Which allowed scientists to determine that earth was at leat 4.3 billion years old?
magnetic field surrounding zircon
chemical reactivity of zicron ions
the radioactive decay of uranium to lead
the electrical conductivity of uranium ions
The radioactive decay of uranium to lead allowed scientists to determine that Earth was at least 4.3 billion years old. This is because uranium undergoes radioactive decay over time, and by measuring the ratio of uranium to lead in rocks or minerals such as zircon, scientists can calculate the age of the sample.
The method that allowed scientists to determine that Earth is at least 4.3 billion years old is the radioactive decay of uranium to lead. Here's how they arrived at this conclusion:
1. Radioactive Decay: Uranium is a naturally occurring radioactive element. It undergoes a process called radioactive decay, where its atomic nucleus spontaneously breaks down over time and transforms into a different element. One of the decay products of uranium is lead.
2. Zircon Minerals: Zircon is a common mineral found in Earth's crust. It contains small amounts of uranium and is useful in dating rocks because it incorporates uranium atoms into its crystal structure during formation.
3. Half-Life: Uranium-238, the most abundant isotope of uranium, has a known and constant rate of decay. The time it takes for half of a given amount of uranium-238 to decay into lead-206 is called its half-life, which is approximately 4.5 billion years.
4. Zircon Dating: By analyzing the ratio of uranium to lead in zircon minerals using specialized instruments, scientists can determine the age of the zircon and, by extension, the approximate age of the rock in which the zircon is found. Since uranium-238 has a known half-life, they can calculate how long it took for the uranium to decay into lead and thus determine the age of the zircon sample.
5. Evidence from Zircons: Scientists have found zircons in various rock formations around the world that date back to approximately 4.3 billion years. These zircons contain traces of lead that were formed through the radioactive decay of uranium. By measuring the uranium and lead isotopes in these zircons, researchers can establish an estimate for the age of the Earth.
So, the measurement of uranium-lead isotopes within zircon minerals has allowed scientists to determine that Earth is at least 4.3 billion years old.