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PS Ch. 18 Review
DHS PS CH18 Review
| Question | Answer |
|---|---|
| What is composed of protons and neutrons and comprises most of the atom's mass? | nucleus |
| What causes protons and neutrons to be attracted to each other in the nucleus? | strong force |
| Describe the characteristics of the strong force: | 1). one of the four basic forces 2). holds proton and neutrons together 3). 100x stronger than electric force 4). acts only over a short distance |
| When is the strong force the most powerful? | when neutrons and protons are closely packed together or touching |
| To what degree are protons and neutrons held by the strong force in a large nucleus? | less tightly |
| What force works against the strong force? | the electric force |
| When will the nuclues decay? | when the strong force is not large enough to hold a nucleus together tightly. |
| What are the four fundamental forces? | 1). strong force 2). electromagnetic force 3). weak force 4). gravity |
| Which is the strongest of the four fundamental forces? | the strong force |
| Which is the weakest of the four fundamental forces? | gravity |
| When nucleuar decay happens because the strong force is not large enough to hold the nucleus together this is called? | radioactivity |
| What are atoms of the same element with varying numbers of neutrons called? | isotopes |
| A nucleus with too many or too few neutrons compared to protons is considered? | radioactive |
| The Atomic number is equal to? | the number of protons in an atom |
| The Mass number is equal to? | the number of protons and neutrons in a nucleus |
| Who is credited with discovering radioactivity? | Henri Becquerel in 1896 |
| How did Henri Becquerel make his discovery? | He spilled uranium salt on a photographic plate. When the plate was developed, dark spots remained where the clumps fell. |
| Who discovered Polonium and Radium? | Marie & Pierre Curie in 1898 |
| Isotopes have? | the same number of protons, but a different number of neutrons |
| The size of a nucleus compared to the size of an atom could be compared to? | a marble in the middle of a stadium |
| Protons do not repel each other in the nucleus because of the? | strong force |
| All elements with an atomic number over 83 are considered to be? | radioactive |
| What happens in a radioactive nuculeus? | the electric force overpowers the strong force releasing mass and energy. |
| What could you describe the strong force as? | a short-range force |
| A transverse wave consisting of vibrating electric and magnetic fields is what type of wave? | electromagnetic wave |
| A type of nuclear radiation made of 2 protons and 2 neutrons si called a? | alpha particle |
| The process of changing one element to another through nuclear decay is? | transmutation |
| A type of nuclear radiation that consists of an electron emitted from the nucleus? | beta particle |
| A type of nuclear radiation that consists of electromagnectic waves is a? | gamma ray |
| The amount of time it takes for half the nuclei in a sample of isotopes to decay is? | half life |
| What happens when an unstable nucleus decays? | the strong force is overpowered by the electric force or it gives off particles and energy |
| What are three types of nuclear radiation? | alpha particles, beta particle and gamma rays |
| What does it take to stop an alpha particle? | a sheet of paper |
| When can alpha particles be dangerous? | if they are released by radioactive atoms inside the human body through breathing or ingestion. |
| Explain how smoke detectors use alpha particles: | smoke detectors give off alpha particles which ionize the air allowing current to flow. When smoke particles are present, they absorb the ions breaking the circuit |
| Explain how the atomic and mass numbers of an element change after alpha decay: | It loses 2 protons and 2 neutrons decreasing the atomic number by 2 plus the mass number by 4. |
| Describe what occurs during beta decay: | a neutron decays into a proton and emmits an electron |
| Explain how the atomic and mass numbers of an element change after beta decay: | because it gains one more proton, it changes to an element with one greater atomic number |
| What does it take to stop beta particles? | a sheet of aluminum foil |
| When are gamma rays emitted? | whenever alpha or beta decay happens |
| What does it take to stop a gamma ray? | lead or concrete |
| What is a daughter nucleus? | the nucleus left after the isotope decays |
| Radioactive dating uses the half-life of different radioactive materials to test the ____ of a sample. | age |
| Radioactivity can be harmful and cause disease because it affects? | cells (biological cells are large and delicate) |
| Gamma particles _____. | have no mass and no charge |
| When a neutron turns into a proton in a nucleus, what sort of particle is emitted? | beta |
| The proocess in which an atom loses radiation and becomes another element is known as? | transmutation |
| Which form of nuclear radiation is used in smoke detectors? | alpha particles |
| Alpha particles contain? | two protons and two neutrons |
| When particles and energy are released from a decaying nucleus it is called? | radioactivity |
| In cloud chambers, which form of radiation leaves short, thick trails of droplets? | alpha particles |
| Nuclear radiation can cause the electroscope to? | lose its charge |
| Which device holds a superheated liquid, which doesn't boil because the pressure is so high? | bubble chamber |
| In cloud chambers, which form of radiation leaves long, thin trails of droplets? | beta particles |
| What are sources of background radiation? | soils, rocks, atmosphere, or any other natural thing. |
| One type of radioactive device that directly indicates the intensity of radiation with a clicking sound that increases in frequency as more radiation is present is a(n) _______. | Geiger counter |
| Electroscopes can detect radioactive particles when alpha particles remove ______from the electroscope? | electrons |
| Cloud chambers detect radioactive particles when they make what in a cloud? | ions |
| What source makes up the most background radiation that humans are exposed to? | radon |
| What strategy would prevent a person from being exposed to background radiation? | there is no strategy that can prevent it |
| What detects alpha or beta particles be means of a trail of condensed vapor? | cloud chamber |
| What detects radioactive particles by means of a bubble trail in a superheated liquid? | bubble chamber |
| What can measure charged particles in the air by first giving it a charge? | electroscopes |
| What directly measures radioactivity by producing an electric current when radiation is present? | geiger counter |
| Where is radon gas produced? | in the Earth's crust, from cosmic rays, and rom radioactive isotopes in the body |
| What is the process of splitting a nucleus into two nuclei with smaller masses? | nuclear fission |
| What is an ongoing series of fission reactions called? | chain reaction |
| What is critical mass? | the amount of fissionable material required to continue a reaction at a constant rate |
| When two nuclei with low masses are combined to form one nucleus of larger mass it is called? | nuclear fusion |
| When does nuclear fusion happen? | only when nuclei are moving fast enough to get close to each other |
| What is the difference between fission and fusion? | fission splits a larger nucleus into two smaller ones; fusion takes two smaller nuclei and combines them to form a larger one |
| What happens when a neutron hits a uranium-235 nucleus? | the uranium splits tinto two smaller nuclei |
| When fission occurs a smaller amount of mass comes up missing. Where did it go? | a mall amount of mass can be converted to an enormous amount of energy E = mc2 |
| How are crital mass and chain reactions related? | if less than the critical mass of a material is present, a chain reaction will NOT occur |
| How does fusion occur on the sun? | H nuclei combine to form He nuclei releasing lots of energy |
| What isotope is used to diagnose thyroid problems? | I-131 |
| What are the two ways that cancer can be treated with radioactivity? | 1). radiation can be placed near cancer cells causing them to die or stop growing 2). Intense beams of gamma rays from Co-60 can be focused on the tumor |
| Only nuclei with _______ atomic numbers can undergo fission? | large |
| In the Sun, hydrogen atoms fuse together to form? | He-3 |
| During nuclear fission, a nucleus _______. | divides or splits |
| Radioactive materials can be used in medicine as ______ by injecting a patient and then tracking the course of the isotopes. | tracers |
| What is the term for an ongoing series of nuclear reactions? | chain reaction |
| The ________ of a reaction is the amount of fissionable material to make each reaction produce one more? | critical mass |
| When two smaller nuclei come together, it is called? | fusion |
| What initiates nuclear fission of a uranium-235 nucleus? | being struck with a neutron |
| The most penetrating type of radiation is the? | gamma ray |
| A helium nucleus with tow protons and two neutrons is called a? | alpha particle |
| When a strong force is not sufficient to hold unstable nuclei together permanently, ___? | the nuclei decay |
| Negatively charged paticles emitted from a nucleus at a high speed are? | beta particles |
| The discovery of radioactivity by Henri Bequerel involved a? | photographic plate |
| The process by which nuclei having low masses are united to form nuclei with larger masses is? | nuclear fusion |
| What are the three types of nuclear radiation in increasing order of penetrating power? | alpha, beta, gamma |
| For lighter elements to be stable, the neutron-to-proton ratio must be? | 1:1 |
| Radioactive tracers are useful in? | determining medical problems |
| Both fusion reactions and a fission reaction produce? | energy |
| Isotopes have? | the same number of protons, but a diffeent number of neutrons |
| You could describe the strong force as what type of force? | short-range |
| In a radioactive nucleus, the electric force does what to the strong force? | overpowers |
| Elements with an atomic number over 83 are? | radioactive |
| For heavier elements to be stable, the neutron-to-proton ratio must be ______ to be stable. | 3:2 |
| In 1938, Otto ____ and Fritz ______ found that when a neutron strikes a U-235 nucleus, it divides. | Hahn and Strassmann |
| Which is more powerful, fission or fusion? | fusion is much more powerful |
| 1 g of mass can be converted into _________ joules. | 100 trillion |
| A ___ scan can be used to measure brain activity. | PET scan or Positron Emission Tomography |
| With each breath, you inhale ______ C-14 atoms. | 3 million |
| What is the half-life of a 100.0g sample of nitrogen-16 that decays to 12.5 g in 21.6 s? | 7.2 seconds |
| If the half-life of iodine-131 is 8.10 days, how long will it take a 50.00 g sample to decay to 6.25 g? | 24.3 days |
| Potassium-42 has a half-life of 12.4 hours. How much of an 848 g sample will be left after 62.0 hours? | 26.5 g |
| Radon is the ________ leading cause of lung cancer in the United States | second (smoking is the first) |
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basmith
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