Radiometric dating assignment answers
Specifically, by dividing the number of parent isotopes currently left in the sample ( Is this radioactive decay formula intimidating?If so, try not to worry: This science project will only use its graphical representation, known as the decay curve .So, how do geologists use radioactive decay as clocks to measure the age of a sample?Using a technique called radiometric dating, geologists take a sample of the material and measure the number of parent and daughter isotopes present in the sample.As an example, the potassium-40 isotope (which contains 19 protons, 40 nucleons, and is represented by the atomic symbol K) will change into the argon-40 isotope (which contains 18 protons, 40 nucleons, and is represented by the symbol Ar).When this happens, potassium-40, which is emitting particles in its conversion to a more stable form, is called the parent isotope.Geologists (along with paleontologists, archeologists, and anthropologists) actually turn to the elements for answers to their geological time questions. The nucleus itself is made of protons and neutrons, collectively called nucleons.
In this science project you will see for yourself by modeling radioisotope dating with a few rolls of the dice. Retrieved January 12, 2018 from https:// As humans, it seems easy for us to keep track of time lapses, as long as they range from a couple of seconds to a number of years.
You can probably see now that as the sample ages, fewer and fewer parent isotopes will be present in the rock, so the rock will be less and less radioactive. The radioactivity levels are indicated by wiggly arrows; green dots represent parent isotopes (here, K-40) and yellow dots represent daughter isotopes present in the rock at the indicated time after the formation of the rock.
Figure 3 shows a graphical representation of this example. Snapshots of the rock are taken after multiples of 1.25 billion years (the half-life time of the parent isotope K-40).
To take it a step further, once only 1/4 of the original amount of K-40 isotopes are left (half of the half left over after 1.25 billion years), geologists can say that 2.5 billion years (double the half-life time) have gone by.
Now, can you predict how much time has gone by if only 1/8 is left?