Download Radioactivity Mid-Unit Review Questions

https://goo.gl/06HE3Y
Ethan Michalski Mid-Unit Review Answers are in red!
Joey Miller - Answers are in green! (Go MSU!)
Carim Calkins - Answers in Blue as I edited things
Radioactivity Mid-Unit Review Questions
Use your radioactive decay series chart and your periodic table to answer these review questions.
1. If I find some hydrogen that has one proton no neutrons and one electron is that the hydrogen
on the periodic table or not? Explain your answer. Yes it is because the mass # would be 1 (due
to the proton) and that is the atomic mass that is closest to the number on the periodic table.
There is one electron to balance the charge on the proton.
2. A thorium-234 atom near the hydrogen from question #1 undergoes beta decay and the
electron that flies off is caught by the hydrogen, what do we now call that hydrogen atom due to
having the extra electron? A hydrogen ion. (Negative hydrogen ion because of -1 charge)
3. I have a carbon-14 atom that undergoes beta decay. Since carbon-14 has _6____ protons
__8___ neutrons and __6____ electrons when it starts, how many does it now have after the
beta decay? It has 7 protons 7 neutrons and 6 electrons. The one “missing” neutron turned into
a proton + electron + energy when it went through beta decay. The high energy electron comes
flying out of the atom’s nucleus, then flies off the atom. The atom will quickly find another
electron to make the atom be neutral with 7 protons and 7 electrons. I will accept the answer of
7, 7, and 7 for protons, neutrons, and electrons.
WATCH THIS VIDEO! (C-14 formation is explained:
http://science.howstuffworks.com/environmental/earth/geology/carbon-141.htm )
Otzi the iceman - http://news.nationalgeographic.com/news/2013/10/131016-otzi-ice-manmummy-five-facts/
4. Is the carbon-14 from the previous question carbon right off the periodic table, or is it an isotope
that is different from the isotope of carbon that is shown on the periodic table? Explain your
answer. This is an isotope of carbon 12, which is the most frequent isotope of carbon so it’s the
one on the periodic table. I know this isn’t the carbon on the periodic table because carbon-14
would have still 6 p+ but would have 8 no instead of the 6 no that carbon-12 has (having 6
neutrons because 12-6=6). That would make the mass number 14 rather than 12 like on the
periodic table, so it’s not the isotope that is on the table (having 8 neutrons because 14-6=8).
5. I have some radon that undergoes its normal decay as shown on the radioactive decay series.
When it decays, what happens to its atomic number, mass number, and number of electrons?
Atomic # goes down by 2 (because the chart tells us it’s losing an alpha particle), the mass #
goes down by 4 (the mass of the 2 protons and 2 neutrons in an alpha particle) and the
electrons go down by 2, to keep it a neutral charge. (It turns into Polonium-218)
6. The alpha decay particle from radon gas in your basement enters your lungs. Why is this
dangerous, and what can it do to your lungs when it's there? Explain this in terms of
radioactivity and ionizing radiation. This particle is dangerous because it can go through your
cells, and break and change your DNA or other important molecules, killing cells and changing
others causing the possibility of cancers and other defects.
7. List the names of the types of ionizing radiation we have studied so far, describe what they are,
and explain how they do their damage to living things. We have studied alpha beta particles,
and gamma rays. They damage living things by changing the DNA in your body, killing cells and
causing new most-likely cancerous cells.
A. Alpha decay: it is an He nucleus that leaves the radioactive atom. This ɑ decay⇒ loss of
2p+ & 2n0.
B. Beta decay: β decay⇒ loss of 1e- that comes flying out of the nucleus with great energy
and disrupts other atoms or molecules in the area by changing their bonds or moving into
their electron cloud and making them an ion when they shouldn’t be one.
C. Gamma decay: High energy, short wavelength gamma rays come from some unstable
radioactive nuclei and they can interact with other atoms to strip off electrons from the
electron cloud.
8. What is the immediate daughter product of the decay of U-234? What’s the difference between
the U-234 and its daughter product? Thorium 230. Due to alpha decay, it lost 2 protons, and 2
neutrons, making it a different element and also dropping mass number by 4, and dropping the
atomic number by 2.
9. An element undergoes an alpha decay and then the daughter products go through a series of 2
beta decays. What happens to its atomic number? Mass number? Atomic Number goes down
by 2 and mass number goes down by 4 for alpha decay (2p+ & 2n0 ), then a neutron changes
into a proton during each of the beta decays, since the atomic number is based on the number
of protons, it goes down and up by 2, meaning it’s the same at the end as it was at the
beginning. Also, since there are 2 neutrons lost in the release of the alpha particle, the atomic
mass goes down by 2. The atomic mass in our calculations would not be changed during beta
decay, since each neutron becomes a proton and they have the same mass (ignore the
electrons in middle school). End result: its mass number goes down by 4, and the atomic
number doesn’t change.
10. List the 3 parent elements on the uranium decay series that can undergo the change(s) you
wrote about in the previous question. Uranium-238, Polonium-218, and Polonium-214
11. If an element and its daughter products undergo a beta decay, then an alpha decay, then emit
some gamma rays, and finally undergo another beta decay, how does the nucleus of the final
decay product compare to the original parent element? Beta = 1 less neutron, 1 more proton.
Alpha = 2 less protons, 2 less neutrons. Gamma = no change. Another beta = 1 less neutron
and 1 more proton. End result: same protons but 4 less neutrons. Example is Bismuth 214, to
Bismuth 210 (except the gamma rays are released from the wrong radioisotope in the series I
gave you, just like in real life).
12. In the previous question, list all of the items that come out of the nucleus of the atom as it
goes through the decays. 2 neutrons and 2 protons are lost when the alpha particle leaves the
nucleus. Then a proton is gained as a neutron is changed during each of the two beta decays,
but they don’t leave the nucleus. However, 2 high energy electrons come flying out of the
nucleus, one for each beta decay. The gamma radiation doesn’t affect the nucleus as gamma
rays only strip electrons from atoms ionizing them. Ultimately, that means that you lose 2
neutrons, 2 protons, and 2 electrons that all come out from the nucleus.