1.5 C: Geology = the Changing Earth 1.5 Pinpointing Time Flashcards
What is radioactivity?
The emission of energy from the nuclei of unstable atoms as they change to become more stable forms.
This concept was first named by Marie Curie.
Who discovered radioactivity?
Marie Curie.
Curie made significant contributions to the understanding of radioactivity during the late nineteenth century.
What did Ernest Rutherford discover about radioactive materials?
The energy emitted from radioactive materials was in the form of high-speed particles.
Rutherford’s work was conducted at McGill University in Montreal.
What method did Rutherford use to measure radiation intensity?
By detecting the number of particles emitted per second.
This quantification helped in understanding the behavior of radioactive materials.
During which centuries were the discoveries related to radioactivity made?
Late nineteenth century and early twentieth century.
This period marked significant advancements in the field of physics.
Fill in the blank: The discovery of radioactivity attracted the interest of a bright young physicist named _______.
Ernest Rutherford.
True or False: Marie Curie was the first to discover isotopes of certain elements emitting rays invisible to the eye.
True.
Curie’s research led to the identification of radioactivity as a phenomenon.
What is radioactive decay?
The disintegration of an unstable atom, which results in the release of energy in the form of radiation.
Radioactive decay is a natural process that occurs in unstable isotopes.
What is half-life?
The time taken for half of a radioactive sample to decay.
Half-life is a constant characteristic of a particular isotope.
True or False: The half-life is different for each isotope.
True
Each isotope has a unique half-life that determines how quickly it decays.
Fill in the blank: A half-life is a _______ characteristic of a particular isotope.
constant
What happens to the amount of a radioactive sample after one half-life?
It is reduced to 50% of the original amount.
This reduction continues with each subsequent half-life.
What speed did Rutherford measure for alpha particles released by radioactive decay?
24,000 km/s
What did Rutherford demonstrate about the kinetic energy of alpha particles?
It could be transformed into heat.
What is believed to be the ongoing source of heat that drives convection currents in the Earth’s mantle?
Radioactive decay in Earth’s core
True or False: Rutherford showed that kinetic energy from radioactive decay could not be transformed into heat.
False
Fill in the blank: Radioactive decay in Earth’s core is the ongoing source of heat that drives _______ in the mantle.
convection currents
What speed did Rutherford measure for alpha particles released by radioactive decay?
24,000 km/s
What did Rutherford demonstrate about the kinetic energy of alpha particles?
It could be transformed into heat.
What is believed to be the ongoing source of heat that drives convection currents in the Earth’s mantle?
Radioactive decay in Earth’s core
True or False: Rutherford showed that kinetic energy from radioactive decay could not be transformed into heat.
False
Fill in the blank: Radioactive decay in Earth’s core is the ongoing source of heat that drives _______ in the mantle.
convection currents
What happens to radon-220 atoms?
They decay spontaneously into polonium
This process is part of radioactive decay.
What is released during the decay of radon-220?
Energy in the form of radiation
This radiation is a characteristic of radioactive decay.
Who was led to the discovery of the instability of radon-220?
Rutherford
Rutherford’s work in radioactivity contributed to our understanding of atomic transformations.
What did Rutherford’s findings remind him of?
The alchemists
Alchemists aimed to transform common elements into precious ones like gold.
What is a parent isotope?
The original unstable atom
Parent isotopes undergo decay to form daughter isotopes.
What is a daughter isotope?
The more stable product formed from the parent isotope
Daughter isotopes are the result of radioactive decay.
Define isotope.
A particular variety of an element as defined by its atomic mass
Isotopes can vary in stability and radioactive properties.
True or False: Rutherford discovered a method to transmute lead into gold.
False
Rutherford did not find a way to make gold from other atoms.
What is a half-life in the context of radioactive decay?
The time it takes for half of a radioactive sample to decay.
Half-lives are constant intervals of time that apply to all radioactive elements.
True or False: The shape of the decay curve for radioactive elements changes with varying conditions like heat or pressure.
False.
The decay curve remains the same regardless of external conditions.
What did Rutherford and Curie discover about radioactive samples?
The decay process occurs at a fixed rate, represented by half-life.
Their findings indicated that the decay process is consistent and predictable.
Fill in the blank: The decay of radioactive elements can be used to measure the time passed since a _______ or fossil has formed.
[rock]
This is possible due to the consistent nature of radioactive decay.
List the scientists mentioned in relation to radioactive dating.
- Rutherford
- Curie
These scientists contributed significantly to the understanding of radioactive decay.
What is the significance of radioactive decay in geology?
It allows for the dating of rocks and fossils based on fixed decay rates.
This technique is crucial for understanding geological time scales.
What does the term ‘radioactive dating’ refer to?
A method used to determine the age of rocks and fossils through their radioactive decay rates.
This technique relies on the known half-lives of radioactive isotopes.
Explain why counting atoms is considered hard in the context of radioactive dating.
Because accurate measurement of the number of atoms in a sample is complex and challenging.
This complexity can affect the precision of dating results.
Who discovered the properties of radioactive decay?
Rutherford
What did Rutherford realize about radioactive decay?
It could be used to determine the age of rocks and Earth
What prevented Rutherford from successfully applying his ideas about radioactive decay?
Limited technology available to him
What have scientists developed to count the number of each type of atom in a sample?
Very precise methods
What is the significant breakthrough in measuring isotopes that occurred just after World War I?
Invention of the mass spectrometer
What can a mass spectrometer detect in a sample of rock?
Elements and their isotopes
What is determined using a mass spectrometer that is essential for radioactive dating?
Percentage of each isotope present in the sample
Fill in the blank: The invention of the _______ was a breakthrough for determining isotopes in samples.
mass spectrometer
True or False: Rutherford was successful in applying his thinking about radioactive decay to date rocks.
False
What are some of the world’s oldest rocks called?
Zircons
Zircons are tiny crystals found embedded in other rocks.
Where are some of the oldest zircons found?
Acasta Gneiss Rock Formation in the Northwest Territories of Canada
Acasta Gneiss is noted for containing ancient zircons.
What element do zircons contain that makes them useful for dating?
Uranium
Uranium is used in radiometric dating due to its decay properties.
What is a key characteristic of zircons that aids in radiometric dating?
They are amazingly durable
Zircons can withstand extreme conditions, such as melting rock.
What happens to the uranium clock when a zircon forms?
It is set at zero
From this point, uranium begins to decay, allowing for age estimation.
What can uranium be used to date besides zircons?
Volcanic ash layers
Knowing the age of volcanic ash helps estimate the ages of surrounding rock layers.
True or False: Uranium decay can be used to date layers of rock that cannot be dated directly.
True
By knowing the age of volcanic ash, scientists can infer ages of adjacent layers.
Fill in the blank: The Acasta Gneiss Rock Formation is located in the _______.
Northwest Territories
This region in Canada contains some of the oldest known rocks.
What is the geological significance of the age of the rocks in Acasta Gneiss?
They are about 4 billion years old
This makes them some of the oldest rocks on Earth.
