The alpha atom was discovered and named in 1899 by an English scientist, Ernest Rutherford while working with U ( 1 ) . Rutherford and his colleagues used alpha atoms in experiments to examine the construction of atoms in thin metallic foil. From 1909 to 1911 this work achieved the first construct of the atom: a bantam i??planetary systemi?? with negative charged atoms, negatron, revolving around a positively charged karyon, through the Rutherford-Bohr planetal theoretical account of the atom ( 2 ) .
Alpha atoms, denoted by the Greek alphabet i??ai?? , is made up of two protons and two neutrons bound together into a atom ( which is indistinguishable to a He karyon ) ( 3 ) . The alpha atom is a type of ionising radiation and is one of the most widespread signifiers of radiation. An alpha atom is basically a He karyon, which consists of two neutrons and two protons, without negatrons, giving it a net positive charge ( 4 ) . It is a comparatively heavy, high-energy atom and has a speed in air of about one-twentieth the velocity of visible radiation, depending upon the single atom ‘s energy ( 5 ) .
Due to alpha atoms comparatively high mass, they are the most destructive signifier of ionising radiation, but the tradeoff is that their incursion is low. ( 6 ) . Alpha atoms have such a low incursion force that they are able to be stopped by few centimetres of air, by the tegument or even by a piece of paper, showing small danger unless swallowed ( 7 ) .
B ) Beta Particles
Henri Becquerel discovered the beta atom in the late nineteenth century ( 8 ) . In 1900, Becquerel showed that the beta atoms were indistinguishable to negatrons, which had been late discovered by Joseph John Thompson ( 9 )
The beta atom is denoted as i??i??+i?? while the ordinary beta atom is i??i??-i?? . It is a high-velocity negatron or place released from a devolving radioactive karyon. Beta atoms have medium-energy and low mass therefore they are one of the least detrimental signifiers of radiation but still a really important wellness concern ( 10 ) . Even though beta atoms have the same belongingss as negatrons, they have much higher energies than typical negatrons revolving the karyon. Beta atoms are non of course radioactive but they can do harm, break chemical bonds and create ions and harm tissue ( 11 ) .
Bata atoms have an electrical charge of i??1 and their velocity depends on how much energy they have. The beta particlei??s extra energy, in the signifier of velocity, causes injury to populating cells and when transferred, this energy can interrupt chemical bonds and signifier ions ( 12 ) .
degree Celsius ) Gamma Rays
In 1900 Paul Villard, a Gallic chemist and physicist, discovered gamma radiation while analyzing radiation emitted from Ra ( 13 ) .
A gamma beam is a i??packeti?? of electromagnetic energy called a i??photoni?? . Gamma rays ( gamma photons ) are the most energetic photons in the electromagnetic spectrum. They are emitted from the karyon of some unstable ( radioactive ) atoms. Gamma beams have about 10,000 times every bit much energy as the photons in the seeable scope of the electromagnetic spectrum Gamma beams have no mass and no electrical charge – they are pure electromagnetic energy. Gamma radiation is really high-energy ionizing radiation ( 14 ) .
The gamma beams, denoted as i?? ? i?? , are hy how u neen my Canis familiaris is brown electromagnetic radiation of high frequence and have high energy, therefore they can go at the velocity of visible radiation and can cover 100s to 1000s of metres in air before their energy has subsided. Gamma rays, unlike alpha atoms, can go through through many sorts of stuffs, including human tissue. Very heavy stuffs, such as lead, are normally used as screening to decelerate or halt gamma beams ( 15 ) . Gamma rays can go a wellness jeopardies when being absorbed by populating tissue because they are a signifier of ionising radiation ( 16 ) .
Question 2 i?? Why do isotopes of elements spontaneously undergo radioactive decay?
In the elements, their nuclei undergo experience some of the i??stressi?? in the atom and undergo radioactive decay order to let go of some of the “ stressi?? . At a certain point, the karyon of an atomor atoms gets excessively big to prolong all of these protons and neutrons. The atom so relieves the i??stressi?? and radioactive decay occurs ( 17 ) .
Question 3 – What component do substances go one time they have undergone radioactive decay?
When radioactive elements undergo assorted types of radioactive decay, until a stable atomic karyon arises as a girl merchandise ( 18 ) , and besides when the sequence of alpha and beta decay until they eventually become stable isotopes, they form lead.
As seen in the illustration provided in the Table, all of the natural series terminate with isotopes of lead, i.e. , lead-206, lead-207, and lead-208. Second, all of these are stable isotopes of the component and no farther radioactive emanation hence takes topographic point ( 19 ) .
Showing of Radioactive Decay of Elementss
Question 4 – Explanation of the term i??Half-lifei??
i??Half-lifei?? is the period of clip it takes for a substance undergoing decay to diminish by half, or the clip it takes for one-half of the sample to disintegrate ( 20 ) . It is the clip required to change over one half of a reactant to merchandise. The term is normally applied to radioactive decay where the reactant is the parent isotope and the merchandise is a girl isotope ( 21 ) . The original name given to i??half-lifei?? was i??half-life periodi?? in the 1950i??s ( 22 ) . To forestall the chemical from remaining for good within the norm you can put a decay rate. This sets a period of clip over which the chemical sum will easy drop down towards nothing ( 23 ) .
i??Half-livesi?? are normally used to depict undergoing exponential decay, for illustration radioactive decay, where the i??half-lifei?? remains changeless during the whole life of the decay. The i??half-lifei?? can besides be defined for non-exponential decay processes so in these instances the half life varies throughout the decay procedure. The converse of half life is duplicating clip ( 24 ) .
The chemical half-life cistron defines the decay rate of all the chemicals inside their norm. Each chemical has a value runing from 0 through to 255, stand foring the sum of substance within the norm ( 25 ) .
Table 2. Half life of the some substances
Question 5 – Carbon Dating
Radiocarbon dating was developed in 1949 by Willard Libby and his co-workers at the University of Chicago. He was so awarded the Nobel Prize in chemical science in 1960 for his find. His first presentation to turn out carbon 14 dating was done when Libby accurately estimated the age of wood from an ancient Egyptian royal flatboat for which the age was known from historical paperss. Consequently C dating was developed by a squad led by Willard Libby. He introduced the Libby half life which was the carbon-14 half life of 5568i??30 old ages. Subsequently a more accurate figure was introduced, the Cambridge half life, of 5730i??40 old ages ( 28 ) .
Radiocarbon dating, or C dating, is a radiometric dating method that uses the of course happening radioisotope carbon-14 ( 14C ) to find the age of carbonous stuffs up to about 58,000 to 62,000 old ages of age ( 29 ) . Carbon dating is a assortment of radioactive dating which is applicable merely to affair which was one time living and presumed to be in equilibrium with the ambiance, taking in C dioxide from the air for photosynthesis ( 30 ) . The low activity of the carbon-14 bounds age findings to the order of 50,000 old ages by numbering techniques. That can be extended to possibly 100,000 old ages by gas pedal techniques for numbering the carbon-14 concentration. ( 31 ) . Cosmic beam protons blast karyon in the upper ambiance, bring forthing neutrons which in bend bombard N, the major component of the ambiance. This neutron barrage produces the radioactive isotope carbon-14. The radioactive carbon-14 combines with O to organize C dioxide and is incorporated into the rhythm of life things ( 32 ) .
The most frequent utilizations of carbon 14 dating is to gauge the age of organic remains from archeological sites. When workss, during photosynthesis, add C dioxide into organic stuff, they incorporate a measure of 14C which matches the degree of isotopes in the ambiance. Then as workss die or are consumed by organisms i.e. worlds, the 14C fraction of the organic stuff lessenings at a fixed exponential rate due to the radioactive decay of 14C. The staying 14C fraction of the decayed works is compared to that expected from atmospheric 14C. This comparing allows the age of the sample to be estimated ( 33 ) .
The carbon-14 signifiers at a changeless rate, hence by mensurating the radioactive emanations from the once-living affair and comparing its activity with the equilibrium degree of life things, a measuring of the clip elapsed can be made ( 34 ) .
Question 6 – What is a Geiger Counter?
A Geiger Counter, besides known as Geiger-Mi??ller Counter, is a atom sensor that measures ionising radiation and is besides used to observe if objects emit atomic radiation.
It is an inert gas-filled tubing which briefly conducts electricity when a atom or photon of radiation makes the gas conductive. Normally He, Ne or Ar with halogens are added. Then the tubing amplifies this conductivity by a cascade consequence and outputs a current pulsation, which is so frequently displayed by a needle or lamp and/or hearable chinks.
Some Geiger Counters can be used to observe gamma radiation because the denseness of the gas in the setup is normally low, leting most high energy gamma photons to go through through undetected. The sensitiveness can be lower for high energy gamma radiation because lower energy photons are easier to observe, and are better absorbed by the sensor. Gamma photons interact with the walls bring forthing high-energy negatrons which are so detected. Even though a Na iodide scintillation counter is a better device for observing gamma beams, Geiger sensors are still more favorable due to their low cost and hardiness.
A fluctuation of the Geiger tubing is used to mensurate neutrons. This is when the B trifluoride and a fictile moderator is used to decelerate the neutrons inside the sensor. This creates an alpha atom inside the sensor and therefore neutrons can be counted ( 35 ) .
Question 7 – Nuclear Fission
Nuclear fission is the dividing up of atom ( 36 ) into two or more smaller karyon plus some byproducts ( 37 ) , including free neutrons and lighter karyon, which may finally bring forth photons ( in the signifier of gamma beams ) ( 38 ) . The strong atomic force adhering energy causes the fission to let go of significant sums of energy ( 39 ) .
This atomic fission can happen when a karyon of a heavy atom captures a neutron or can even go on spontaneously. The atomic fission splits into several smaller fragments, these fragments, or besides called fission merchandises, are equal to half the original mass. The staying mass has been converted into energy harmonizing, to Einstein ‘s equation. ( 40 ) .
Nuclear fission merchandises are radioactive and take a long clip to disintegrate, doing atomic waste jobs. This has lead to arguments on whether to utilize atomic fission as an energy beginning due to the atomic waste accretion. Nuclear fission produces energy for atomic power Stationss and atomic bombs because certain substances called atomic fuels undergo fission when struck by free neutrons and in bend generate neutrons when they break apart. This causes a self-sufficient sustaining concatenation reaction that releases energy at a controlled rate in a atomic reactor or at a really rapid uncontrolled rate in a atomic arm ( 41 ) .
Question 8 – Critical Mass
Critical mass is the smallest mass of a fissile stuff that will prolong a atomic concatenation reaction at a changeless degree ( 42 ) or back up a self-sufficient atomic chain. ( 43 ) . It is besides seen as the sum of a substance that is necessary for a atomic concatenation reaction to get down ( 44 ) .
Critical mass could besides be seen as when fission events occur in the mass of fissionable stuff, neutrons are released. Some neutrons are captured and lead to fission, while others escape the mass or are absorbed by some other sort of karyon. If the expected figure of neutrons, which triggers new fissions, is less than one, a atomic concatenation reaction may happen doing iti??s size to diminish. This is known as criticalness. Though, if the expected figure of neutrons is greater than one, the concatenation reaction will increase exponentially and the constellation is called a critical mass ( 45 ) .
Question 9 i?? Difference between Nuclear Fusion and Nuclear Fission
Nuclear i??fissioni?? is the splitting of a monolithic atom into two or more smaller 1s, while atomic i??fusioni?? is the fusing of two or more igniter atoms into a larger one ( 46 ) . In simple footings, atomic fission splits a monolithic component into fragments, let go ofing energy in the procedure. While atomic merger joins two light elements, organizing a more monolithic component, and let go ofing energy in the procedure ( 47 ) Nuclear fission reaction doni??t usually occur in nature unlike atomic merger which occurs in stars, such as the Sun.
A farther difference is that for atomic fission to happen, the critical mass of the substance and high-velocity neutrons are required, while for atomic merger, high denseness and temperature environment is required. The atomic merger produces few radioactive atoms compared to atomic fission where many extremely radioactive atoms are produced.
The energy ratios between merger and fission is besides different because the energy released by atomic merger is three to four times greater than the energy released by fission. Although, the energy released by atomic fission is a million times greater than that released in chemical reactions. This is due because atomic fission requires small energy to divide two atoms, compared to atomic merger where highly high energy is required to convey two or more protons near enough that atomic forces overcome their electrostatic repulsive force ( 48 ) .
Question 10 i?? Why are merger reactions non used in atomic reactors?
Nuclear reactors are big machines that control atomic concatenation reactions while let go ofing heat at a controlled rate. If an uncontrolled atomic reaction is in a atomic reactor, it can potentially ensue in widespread taint of air and H2O with radiation for 100s of kilometers around the margin ( 49 ) . Nuclear merger is much more hard to accomplish than atomic fission, which is what current atomic power engineering is based on. Second, it is besides hard to make a sustainable and stable atomic merger reaction and make a reaction that has a greater end product than input. If this was possible, it would give the Earth limitless engineering as it would hold an energy end product similar to that of a star ( 50 ) .
Third, even though merger reactors doni??t have the fission merchandise waste disposal job of fission reactors, merger reactors generate big figure of fast neutrons, taking to big measures of radioactive byproducts ( 51 ) .
In drumhead atomic fission is more governable than atomic merger ; fission is easier to make and prolong than merger and merger generates big measures of radioactive byproducts despite non holding the fission merchandise waste disposal issues ( 52 ) .
Question 20 i?? How is the fission reaction of the atom bomb controlled?
The atomic bomb is normally heavier than the critical mass. The radioactive stuffs in the bomb are kept apart and are less than the critical mass until they collide into each other ( 53 ) . When atomic merger begins, merely one neutron is released and is free to strike an atom of U-238, this so gives rise to three more neutrons. These three neutrons work stoppage another three atoms of U-238 and this releases three more neutrons from each atom, doing a sum of nine neutrons. This procedure is easy initiated and it explains why the atom bomb does non blare off instantly ( 54 ) .
Another method could be to roll up adequate Pu inside the bomb, and if thick plenty, the neutrons can non get away without hitting another karyon, and the concatenation reaction will get down. Then by infixing particular today is a truly nice twenty-four hours adult male neutron-absorbing stuff in between parts of the Pu the rate at which the concatenation reaction returns can be controlled, ensuing in a ‘slow burn ‘ alternatively of an detonation ( 55 ) .
To command the fission reaction, rods made of Cd or B are suspended between the fuel rods. These rods can be raised or lowered and therefore look into the reaction by absorbing the right figure of neutrons. Hence they are called i??control rodsi?? . When the control rods are wholly inserted into the fuel, i.e. , inside the reactor, all the neutrons are absorbed and the reaction does non get down.
These rods are so easy raised boulder clay they absorb the right figure of neutrons and therefore go forthing behind merely adequate neutrons to prolong the concatenation reaction. That is, when the control rods absorb two neutrons go forthing behind one neutron to convey about farther fission reaction we say that the reactor has i??attained criticalityi?? . At this phase, the figure of atoms acquiring fissioned in one second is changeless which means that energy is generated at a changeless rate ( 56 ) .
Question 21 i?? Two Nipponese metropoliss bombed
The two Nipponese metropoliss which were bombed during World War II were Hiroshima and Nagasaki. On the 6th August 1945, the United States dropped an atomic bomb on Hiroshima, Japan. This atomic bomb was tantamount of 20,000 dozenss of TNT, killing 10s of 1000s of civilians ( 57 ) . Then on the 15th August 1945, three yearss subsequently to the old bombardment, the United States dropped another bomb on Nagasaki, Japan. Finally stoping World War II after Japan surrendered in 1945
( 58 ) ( 59 ) .
Question 22 – Death Rate
When these atomic bombs exploded they caused short and long term effects. Within the first two to four months of the bombardments, the acute effects killed 90,000i??166,000 people in Hiroshima and 60,000i??80,000 in Nagasaki. Most of these deceases occurred on the first twenty-four hours. Hiroshimai??s Health Department suspected that of the people who died on the twenty-four hours of the detonation 60 % died from flash or fire Burnss, 30 % from falling dust and 10 % from other causes. During the undermentioned months after the bombs 20-30 % died from flash Burnss or consequence of Burnss, 15-20 % died from radiation illness, and 50-60 % died from other hurts and unwellnesss. Since the bombardments 231 people, who were under observation, died from leukemia and 334 people died from malignant neoplastic disease due to the exposure to radiation released by the bombs. In both metropoliss, most of the dead were civilians ( 60 ) .
Question 23 i?? How the Hydrogen Bomb plants and how it differs from the Atom Bomb
In an atomic bomb, the energy beginning is a mass of radioactive stuff such as U or Pu. This stuff is really unstable due to the atomi??s atomic being ready to fall apart or
i??decayi?? at the slightest jog, and explode by let go ofing unnecessary energy and excess neutrons. In the undermentioned diagram, the Pu ( B in Diagram 1 ) is given that jog by the outer shell of TNT ( A in Diagram 1 ) , which explodes all around it. ( 1 )
Diagram 1: Atomic Bomb Diagram 2: Hydrogen Bomb
In comparing, the H bomb non merely releases much more energy, utilizing a procedure called ‘nuclear merger ‘ , but it is non triggered by TNT, instead it is i??triggeredi?? by an atomic bomb ( 61 ) .
The cardinal nucleus ( B in Diagram 2 ) is a mass made up of atoms which are both isotopes of H, called heavy hydrogen and tritium. These are both H bombs made up of excess neutrons in each karyon. Small atomic bombs are placed around the exterior, this causes the heavy hydrogen and tritium to be squeezed into a really heavy mass. This procedure is called atomic merger, and it releases great measures of energy. As the nucleus of the bomb explodes, it causes the bomb shell ( C in Diagram 2 ) , which is made from U, to undergo fission, making even more energy. Overall, an atomic bomb sets off a merger bomb, which besides triggers another atomic bomb making a H bomb ( 62 )
In drumhead, the differences between the atomic bomb and the H bomb are that the atom bombs work on the rule of i??atomic fissioni?? ( dividing the atomic karyon ) , while H bombs work on the rule of i??atomic fusioni?? ( uniting atomic karyon ) . Second, the H bomb is 100s or 1000s of times more powerful than the atom bomb and the H bomb uses an atom bomb as a trigger ( 63 ) . Third, the H bomb leaves behind no radiation and the activation energy is enormous. Whilst in comparing the atomic bomb leaves behind monolithic after effects and requires a important less sum of energy to happen ( 64 ) .
Question 24 i?? Health Hazards Associated with Radiation
There are many wellness jeopardies caused by radiation. In the atomic bomb the radioactive stuffs which decay spontaneously produce ionizing radiation which remove negatrons from atoms or interrupt chemical bonds. Any populating tissues in the human organic structure can be damaged by ionizing radiation in a alone mode. Then the organic structure attempts to mend the damaged tissue, sometimes the harm can non be repaired or is excessively terrible or widespread to be repaired. Besides, errors made in the natural fix procedure can take to cancerous cells.
Bing exposed to radiation causes different sorts of wellness effects. In general, the sum and continuance of radiation exposure affects the badness or type of wellness effects. There are two wide classs of wellness effects: stochastic and non-stochastic.
Stochastic effects are associated with long-run, low-level ( chronic ) exposure to radiation. The increased degrees of exposure to radiation do these wellness effects to be more likely to happen but make non act upon the type or badness of the consequence. Cancer is considered the primary wellness consequence from radiation exposure because malignant neoplastic disease is the uncontrolled growing of cells. This occurs when there is harm happening at cellular or molecular degree leting for the uncontrolled growing of cells i.e. malignant neoplastic disease.
Other effects occur because radiation can alter the Deoxyribonucleic acid that ensures cell fix and replacing produces a perfect transcript of the original cell. This is called i??mutationi?? and can be teratogenic or familial. Teratogenic mutants are caused by exposure of the foetus in the womb and affects merely the person who was exposed. Familial mutants are passed on to the progeny.
While non-stochastic effects occur when there is exposure to high degrees of radiation and effects become more terrible as the exposure increases. These short-run, high-ranking exposure is referred to as ‘acute ‘ exposure. Unlike malignant neoplastic disease, wellness effects from ‘acute ‘ exposure to radiation normally appear rapidly. These effects include Burnss and radiation illness. Radiation illness is besides called ‘radiation poisoningi?? , which causes premature aging or even decease within two months if over exposed. The symptoms of radiation illness include: sickness, failing, hair loss, skin Burnss or diminished organ map ( 65 ) .
Question 25 i?? Medical Applications for Cancer Treatment, X-rays and Radioactive Tracers
a ) Cancer Treatment
Radiation is used in malignant neoplastic disease intervention to bring around malignant neoplastic disease whilst keeping acceptable map and cosmetics. Radiation can besides be used entirely or combined with chemotherapy and/or surgery. Radiation is recommended when the patient needs it to relieve hurting after the tumour has spread or until it will be most good for the patient ‘s comfort. Radiation therapy can besides be used in the intervention for assorted tegument malignant neoplastic diseases, malignant neoplastic disease of the oral cavity, rhinal pit, throat and voice box ; encephalon tumours and many gynecological, lung malignant neoplastic diseases, and prostate malignant neoplastic diseases. Radiation therapy plays a prima function in concurrence with surgery and/or chemotherapy in chest malignant neoplastic disease, intestine malignant neoplastic disease, vesica malignant neoplastic disease, Hodgkin ‘s disease, leukaemia and lymphomas, thyroid malignant neoplastic disease and childhood malignant neoplastic diseases ( 66 ) .
B ) X raies.
Radiation therapy plant by destructing cells, either straight or by interfering with cell reproduction utilizing high-energy X raies, negatron beams or radioactive isotopes. This is when a radiated cell efforts to split and reproduce itself, it fails to make so and dies in the effort. In other instances, normal cells are able to mend the effects of radiation better than when there are malignant and other unnatural cells, hence normal cells are able to retrieve from exposure to radiation and survive better than malignant cells. If radiation is applied in the right part and in the right sums so the malignant neoplastic disease dies and the patient is good once more because the normal tissue survives. If non all malignant neoplastic disease cells are killed so the malignant neoplastic disease may reproduce and further radiation may needed but in lesser measures because the normal tissues are less able to defy the effects of farther radiation.
Even though there is grounds of radiation exposure during medical x-ray processs, the benefits of holding an X ray for a patient showing some medical symptom outweigh the hazard of the radiation impacting the individual. The X raies are known as i??ionizing radiationi?? which means that the radiation is of a high plenty energy to interrupt chemical bonds and therefore has the possible to be harmful to populating beings. When these bonds are broken there is, unluckily, the possible to do harm to cell nuclei.
However, this same state of affairs makes X raies every bit effectual as malignant neoplastic disease intervention in the signifier of radiation therapy. Another benefit is that x-rays allow people to see the construction of internal variety meats and castanetss and measure without the demand for surgery. The radiation know to happen during an x-ray is believed to be low and harmful effects are straight relative to the sum or dose the patient endures ( 67 ) .
degree Celsius ) Radioactive Tracers
A radioactive tracer, besides called a i??radioactive labeli?? , is a substance incorporating a radioisotope and a radioactive atom to let easier sensing and measurement.. A radioisotope is an isotope that has an unstable karyon and that stabilizes itself by spontaneously breathing energy and atoms. They were ab initio invented by Quinn Hanson and subsequently developed by George de Hevesy and are used to mensurate the velocity of chemical procedures and to track the motion of a substance through a natural system such as a cell or a tissue. ( 68 )
The simplest radioactive tracer surveies show the tagging of a biological entity with a radioactive isotope ( radioisotope ) . The entity is so tracked by following the radiation from the isotope. Largely in biological tracer experiments, the radio-isotope is placed into the system and iti??s radiation is measured with Geiger-Mi??ller Counters or scintillation sensors. Highly soft ( low-intensity ) radiations can be detected by the usage of photographic movie. ( 69 )
The radioactive tracer is relied on to a great extent by the medical profession for direct radiation Fieldss and radioactive isotopes for placing and handling disease and are used extensively to prove new drugs and behavior research into remedies for disease. ( 70 )
Radioactive stuffs consist of radionuclides and radioactive isotopes. A radionuclide is any type of radioactive stuff, including elements and the isotopes of elements. An isotope of an component is a peculiar atomic “ version ” of it. Radionuclides are used in more than 11 million atomic medical specialty processs every twelvemonth in the United States. Examples of radioactive tracers in medical processs are bone scans that can observe the spread of malignant neoplastic disease six to eighteen months sooner than X raies and kidney scans are much more sensitive than X raies or ultrasound in to the full measuring kidney map ( 70 ) . They besides are used in 100 million research lab trials on organic structure fluid and tissue specimens. Isotopes are atoms of the same component with different atomic constructions.
Radioactive tracers are used chiefly for bone scans, kidney scans. Radioactive the sky is bluish today isotopes and radioactively labeled molecules are used and it is a really bad furniture as tracers to place unnatural bodily procedures. When a patient is injected with a radioactive component, a particular camera can take images of the internal workings of the organ.