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Chapter 12 Science

Chapter 12 Vocabulary

Uniformitarianism the concept that processes that have shaped earth in the past are about the same as those operating today.
radioactivity the spontainous decay of certain unstable atomic nuclei.
half-life the time required for onr half of the atoms oif a radioactive substance to decay.
radiometric dating the procedure of calculating the absoulute ages (in years) of rocks and minerals that contain radioactive isotopes.
The type of rock in which most fossils are found that can also be used as a clue to the enviroment that existed when it began to form and in which the organisms lived? Sedimentary
From what kinds of rock in scietists obtain an absoulute age? Igneous rocks can be dated whether they cause matamorphism, cross cut earlier rocks, or were covered up with sediments.
What are three examples that fit uniforitarism? volcanic eruptions, erosions, and radioactive decay
How does stable carbon 12 differ from unstable carbon 14? Carbon 12 has six protons and neutrons while carbon 14 has six protons and eight neutrons. Carbon 14 has an unstable nucleus that radiates energy and paticles.
What happens in radioactive decay? Unstable elements decay to a different element.
How do you find absolute age? Calculate how much daughter element (or parent element) of a radioactive element remains within rock to determine how many half-lives have occurred since decay rate is constant.
What are 3 types of radioactive decay? beta decay, alpha decay, and electron capture
What happens in electron capture radioactive decay? The nucleus captures an electron to turn a proton into a neutron.
What happens in beta decay (radioactive decay)? A neutron is turned into a proton and an electron.
What happens in alpha decay? A helium nucleus (alpha particle) is emitted because there are too many protons.
atomic number the number under the element that tells its mass--mainly the number of protons plus neutrons
How many electrons are there in a non-charged element? electrons are the same number as protons
What did cyanobacteria do for development of life? They use photosynthesis to create oxygen. This made it easy for oxygen-breathing organisms to develop.
Why is cynobacteria important? Creates oxyagen by photosynthesis, produces the ozone layer in the atmosphere, and which makes it possible for oxagen breathing organisms to develop.
Created by: tboever17