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Chapter 20

DHS PS Ch. 20 - Nuclear Reactions (2015/2016)

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 and the electric force causes protons to repel.
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
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 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 while the mass # remains the same.
What does it take to stop beta particles? a sheet of aluminum
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
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
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 directly measures radioactivity by producing an electric current when radiation is present? geiger counter
Where is radon gas produced? in the Earth's crust
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
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 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
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 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
Which is more powerful, fission or fusion? fusion is much more powerful
Radon is the ________ leading cause of lung cancer in the United States second (smoking is the first)
Created by: basmith