Week 4
Universe
Nuclear Reactions
CLICK links below to hear a Science Course Mentor provide an overview to this section, “Nuclear Reactions”- two recordings available (below): http://wgu.connectpro.acrobat.com/p65428391/ http://wgu.connectpro.acrobat.com/p56013020/
Use Chapter 10, Conceptual Integrated Science to address the following items in your notes:
1. Describe the general structure of an atom. Atoms are made up of electrons neutrons and protons. The neutrons and protons lie in heart of the atom, in the Nucleus.
2. What makes an atom radioactive? When a Atom has a stable nuclei it has the right balance of neutrons to protons and the right amount of energy to remain unchanged for a long period of time. Other atoms that do not have the right mix of protons or neutrons or have the wrong amount of energy are said to be unstable Atoms with unstable nuclei are said to be radioactive.
3. Explain the difference between an alpha particle, a beta particle, and a gamma ray. ALPHA RAYS carry a positive charge, BETA RAYS carry a negative charge and GAMMA RAYS carry no charge. ALPHA PARTICLES are the combination of two protons and two Neutrons. Alpha particles are easy to shield because of their big size and their double positive charge. They can cause significant damage to the surface of materials because of their kinetic energy. BETA PARTICLES is a electron ejected from a nucleus. Once ejected it is an indistinguishable from a electron in a cathode ray or in a electrical circuit. The difference is that a beta particle originates inside the nucleus from a neutron. A beta particle is faster than a alpha particle and caries a single negative charge. Beta particles are not as easy o stop as alpha particles and they are not as easy to stop they can penetrate paper and clothing. Beta particles can penetrate the skin and kill living cells but they cannot penetrate dense materials such as aluminum once they are stopped they become part of the material. GAMMA RAYS are the high frequency electromagnetic radiation emitted by radioactive elements. A gamm ray is pure energy. They are able to penetrate through most materials but cannot penetrate through very dense material like lead.
4. List sources of radiation. Nature, TV, cell phone, computer monitor, medical testing, coal and nuclear power industries.
5. What is the difference between a rad (radiation absorbed dose) and a rem (roentgen equivalent mass)? A RAD is the commonly used unit of measure to measure radiation a REM is the way we measure radiation to see how harmful ti is. If we have two arrows on with a pointed tip and one with a suction cup and shoot them at the apple we would measure the REM to see the difference in the damage.
6. Explain the strong nuclear force and the electric force in an atom. Two protons near each other experience both a attractive strong nuclear force and a repulsive electric force. At this tiny separation distance the strong nuclear force overcomes the electric force and resulting in their remaining together. When the two protons are relatively far apart from each other the electric force is more significant the protons repel each other.
7. Why must the strong nuclear force be present in the nucleus of an atom? If there wasn’t anything holding the atom together then all there would be is Hydrogen. The strong Nuclear force keeps the atom stable.
8. How does the size of an atom affect the strength of the strong nuclear force and the electric force?
9. What happens during nuclear fission? If a uranium nucleolus stretches into a elongated shape the electrical forces may push it into even a more elongated shape when the elongation passes a certain point electrical forces overwhelm strong nuclear forces and the Nucleus splits causing NUCLEAR FISSION.
10. Why is a critical mass of radioactive material necessary for a large explosion? Because of the chain reaction effect when Nuclear fission happens. When nuclear fission