We have also obtained a very similar age by measuring Pb isotopes in materials from earth. I should mention that the decay constants basically a value that indicates how fast a certain radioactive isotope will decay for some of these isotope systems were calculated by assuming that the age of the earth is 4. The decay constants for most of these systems have been confirmed in other ways, adding strength to our argument for the age of the earth. Radiometric dating depends on the chemistry and ratios of different elements.
It works like this:. Take, for example, zircon, which is a mineral; its chemical formula is ZiSiO 4 , so there is one zirconium Zi for one silicon Si for four oxygen O. One of the elements that can stand in chemically for zircon is uranium. Uranium eventually decays into lead, and lead does not normally occur in zircon, except as the radioactive decay product of uranium.
Therefore, by measuring the ratio of lead to uranium in a crystal of zircon, you can tell how much uranium there originally was in the crystal, which, combined with knowing the radioactive half-life of uranium, tells you how old the crystal is. Obviously, if the substance you are measuring is contaminated, then all you know is the age since contamination, or worse, you don't know anything, because the contamination might be in the opposite direction - suppose, for example, you're looking at radio carbon carbon 14, which is produced in the atmosphere by cosmic rays, and which decays into nitrogen.
Since you are exposed to the atmosphere and contain carbon, if you get oils from your skin onto an archeological artifact, then attempting to date it using radio carbon will fail because you are measuring the age of the oils on your skin, not the age of the artifact. This is why crystals are good for radiometric dating: The oldest crystals on Earth that were formed on Earth are zircon crystals, and are approximately 4.
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Asteroids in the solar system have been clocked at 4. We assume that the Earth is probably as old as the asteroids, because we believe the solar system to have formed from a collapsing nebula, and that the Earth, being geologically active, has simply destroyed any older zircon crystals that would be its true age, but we can't really be certain. The building blocks that the Earth is made of, the asteroids are 4. Based on astronomical models of how stars work, we also believe the Sun to be about 4.
Radiometric dating is a widely accepted technique that measures the rate of decay of naturally occurring elements that have been incorporated into rocks and fossils. Every element is defined by the particular number of protons, neutrons, and electrons that make up it's atoms. Sometimes, the number of neutrons within the atom is off.
These atoms, with an odd number of neutrons, are called isotopes. Because they do not have the ideal number of neutrons, the isotopes are unstable and over time they will convert into more stable atoms. Scientists can measure the ratio of the parent isotopes compared to the converted isotopes.
The rate of isotope decay is very consistent, and is not effected by environmental changes like heat, temperature, and pressure. This makes radiometric dating quite reliable. Try refreshing the page, or contact customer support. Register to view this lesson Are you a student or a teacher? I am a student I am a teacher. What teachers are saying about Study.
Conditions of Fossil Preservation: Are you still watching? Your next lesson will play in 10 seconds. Add to Add to Add to. Want to watch this again later? What is Radioactive Dating? Principles of Radiometric Dating. Relative Dating with Fossils: Index Fossils as Indicators of Time. Methods of Geological Dating: Numerical and Relative Dating.
Radiometric dating - Wikipedia
What is Relative Dating? What is the Age of the Solar System? Absolute Time in Geology. What is Carbon Dating?
Radiometric Dating: Methods, Uses & the Significance of Half-Life
Methods for Determining Past Climates. Introduction to Physical Geology: Intro to Natural Sciences. Middle School Earth Science: Weather and Climate Science: UExcel Weather and Climate: Guns, Germs, and Steel Study Guide. Holt McDougal Introduction to Geography: Radiometric dating is used to estimate the age of rocks and other objects based on the fixed decay rate of radioactive isotopes. Radiometric Dating The aging process in human beings is easy to see.
Radioactive Decay The methods work because radioactive elements are unstable, and they are always trying to move to a more stable state. Half-Life So, what exactly is this thing called a half-life?
Uranium-Lead Dating There are different methods of radiometric dating that will vary due to the type of material that is being dated. Potassium-Argon and Rubidium-Strontium Dating Uranium is not the only isotope that can be used to date rocks; we do see additional methods of radiometric dating based on the decay of different isotopes. Radiocarbon Dating So, we see there are a number of different methods for dating rocks and other non-living things, but what if our sample is organic in nature? Try it risk-free No obligation, cancel anytime.
Want to learn more? Select a subject to preview related courses: Lesson Summary Let's review. Learning Outcomes As a result of watching this video, you might be able to: Compare radiometric dating, radioactive decay and half-life Understand that uranium-lead dating is one of the most reliable radiometric dating methods Relate the processes of potassium-argon and rubidium-strontium dating Determine how radiocarbon dating works and recognize why it is important. Unlock Your Education See for yourself why 30 million people use Study. Become a Member Already a member? Earning College Credit Did you know… We have over college courses that prepare you to earn credit by exam that is accepted by over 1, colleges and universities.
To learn more, visit our Earning Credit Page Transferring credit to the school of your choice Not sure what college you want to attend yet? Browse Articles By Category Browse an area of study or degree level. You are viewing lesson Lesson 6 in chapter 2 of the course:. Earth Science 24 chapters lessons 16 flashcard sets. Earth's Spheres and Internal Rock Deformation and Mountain Water Balance on Earth.
Studying for Earth Science Different methods of radiometric dating vary in the timescale over which they are accurate and the materials to which they can be applied. All ordinary matter is made up of combinations of chemical elements , each with its own atomic number , indicating the number of protons in the atomic nucleus. Additionally, elements may exist in different isotopes , with each isotope of an element differing in the number of neutrons in the nucleus. A particular isotope of a particular element is called a nuclide.
Some nuclides are inherently unstable.
That is, at some point in time, an atom of such a nuclide will undergo radioactive decay and spontaneously transform into a different nuclide. This transformation may be accomplished in a number of different ways, including alpha decay emission of alpha particles and beta decay electron emission, positron emission, or electron capture. Another possibility is spontaneous fission into two or more nuclides.
While the moment in time at which a particular nucleus decays is unpredictable, a collection of atoms of a radioactive nuclide decays exponentially at a rate described by a parameter known as the half-life , usually given in units of years when discussing dating techniques.
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