Parts of an Atom
This refers to the amount of protons given in a specific type of atom.
The Atomic Number
Define radioactive decay.
A spontaneous process in which unstable nuclei lose energy by emitting radiation as they release various particles from their nucleus.
Define the term half-life.
The length of time required for half of the radioactive atoms in a sample to decay.
What are the two types of nuclear reactions?
Fission and Fusion
Define the "Strong Force."
attractive force that acts between protons and neutrons in an atomic nucleus
Define Average Atomic mass.
The weighted average of the atomic masses of the element including naturally occurring isotopes of said element.
Describe what happens to an atom when it undergoes alpha decay AND draw the particle.
Hint: be VERY specific
When an atom undergoes alpha decay it will release 2 protons and 2 neutrons. It is also called a Helium atom. It mass will decrease by 4, and its atomic number will decrease by 2.
42He
Can the half-life of a material be altered? Explain your answer.
No.
Half-life is a rate that cannot be changed by any amount of heat, pressure or other outside force. This is the key factor why people are concerned about radioactive waste --> it will be around for a very long time and there is nothing we can do to change that.
Define the processes of Fission and Fusion.
Fission - The splitting of an atomic nucleus to release energy.
Fusion - Creation of energy by joining the nuclei of two hydrogen atoms to form helium.
Compare and contrast leptons and hadrons.
Leptons - fundamental particles that cannot be broken down anymore (electrons)
Hadrons - elementary particles that can be broken down into smaller pieces called quarks (protons and neutrons)
Explain why Bohr's Model of the atom was incorrect.
1.) Bohr's model was too simple. Electrons are moving so fast there is no way to accurately describe their position and speed with direction. A more advanced model was needed (probability distribution.)
2.) When observing what type of light/energy was released when electrons fell from their excited states, Bohr's model only worked for Hydrogen because it only had 1 electron.
What determines if an atom is unstable or not, in order to undergo any form of decay?
The ratio of protons to neutrons in the nucleus should be close to a 1:1 ratio in order to be considered stable. When atoms do not have this ratio their nuclei tend to release parts in order to close the gap on that ratio.
An isotope has a half-life of 6 hours. What percentage will be left after 24 hours?
**You have 10 seconds**
6.25%
What makes nuclear reactions different from chemical reactions?
Nuclear reactions do not involve electrons like chemical reactions. Instead, it only involves the nucleus (protons and neutrons) and the energy that binds it (the strong force.)
Describe the penetrating ability of each type of radioactive decay.
alpa - weakest, blocked by paper and clothes
beta - middle, blocked by thin sheet of aluminum
gamma - strongest, blocked by meters of lead or concrete
Find the following information for Pm-147:
- element name & symbol
- Z & A
- amount of ALL subatomic particles
**You have 10 seconds**
Promethium - Pm
61 & 147
61p, 61e, 86n
Explain what happens to an atom when it undergoes beta decay AND draw the particle.
Hint: be VERY specific
A neutron will spit out an electron (the beta particle) and turn into a proton. This will increase the atomic number by one and mass will not change.
0-1e
Calculate the half-life of the radioactive isotope in a source if its mass decreases from 24g to 6g over a period of 60 days.
**You have 10 seconds**
30 days
Explain what happens during a nuclear fission chain reaction. Be specific and use appropriate vocabulary.
In a nuclear fission chain reaction, a free neutron interacts with the nucleus of an atom and causes that nucleus to split apart into two new, less massive nuclei. The ruptured nucleus in turn releases additional neutrons, which can cause additional nuclei to split, and so on.
Describe the pros and cons to using fission as an alternative energy source as compared to fusion.
Pros - clean energy, easier to control than fusion, cheaper than fusion, gives job stability, economically profitable, very small amounts of fuel go a very long way.
Cons - fuel is radioactive and has long half-lives which means the storage of the material has to be planned and available for a long time.
Give the electron configuration for Manganese.
**You have 10 seconds**
1s22s22p63s23p64s23d5
Explain how gamma radiation and decay occurs and how it it changes an atom.
Draw the particle.
Hint: be VERY specific
00Y
A radioactive source has a half-life of 3 hours. At 8 am it has an activity of 600 Bq. What will it's activity be at 2pm?
**You have 10 seconds**
150 Bq
How is the fission that occurs inside an atomic bomb different from the fission that occurs in a nuclear power plant?
Nuclear fission that occurs inside of bombs is uncontrolled. When a fission reactor is being monitored, they can lower control rods into the reactor to absorb neutrons which slows the reaction.
Chlorine-35 has an actual mass of 34.9689 u and chlorine-37 has a mass of 36.9659 u. In any sample of chlorine atoms, 75.771% will be chlorine-35 and 24.229% will be chlorine 37. Calculate the average atomic mass of chlorine.
Hint: USE CORRECT SIGFIGS!
(34.9686 * .75771) + (36.9659 * .24229) =
5 sigfigs 5 sigfigs
35.45275313 amu
FINAL ANSWER: 35.453 amu