Chemistry Chapter 25 Nuclear Chemistry Notes/Questions

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Nucleon
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proton + neutron
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In nuclear chemistry, an atom is referred to as a what? what is it identified by?
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nuclide; by the number of protons and neutrons in its nucleus.
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True/False: The mass of an atom does not equal the sum of the masses of the protons, neutrons, and electrons in an atom.
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True
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What is the difference between The mass of an atom does not equal the sum of the masses of the protons, neutrons, and electrons in an atom called?
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mass defect
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What causes the mass defect?
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The mass defect is cause by the conversion of mass to energy upon the formation of the nucleus.
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nuclear binding energy(energy released when a nucleus is formed from nucleons or energy required to break apart the nucleus).
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the mass defect can be converted to energy using Einstein’s Equation E=mc^2 and is called ___.
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What does Binding energy a measure of?
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Binding energy is a measure of the stability of a nucleus.
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True/False: Dalton thought that atoms were unchangeable.
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True
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What two scientists in the late 1800’s began to notice that some elements spontaneously emitted particles and energy?(HINT: 2 People) Which one of the scientists named the process by which materials emit particles and energy (radioactivity).
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Marie Curie and Becquerel; Marie Curie
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Radioactivity
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process by which materials emit particles and energy.
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What are the emissions of radioactivity called?
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radiation
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What did scientists discover that radioactive elements did after emitting radiation?
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they changed into other elements
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Was Daltons thoughts on atoms correct?(HINT: He thought they were unchangeable)
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No
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What is it called when: some nuclei are unstable and gain stability by emitting radiation through process called___?
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Radioactive decay
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True/False: Nuclear reactions differ from chemical reactions?
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True
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What happens in a chemical reaction?
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atoms tend to attain stability by transferring or sharing electrons. The nuclei remained unchanged.
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What happens in a nuclear reaction?
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In nuclear reactions, the nuclei of unstable isotopes, called radioisotopes, gain stability by undergoing change. These changes are accompanied by the emission of large amounts of energy.
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What does not effect a nuclear reaction?
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temperature, pressure, or catalysts.
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True/False: Can nuclear reactions be speeded up, slowed down, or turned off.
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False, they cannot.
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Are Radioisotopes chemically different from other isotopes of the same element?
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No, Radioisotopes are not chemically different from other isotopes of that element. It depends on the electron structure of an atom, not its nuclear make up.
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What does chemical reactivity depend on?
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It depends on the electron structure of an atom, not its nuclear make up.
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What does nuclear decay illustrate?
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Nuclear decay illustrates the interconnected nature of matter and energy.
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(X) How is matter related to energy?
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Matter is related to energy according to the equation E=mc^2 where c is a constant equal to the speed of light.
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What are the different types of radiation?
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Alpha particles, Beta particles, Positron emission, Electron capture, and Gama rays
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Alpha Particles(HINT: 6 bullet points)
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1. Helium-4 nucleus 2. Contains 2 protons and 2 neutrons ….(4/2 He) 3. Ejected from nucleus 4. +2 charge 5. Restricted almost entirely to very heavy nuclei 6. Low penetrating power because of large mass and charge.
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What does it take to shield a alpha particle?
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sheet of paper or surface of your skin will shield them.
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True/False: it is dangerous to ingest a alpha particle
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True, Dangerous when ingested because they will travel short distance to penetrate tissue and cause damage.
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Alpha Decay
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A new element, radon, is created as a result of the alpha decay of the unstable radium-226 nucleus
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Nuclear equation
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atomic and mass numbers are shown.
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Beta Particles(HINT: 6 bullet points)
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1.High-energy electrons …..(0/-1e) 2. -1 charge 3. Emitted from the nucleus when neutron is converted to proton and electron. 4. Atomic # (# protons) increases by one and mass # (#protons + # neutrons) stays the same. 5. More penetration than alpha particle because it has less charge and less mass. 6. Can penetrate paper, but stopped by aluminum foil and thin pieces of wood.
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Positron emission(Hint: 3 bullet points)
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1. Same mass as an electron, but has a positive charge, and is emitted from the nucleus during some kinds of radioactive decay. 2. Proton can be converted into a neutron by emitting a positron. 3. Emitted by unstable nuclei with too many protons for the number of neutrons.
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What is the antiparticle for an electron?
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Positron (emission)
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Electron capture(Hint:2 bullet points)
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1. An inner orbital electron is captured by the nucleus of its own atom. 2. Inner orbital electron combines with a proton to form a neutron.
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Gamma Rays(HINT: 7 bullet points)
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1.High-energy electromagnetic waves emitted from the nucleus as it changes from an excited state to a ground energy state. …..(0/0y) 2. Possesses no mass and no electrical charge. 3. usually accompany alpha and beta radiation. 4. Account for most of the energy lost during radioactive decay. 5. Extremely penetrating and can be very dangerous. 6. Penetrate paper, wood,, and human body. 7. Stopped-although not completely-by several meters od concrete or several cm of lead.
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Is the percentage of different nuclei that are stable small or large?
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Small, Only 264 of the more than 1500 different nuclei are stable and do not decay or change.
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The stability of a nucleus depends on a ____to____ ratio.
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The stability of a nucleus depends on the [neutron]-to-[proton] ratio.
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*(stared)As the number of protons increases, the number of neutrons_____.
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As the number of protons in the nucleus increases, there is a need for neutrons to counteract the effect of proton-proton repulsion.
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What type of nuclei with a low atomic numbers (up to 20) have approximate equal numbers of protons and neutrons?
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Stable nuclei with low atomic numbers (up to 20) have approximately equal numbers of protons and neutrons.
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For nuclei with higher atomic number what happens to the number of neutrons to protons?
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For nuclei with higher atomic numbers, the number of neutrons exceeds the number of protons.
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What is the band of stability?
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A neuron-versus-proton plot of all stable nuclei forms a pattern called the band of stability in which all stable nuclei are found. the band ends at element 83.
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What element does the band of stability end at? What property do elements after the end of the band have?
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The band ends at element 83. All nuclei that have an atomic number greater than 83 are radioactive.
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What determines the type of decay that occurs?
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The neutron-to-proton ration helps determine the type of decay that occurs.
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Every radioisotope has a characteristic rate of decay measured by its _____.
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Every radioisotope has a characteristic rate of decay measured by its half-life.
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True/False: No two radioactive isotopes decay at the same rate.
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True;No two radioactive isotopes decay at the same rate-it is unique to that isotope.
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True/False: Half-life’s can only last a short period of time.
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False; Half-lives can be as short as a fraction of a second or as long as billions of years.
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Half-life
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is the time required for half the atoms of a radioactive isotope to decay.
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After each half-life,____ of the existing radioactive atoms have decayed into atoms of a new element.
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After each half-life, half of the existing radioactive atoms have decayed into atoms of a new element.
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What are two examples of Half-life’s being used?
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1. (AGE)Scientist use the half-lives of some radioisotopes found in nature to determine the age of ancient artifacts. 2. (MEDS)Many artificially produced isotopes have half-lives and can be used in nuclear medicine.
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Can one nuclear reaction be enough to produce a stable nuclide?
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One nuclear reaction is not always enough to produce a stable nuclide.
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What is a Decay series?
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series of radioactive nuclides produced by successive radioactive decay until a stable nuclide is produced.
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What is a Parent nuclide?
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the heaviest nuclide of each decay series.
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What is a Daughter nuclides?
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nuclides produced by the decay of the parent nuclide.
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What is a transmutation?
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The conversion of an atom of one element to an atom of another element is called transmutation.
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Transmutation can occur in what ways/caused by(HINT: 2 bullet points)
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1. by radioactive decay and 2. when particles (protons, neutrons, or alpha particles) bombard the nucleus of an atom.
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True/False: Many transmutations occur in nature.
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True; carbon-14 is produced in the upper atmosphere from nitrogen-14.
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Do transmutations occur in laboratories or in nuclear reactors?
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yes, many others are done in laboratories or in nuclear reactors.;The earliest artificial transmutation was performed by Rutherford in 1919 when he bombarded nitrogen-14 gas with alpha particles emitted by radium to produce fluorine-18 then oxygen-17 plus a proton. (See page 807)
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What are elements above the atomic number 92 called?
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The elements in the periodic table with atomic numbers above 92, the atomic number of uranium, are called the transuranium elements.
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Transuranium elements(HINT: 4 bullet points)
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1. All the transuranium elements undergo transmutation. 2. None of them occur in nature. 3. All of them are radioactive. 4. They have been synthesized in nuclear reactors and nuclear accelerators.
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What are Artificial radioactive nuclides?
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Artificial radioactive nuclides are radioactive nucleides not found naturally on Earth.
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How are Artificial radioactive nuclides made/formed?
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They are made by artificial transmutations – bombardment of stable nuclei with charged and uncharged particles
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What is artificial transmutations?
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bombardment of stable nuclei with charged and uncharged particles.
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Why can neutrons penetrate the nucleus of an atom easily? Is it harder with protons?
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Because they have no charge.; Yes, Charged particles like protons, alpha particles, or other ions are repelled by the nucleus and require great energy to bombard the nucleus. The energy may be supplied by accelerating these particles in the magnetic or electrical field of a particle accelerator.
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What is Nuclear Fission?
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a very heavy nucleus splits into more-stable nuclei of intermediate mass.
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True/False: Nuclear fission produces small amounts of energy.
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False, Fission produces enormous amounts of energy.
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When does nuclear fission occur?
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Nuclear fission can occur spontaneously or when nuclei are bombarded by particles.
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What are the 2 only fissionable isotopes?
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Uranium-235 and plutonium-239 are the only fissionable isotopes.
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What is a Chain Reaction?
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a reaction in which the material that starts the reaction is also one of the products and can start another reaction.
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What is an example of a Nuclear Chain Reaction?
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When fission of an atom bombarded by neutrons produces more neutrons.(what started it produces by it)
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What is Critical mass?
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the minimum amount of nuclide that provides the number of neutrons needed to sustain a chain reaction.
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______ chain reaction provide the explosive energy of atomic bombs.
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Uncontrolled chain reactions provide the explosive energy of atomic bombs.
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What do/are Nuclear reactors?
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use controlled-fission chain reactions to produce energy or radioactive nuclides.
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Nuclear power plants use____ from nuclear reactors to produce electrical energy.
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Nuclear power plants use heat from nuclear reactors to produce electrical energy.
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What is Nuclear Fusion?
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light-mass nuclei combine to form a heavier, more stable nucleus.
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_____Releases more energy per gram of fuel than nuclear fission.
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Nuclear Fusion releases more energy per gram of fuel than nuclear fission.
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How/ give an example of Nuclear fusion.
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In our sun and other stars, four hydrogen nuclei combine at extremely high temperature and pressure to form a helium nucleus with a loss of mass and release of energy. ////The Sun converts 564 million tons of hydrogen to 560 million tons of helium every second with the equivalent of 4 million tons of mass being transformed into energy. According to one author, the energy output in one second by the Sun would supply the entire energy consumption by the United States for 1 million years! Luckily only one two-billionths of the Sun’s energy reaches the Earth! Otherwise we would be cooked to a cinder! It is estimated that it has lost only 1/40,000 of its mass since it became a star.
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_____ ______reactions of hydrogen are the source of energy for the hydrogen bomb.
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Uncontrolled fusion reactions of hydrogen are the source of energy for the hydrogen bomb.
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A _____ _______ is used to provide the heat and pressure necessary to trigger the _______ of the nuclei.
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A fission reaction is used to provide the heat and pressure necessary to trigger the fusion of the nuclei.
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Radiation emitted by radioisotopes is called what?
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ionizing radiation.
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Ionizing Radiation is….?
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is radiation with enough energy to knock electrons off some atoms of the bombarded substance to produce ions (charged atoms).
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What ways can you detect radiation?(HINT: 3 ways)
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1.Geiger counters 2.Scintillation counters 3.Film badges
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What are some uses of Radiation?(HINT: 4 ways)
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1.Neutron activation analysis—(Procedure used to detect trace amounts of elements in samples. Used by museums to detect art forgeries. Used by crime labs to analyze gun-powder residues.) 2.Tracers—(Radioisotopes used in agriculture to test the effects of herbicides, pesticides, and fertilizers. Also monitored in animals that consume the plants.0 3.Radioisotopes used to diagnose medical problems—(Used to detect thyroid problems (Iodine -131). Used to detect brain tumors and liver disorders (technetium -99). Used to detect skin cancer (phosphorus -32). 4.Used to treat diseases—(Radiation therapy is used to kill cancerous cells (gamma rays). Teletherapy -narrow beam of gamma rays is directed at cancerous tissue. Salts of radioisotopes are sealed and implanted in tumors. They emit beta and gamma rays that kill surrounding cancer cells.)

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