Answers to radiometric dating lab
How many parent atoms would remain if three half-lives passed?By counting the numbers of parent atoms remaining in a sample relative to the number originally present, it is possible to determine the number of half-lives that have passed since the initial formation of a mineral grain (that is, when it became a "closed system" that prevented parent and daughter atoms from escaping).You might be wondering how it is possible to know the number of parent atoms that were originally in a sample.This number is attained by simply adding the number of parent and daughter atoms currently in the sample (because each daughter atom was once a parent atom).An individual mineral grain may have a long history after it first forms.
Contrast this with relative age dating, which instead is concerned with determining the orders of events in Earth's past. Scholars and naturalists, understandably, have long been interested in knowing the absolute age of the Earth, as well as other important geological events.
If a radiometric date were to be attained from this mineral grain, it would tell us when the mineral first formed, when the sedimentary rock formed (it would, however, tell us the maximum possible age of the sedimentary rock layer).
Further, heating mineral grains to great temperatures can cause them to leak parent and daughter material, resetting their radiometric clocks.
As more half-lives pass, the number of parent atoms remaining approaches zero. This work is licensed under a Creative Commons Attribution-Share Alike 4.0 International License.
Based on this principle, geologists can count the number of parent atoms relative to daughter products in a sample to determine how many half-lives have passed since a mineral grain first formed. An example of how the initial number of radioactive parent atoms (blue diamonds) in two mineral grains (gray hexagons) changes over time (measured in half-lives) relative to the number of daughter products (red squares). The left-most box in the figure above represents an initial state, with parent atoms distributed throughout molten rock (magma).
Further, suppose that the half-life of the parent atom is 2.7 million years. First, we know that: * 2.7 million years = 1.40 million years.