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Chapter 12 Science
Chapter 12 Vocabulary
Question | Answer |
---|---|
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. |