Radioactive Definition and 391 Threads

Homework Statement A ^{238}_{92} U nucleus can catch a neutron with small kinetical energy. Then we'll get a ^{239}_{92} U nucleus. This nucleus has too many neutrons compared to the number of protons to be stable. How can the nucleus achieve a better balance between neutrons and protons...

I read a recent article (pc magazine) that said the Earth is currently generating 44 terawatts of heat with 23 terawatts comign from radioactive decay (8 from uranium, 8 from thorium, and 4 from potassium). Given this, and that the Earth is 4.5 billion years old...how many more terawatts were...

I am wondering what any experts think about these Wikipedia explanations of radioactive decay. (Wiki asks for help improving this article, so somebody must recognize some issues.) Thanks. under "EXPLANATION": Huh?? Does this mean anything?? What does "activation energy"...

Could you make a solar sail that derives it's energy from the decay of a radioactive element such as plutonium, uranium, or palonium? I understand that such elements radiate in all directions but if you had a 1 kg sphere of it attached to a boon which was attached to a reflective sail (e.g...

Does time dilation effect radioactive decay? For example, if I speed a radioactive atom up to near light speeds, will its decay slow? If so, could this be used to study atoms with a very short decay time?

Radioactive isotopes or radioisotopes are they only found in nuclear reactors? Or can they be found in the natural world as well?

I saw references on the web to periodicities in radioactive decay that are hypothesized to correspond to the varying levels of neutrinos emanating from the sun. How do neutrinos affect radioactive decay?

Ok, so all elements undergo radioactive decay. But why? I have been snooping around and what i find is that radioactive decay occurs because of instability of the atom nucleus in quantity, proton-neutron ratio and energy content; therefore we have alpha, beta and gamma decay consecutively...

Homework Statement I have some data for "Activity(Bq * 10^4)" and "time". I have already found the half life and everything but I can't seem to see any sources of error in the data Homework Equations I need sources of error. The Attempt at a Solution I said, the half life matches the...

I apologize for the simplicity of this question in relation to the others on this site. But I've been curious, and haven't been able to find an answer. In Radioactive Dating, how do scientists know how much of a certain isotope (ie. Carbon-14, Potassium-40) was there to start with in an...

What does "Activity" mean in terms of radioactive decay? I came across this term "activity" in text regarding radioactive decay and half lives. It is defined as "number of nuclei in a sample that decay within a given time." That definition if fine but then when presented in a graph life...

Hello, Quick question: Will radioactive particles give interference pattern if there is no measuring device?

I've seen a lot of talk recently about radiation and radioactive materials. I was wondering what the major issues with storing these materials are and what materials are posing the most risks. Which ones are the biggest hazards? Products that are gases instead of solids/liquids? Ones that...

A sample of an ancient rock contains one atom of lead for every atom of uranium. the uranium in the rock has a half - life of 4500 million years. It decays to form lead which is not radioactive. Explain why the age of the rock is 4500 million years. I assumed that 1 x 4500 million years = 0.5...

These are just a few practice questions I found difficult, I would appreciate it if you could provide step-by-step explanation on how to solve the following problems. I checked all my answers in the textbook and got the following wrong, but cannot work out how to arrive at the right answer...

So... I know that decay occurs when the nucleus of an atom has an unstable proton-neutron configuration. My question is, at the instant that decay occurs, what triggers it? Is it quantum mechanical in nature? If so, why are half lives so consistent?

I read about neutralizing radioactivity in soil by using paramagnetic clays or ashes because it may chelate the radioactive particles and bind them tightly so they cannot be absorbed by the plant. How true is that?

Homework Statement The technique known as potassium-argon dating is used to date old lava flows. The potassium isotope 40K has a 1.28 billion year half-life and is naturally present as very low levels. 40K decays by beta emission into 40Ar. Argon is a gas, and there is no argon in flowing...

A radioactive nucleus of mass 235 units traveling at 400 km/s disintegrates into a nucleus of mass 95 units and a nucleus of 140 units. If the nucleus of mass 95 units travels backwards at 200 km/s what is the velocity of the nucleus of mass 140 units? Momentum before = Momentum After...

Greetings, I have seen science fiction movies where a Geiger counter is used to tell if someone has radiation poisoning. Does being exposed to radiation from a radioactive substance make a person radioactive? Thanks

Is this true? How do you refute it? http://www.scientificamerican.com/article.cfm?id=coal-ash-is-more-radioactive-than-nuclear-waste

For the basic model for exponential decay, there is a decay constant, which is related to the half-life. The decay constant multiplied by the number of particles should give the decay rate per second (activity). However, the model I want is for small periods of time. For a small enough period of...

Hi, With the possible meltdown in Japan, I've been thinking why a meltdown is that dangerous. I'm not sure whatever the kind of radiation is that exists behind a radiation but if it is: -Alfa-decay: I think it's quite easy if the nuclear trash is put in a box with a thick border, I expect the...

the assignment is written as follows: A parcel is attracting nervous attention at australian post. the parcel is radioactive and inspectors are trying to identify the material. Suppose they make the following measurements. There are 50 grams of the material and it's decaying at a rate of 0.25...

Homework Statement I hope that I'm posting it in the right section... I did an experiment in class using a Geiger-Muller counter with the objective to find the amount of counts (how many photons hit the detector) due to natural radioactivity around my work station. I recorded 45 values of...

Homework Statement It is found that when a 6.3 x 10–5 g sample of radium-226 is placed in a vacuum and exposed to a screen of area 1.0 mm2 placed 1.5 m away from the sample, an average of 46 α-particles hit the screen in 10.0 minutes. Calculate the total number of decays per gram of...

Homework Statement The sample is placed 0.12 m beneath a Geiger counter. The counter registers 2 counts per second. What is the activity of the sample?Homework Equations The Attempt at a Solution Just a guess. I am making up formulas here so please tell me if they're not even true. (2...

Homework Statement If 20% of a radioactive substance disappears in 70 days, what is its half-life? Homework Equations y = C*e^(k*t) where t is time in days k is the constant of proportionality? y is the current amount of substance The Attempt at a Solution 20% disappears, so...

Hello! I'm new to the forum so please don't mind any mishaps. I am very interested in the unstable radioactive elemts. I read that the thing that makes elements radioactive is ther different amounts of neutrons. Does this mean that all the radioactiive elements are radioactive just because...

i am wondering if we know decays like Samarium-neodymium and Rubidium-strontium with half-lives of 106 and 49 billion years, why scientists consider the age of Earth based on Uranium-lead dating with half-life of 4.47 billion years? i mean if there wasn't Earth 100 billion years ago, where these...

hello! i'm planning to build such a generator, but i have some questions: 1. what dimensions and materials are needed to shield one typical geiger-muller tube from the background radiation? 2. even with the complete protection, is it possible that the counter tube will trigger without...

Homework Statement I am looking for some guidance on how to tackle the following problem. Maybe I am a little confused as it is rather wordy. It is known that an isotope, X, spontaneously decays by positron emission into another isotope, Y, with a half life of 100 minutes. The isotope X...

Homework Statement A radioactive nucleus can decay by two different processes. The half life for the first processes is t_{1} and that for the second is t_{2}. Show that the effective half life t of the nucleus is given by \frac{1}{t}=\frac{1}{t_{1}}+\frac{1}{t_{2}}Homework Equations...

Homework Statement You have two samples that exhibit radioactive decay. The first gives you initially a 1000/s decay rate and after one hour a 500/s decay rate. The second gives you initially a 500/s decay rate and after one hour a 250/s decay rate. Which sample has a higher probability per...

Homework Statement A sample of pure 99mTc is obtained and has an activity of 5000MBq. What will be the approximate change in mass of this sample after it has all decayed to 99Tc (assume no further decay from this state). (Avogadro's number = 6.023x1023 per mole; Half life of 99mTc = 6Hrs...

I can't seem to get this started in the right direction. Any help is appreciated. As part of a treatment program, a patient ingests a radioactive pharmaceutical containing P32,15, which emits beta rays with an of 1.50. The half-life of is 14.28 , and the initial activity of the medication...

I have been trying for quite some while but I can't seem to get this problem off the ground.1)Suppose that you hydrolyze 4.644 grams of a protein to form a mixture of different amino acids. To this is added a 2.80 mg sample of 14C-labeled threonine (one of the amino acids present).The activity...

Homework Statement c) In 420 days, the activity of a sample of polonium, Po, fell to one-eighth of its initial value. i) Calculate the half-life of polonium. Homework Equations The Attempt at a Solution if the activity fell by 1/8 then it went through 4 half liefs (1/2*4=1/8) so...

Homework Statement complete the following decay equations by inserting the missing particle or nuclide information. Identify each type of decay. see attached screenshot please. Homework Equations The Attempt at a Solution I've done all of the decays but we have to label them and...

http://www.vancouversun.com/technology/Critics+attack+plan+ship+tonnes+radioactive+waste+across+Great+Lakes/3591392/story.html Hey, I apologize if this is posted elsewhere - I tried a search and nothing came up. I've been following this story about Canada's decision to ship radioactive...

Homework Statement Complete the following decay equations by inserting the missing particle or nuclide information. Identify each type of decay. i) 90?Sr = ?39Y + ? + ? ii) 22?Na = ??Ne + β+ + ? + energy iii)24294Pu = ??? + alpha + ? iv) 235?U =...

How can we prove that the mean life time of a radioactive decay is reciprocal to the decay constant?

You have 100 grams of radioactive material, how do i know the half life and the time i have 100 grams of material X. you do not know the half-life you do not know the time it started to decay what is its half-life/starting time? is this equation even solvable? if so, how?

http://www.symmetrymagazine.org/breaking/2010/08/23/the-strange-case-of-solar-flares-and-radioactive-elements/" I just read this article. It suggests that solar activity has been shown to affect the rate of nuclear decay in the lab and that a particle may be responsible. Is this new information...

How are Madame Curie's notebooks still radioactively dangerous when Hiroshima is not?

We are taught that the three basic types of radioactive particles are alpha, beta, and gamma. I know there are other particles, but for now I'm just focusing on these. Alpha particles don't penetrate skin, beta particles do and can cause burns, and gamma rays are very powerful. But my chem...

Radiomagnetism or radioactive magnetism. Has any research been done on this phenomenon as a source of propulsion. Are we thinking too small? Can the various levels of radioactivity affect magnetic propulsion by increasing its magnitude. What would be required to observe this on a large scale...

Homework Statement Nitrogen in the upper atmostphere is convereted by radiation to carbon 14 the half-life of carbon, \tau = 5730 years carbon 14 makes up a known proportion of living plants and animals, after they die, the proportion of carbon 14 decays. - History records that an eruption...

Homework Statement 2.71g sample of radioactive KCl is decaying at a constant rate of 400Bq into the isotope 40K. which constitutes 1.17% of normal K. calculate the half life of this nuclide. Homework Equations we have dn/dt = n * lamda and t-1/2 = 0.693/lamda. The Attempt at a...

It takes an infinite time for complete decay of a radioactive element. but on the same time we calculate the half life of radioactive material i-e T-1/2 = ln 2 / lamda. is that means that if we double the half life time we could reach the total life time of radioactive decay so on contrary we...