Cuesta College, San Luis Obispo, CA
Students have a weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.
The following questions were asked on reading textbook chapters and previewing presentations on radioactive decay modes.
Selected/edited responses are given below.
Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.
"Whether it's stable or unstable, a nucleus always contains a set number of positively-charged protons and neutrally-charged neutrons. Neutrons and protons can be turned into each other to bring stability."
"Radiation is produced from an unstable isotope trying to become stable. If an isotope has too many protons or neutrons to be stable, it has multiple ways to compensate and become stable, all of which produce a different form of radiation."
"Neutrons help keep protons in the nucleus together. I also understood a little about decays."
"The key to stability for all atomic nuclei is being able to keep the protons in the nucleus together. A nucleus with more than 83 protons will always be unstable."
"Having a similar ratio of neutrons to protons makes the nucleus stable. Having more than 83 protons makes the element unstable. There is a force that sticks the protons and neutrons together in the nucleus if the number of protons and neutrons are about the same."
"A strong force holds a nucleus together. When the ratio of protons and neutrons is too uneven, the forces in the nucleus are unstable and fission or decay will occur to balance it. Radioactive decay involves emissions from the nuclei. It can change protons into neutrons and vice versa."
"I think I understand the basic concepts of the nucleus wanting to be more stable. If there are too many protons, they and some neutrons can be ejected to get equal to or below 83 protons. If there are too many protons to neutrons, then electrons can be eaten by the protons to turn them into neutrons. If there are too many neutrons to protons, then electrons can be spit out of neutrons, resulting in more protons."
"I understand the chemistry side of the concepts."
Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.
"It's a bit confusing thinking about a half-life of a radioactive isotope. For example, if you have 10 grams of a radioactive isotope and it has a half-life of 10 years, why does it take 10 years for that radiation to be emitted and for half of the isotopes to become stable? Why do the individual isotopes release their radiation at different times?"
"Stability versus instability."
"Can you please talk a little bit more on how to stabilize an unstable atom?"
"Working with the different radioactive decays."
"While the rules are presented clearly, I still find it hard to determine what type of decay unstable nuclei will undergo."
"Not confident on which process turns protons to neutrons, and vice versa."
"What types of decay lose protons versus gaining them."
"I'm confused on the electron capture process. An electron is eaten, but why are protons decreased and neutrons increased?"
"Gamma decay is confusing since it is different from the other decays."
"The decay processes were a lot to remember. Maybe more explanations on electron capture with the processes would be helpful in lecture."
"Nothing, I love this chapter."
Explain what a "nucleon number" is, and/or describe how to calculate it for a nucleus.
"The total number of protons and neutrons in an atomic nucleus."
"The nucleon number is essentially the mass number of an atom. It is calculated by adding the number of protons and neutrons together. Electrons are not involved because their mass is negligible and therefor not required."
"Z + N = A."
Identify the processes that increase, decrease, or do not change the number of protons in the nucleus.
(Only correct responses shown.)
α decay: decrease. [78%]
β– decay: increase. [63%]
β+ decay: decrease. [50%]
electron capture: decrease. [25%]
γ decay: does not change. [69%]
Identify the processes that increase, decrease, or do not change the number of neutrons in the nucleus.
(Only correct responses shown.)
α decay: decrease. [65%]
β– decay: decrease. [59%]
β+ decay: increase. [59%]
electron capture: increase. [28%]
γ decay: does not change. [69%]
Identify the processes that change a proton to a neutron, or change a neutron to a proton in the nucleus.
(Only correct responses shown.)
α decay: no p/n conversion. [50%]
β– decay: n → p. [66%]
β+ decay: p → n. [63%]
electron capture: p → n. [22%]
γ decay: no p/n conversion. [59%]
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"This is so fun because we are learning the same thing in chemistry right now! Just before doing this homework, I learned what alpha, beta and gamma rays are that are emitted from the nucleus of an atom. Whoa!"
"Not gonna lie, this section made my brain hurt..."
"I would like to see more real life examples of how decay is applied."
"I liked the information about smoke alarms! Very important/relevant to me!"
"The concept of electron capture confused me a little bit, mostly because I don't recall learning about it in chemistry." (Chemistry teachers seem to not want to talk about electron capture, for some reason.)
"YOU MUST MAKE QUIZ 6 REALLY EASY OR RISK DOOMING US ALL!" (Physics 205B: Endgame.)
"Excited for our midterm!"
No comments:
Post a Comment