Radiometric dating parent daughter isotopes
Uranium's atomic number is 92, corresponding to its number of protons.
which decay into lead-206 and lead-207 respectively.
This is because when radioactive elements first come into being, they are presumed to consist entirely of a single isotope.
Imagine that you enjoy a certain kind of ice cream flavored with chocolate chips.
For example, certain drugs, including ethyl alcohol, are metabolized by the body at a fixed number of grams per hour (or whatever units are most convenient).
If someone has the equivalent of five drinks in his system, the body takes five times as long to clear the alcohol as it would if he had one drink in his system.
Because your roommate eats half of the chips on any given day, and not a fixed number, the carton must have held 20 chips the day before, 40 the day before that, and 80 the day before that.U-Pb dating is often used to date igneous (volcanic) rocks, which can be hard to do because of the lack of fossils; metamorphic rocks; and very old rocks.All of these are hard to date with the other methods described here.Sure, you can scour the Internet and learn rather quickly that the scientific consensus pins the age of of the planet at about 4.6 billion years.
But Google didn't invent this number; instead, human ingenuity and applied physics have provided it.You also need to know when you can or cannot apply a particular type of device to the task at hand; for example, if you want to know how hot it is on the inside of an active wood stove, you probably understand that putting a household thermometer intended to measure body temperature inside the stove is not going to prove helpful.