Mod H, U4, Les 3 Nucear Reactions Flashcards
(22 cards)
What is a nuclear reaction?
A change that affects the nucleus of an atom.
How do nuclear reactions differ from chemical reactions?
- Nuclear: changes mass fo atoms slightly, changing them into energy that is released during reactions. (Does not occur in chemical reactions)
- Changes the nucleus of atoms. (Chemical reactions don’t) example: can decrease # of protons to change beryllium into lithium)
What does the formula E=mc2 mean?
Energy equals mass times the speed of light squared
What are isotopes?
Atoms with the same # of protons, but different # of neutrons. (They also have different masses) example lithium-6 or lithium-7 (see p. 243
What is radioactive decay?
A nuclear reaction in which an unstable nucleus can give off energy and sometimes particles.
What is nuclear radiation?
The term used to describe the particles and energy given off during radioactive decay
What are the 3 types of radioactive decay?
Alpha decay, beta decay, and gamma decay
Explain Alpha decay.
The release of an alpha particle and energy from a radioactive nucleus. (Alpha particles are made up of 2 protons and 2 neutrons with a charge of 2+). It also reduces the # of protons in the nucleus so it makes a different element.
Explain Beta decay.
A release of a beta particle and energy. (2 types of particles are positrons and electrons and both have a mass of almost zero)
Positron charge = 1+
Electron charge = 1-
What are gamma rays?
High energy radiation with no mass and no charge
Explain gamma decay
When gamma rays are released. It does not change # of particles in nucleus, does not form different elements of isotopes
What are 2 effects of too much exposure to radiation?
Radiation sickness (vomiting, hair falling out, fatigue) Increase cancer risk
What are some examples of how scientists are using radioactive decay in our society?
-kill bacteria, find leaks in pipes, determine age in fossils (carbon), find and treat disease, fight cancer
What is nuclear fission?
A nuclear reaction in which a large, unstable nucleus breaks into 2 smaller nuclei, and releases neutrons. (It changes the nucleus of the atom that breaks apart)
In a fission reaction, the total mass of the end products is less than the mass before the fission reaction began. Why?
The missing mass was transformed to energy
What fuel is used to power nuclear power plants?
Uranium-235
What is a nuclear chain reaction.Explain what happens using Uranium 235.
a continuous series of fission reactions:
A. Neutrons are released, uranium nucleus splits
B. Other nuclei are hit and split too
C. Process happens over and over, energy is released
*This can be controlled like in a power plant or uncontrolled like in a nuclear bomb
Note: see p. 250 to see how an energy power plant controls fission reactions to make electricity.
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What are the disadvantages or using nuclear energy?
When accidents occur: 1. Large amounts of radioactive materials can be released into the atmosphere 2. Radioactive materials can contaminate the environment. (Land and water) 3. Living things can be harmed or can die 4. Uranium is a non-renewable resource. 5 radioactive waste must be stored safely
What are the advantages of using nuclear energy?
- Makes large amounts of energy using small amounts of fuel.
- Cost cheaper to make electricity than using fossil fuels
- Does not pollute air or greenhouse gasses while in production
- There are few accidents because of very high standards
What is nuclear fusion?
Uses energy given off by the sun. In this process, the nuclei fo small atoms combine to form a new, more massive nucleus. This happens under extremely high temperatures and pressure which brings them together.
What are the products (what is made) during nuclear fusion? See p. 252
Helium nucleus, beta particles, energy from hydrogen nuclei
