Science t3 old Flashcards
define absolute dating
define relative dating
Relative dating is a method used to determine the age of fossils or rocks by comparing them to other layers or objects
why are some isotopes are unstable
Some isotopes are unstable because their atomic nuclei have an imbalance between protons and neutrons. When this balance is off, the forces holding the nucleus together become weak, causing the isotope to become radioactive. Unstable isotopes will try to reach a more stable form by releasing energy in the form of radiation, a process called radioactive decay.
define half-life
the time that it takes for an isoptope to be halfed say if an isoptioope has a haldfd-life of 5 years after 5 years haqfl; of the ispotope willr emanion after ten half of that and so on
define carbon dating
Carbon dating, also known as radiocarbon dating, is a scientific method used to determine the age of an object containing organic material
explain how carbon dating works
Absorption of Carbon-14: While alive, organisms absorb carbon-14 from the atmosphere through processes like photosynthesis (in plants) or consumption (in animals).
Decay after Death: Once the organism dies, it stops absorbing carbon-14, and the isotope begins to decay at a known rate, called its half-life (about 5,730 years).
Measuring Decay: Scientists measure the amount of carbon-14 left in the sample. The less carbon-14 present, the older the sample.
Age Estimation: By comparing the ratio of carbon-14 to stable carbon isotopes (like carbon-12), scientists can calculate how many years have passed since the organism died, usually up to about 50,000 years ago.
define what an isotope is
An isotope is a version of an element that has the same number of protons but a different number of neutrons.
define carbon dating
explain how stratigraphy can be used to date fossils.
describe the geological timescale
explain how fluoride dating can be used to date fossils
identify the subatomic parts of an atom and where they are located
identify the charges of the different subatomic parts of an atom
explain the difference between mass number and atomic number of an atom
describe how isotopes release alpha, beta or gamma radiation
compare the properties of alpha, beta and gamma radiation
alculate the half-life of a sample using data or graphs
explain how the half-life of isotopes is used to tell time in radiometric dating
describe how the half-life of a radioisotope can be used to ‘tell time’
explain how the known half-life of radioisotopes can be used to determine the age of megafauna.
state when the megafauna lived and when they went extinct
define neutrons
Neutrons are subatomic particles found in the nucleus of an atom. They have no electric charge (neutral) and, along with protons, make up the mass of the atom. Neutrons help hold the nucleus together by balancing the repulsive forces between positively charged protons.
