can also be dated because they contain radioactive isotopes.
Example 1
Iodine- 131 has a half-life of 8 days. If you start with 68 grams of the isotopes, what mass remains after 32 days?
Step 1 after 8 days, 34 grams remain
Step 2 after 16 days, 17 grams remain
Step 3 after 24 days, 8.5 grams remain
Step 4 after 32 days, 4.25 grams remain
Example 2
Element x has a half-life of 2634 years. How long will it take for the sample`s count rate to decrease from 200 countsmin-1 to 25 countsmin-1.
Step 1 after one half-life, he count rate would be 100 countsmin-1.
Step 2 after two half-lifes, the count rate would be 50 countsmin-1.
Step 3 after three half-lifes, the count rate would be 25 countsmin-1.
Step 4 time taken is three half-lifes, 3 x 2634 = 7902
Tracers
Radioisotopes can cause damage cells and cause cancer however radioactive tracers can be injected into the body to try to locate cancer. Different isotopes can be used to detect different problems in the body.
· Most tracers have a short life span (to prevent harming the patient but to be there long enough to detect the problem)
· Most tracers that are use are gamma emitters
Nuclear fusion
In nuclear fusion two or more nuclei join in order to form a heavier element. In nuclear fusion there must be certain concisions in order for nuclear fusion to take place.
· A high temperature
· Sometimes a high pressure
When two atoms join together using nuclear fusion they use the high temperature and pressure to overcome the repulsion between the two positive nuclei, because high temperatures and pressures are needed for nuclear fusion it often occurs in star formation.