Uranium-238 decays by alpha emission with a half-life of (4.4683 ± 0.0048) × 109 years (Jaffey et al., 1971) to 234Th, which in turn decays (half-life = 24.1 days) by beta emission to 234Pa, which decays (half-life = 6.7 h) by beta emission to 234U, which decays (half-life = 245 620 ± 250 years; Cheng et al., 2012) by
How is the half-life of an element determined?
The half-life is then determined from the fundamental definition of activity as the product of the radionuclide decay constant, λ, and the number of radioactive atoms present, N. One solves for λ and gets the half-life from the relationship λ = ln2/T1/2.
How is the half-life of a radioactive isotope determined?
One important measure of the rate at which a radioactive substance decays is called half-life, or t1/2. Half-life is the amount of time needed for one half of a given quantity of a substance to decay. By measuring the decay of a sample of barium-137, you will be able to calculate its half-life.
One quick way to do this would be to figure out how many half-lives we have in the time given. 6 days/2 days = 3 half lives 100/2 = 50 (1 half life) 50/2 = 25 (2 half lives) 25/2 = 12.5 (3 half lives) So 12.5g of the isotope would remain after 6 days.
How is U 238 used to determine the age of a rock?
Uranium-238, whose half-life is 4.5 billion years, transmutes into lead-206, a stable end-product. Boltwood explained that by studying a rock containing uranium-238, one can determine the age of the rock by measuring the remaining amount of uranium-238 and the relative amount of lead-206.
Does every element have a half-life?
Elements with short half lives exist because each element has stable isotopes, and the decay os isotopes create more isotopes as well. Certain elements have extremely short half-lives, such that they decay at a very rapid pace. Isotopes have the same number of electrons, and therefore have the same chemical properties.
Whats the half-life of uranium 235?
about 700 million years The half-life of uranium-238 is about 4.5 billion years, uranium-235 about 700 million years, and uranium-234 about 25 thousand years.
What is the easiest way to find half-life?
1:233:52Half Life Calculations Part 1 (easy way) - YouTubeYouTube
Why is U 238 used to date the Earth instead of I 131?
Uranium 238 has a half life of 4.5 billion years. Uranium can be used to date the age of the earth. If 50% of pure uranium is left in a sample the sample is assumed to be 4.5 billion years old. So no fossils can be dated directly using U 238.
What is the most unstable element?
Francium is one of the most unstable of the naturally occurring elements: its longest-lived isotope, francium-223, has a half-life of only 22 minutes. A heavy element with a single valence electron, it has the highest equivalent weight of any element.
Why is U-238 more stable than U-235?
U-238 is the most abundant uranium followed by U-U- 235 and 234. The difference between the three isotopes is the number of neutrons present in the nucleus. U-238 has 4 more neutrons than U-234 and three more neutrons than U-235. U-238 is more stable thus being more abundant naturally.
What is considered a short half-life?
Half-lives of drugs are therefore generalizations and not exact. Shorter half-life drugs tend to take action quickly, and their effects may wear off rapidly as well. A long half-life drug, on the other hand, may stay in the body for longer than a person wants it to as the effects can be prolonged.
Which hormone has the shortest half-life?
Which of the following hormones has the shortest plasma half-life? The correct answer is E. NE half life is approximately 2 min. Corticosterone half life is 60–90 min renin is 10–15 min; DHEA is 15–38 min; aldosterone is 20 min.