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1. Science 20 > C: Geology = the Changing Earth 1.5 Pinpointing Time > Flashcards

C: Geology = the Changing Earth 1.5 Pinpointing Time Flashcards

1
Q

What is radioactivity?

A

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.

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2
Q

Who discovered radioactivity?

A

Marie Curie.

Curie made significant contributions to the understanding of radioactivity during the late nineteenth century.

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3
Q

What did Ernest Rutherford discover about radioactive materials?

A

The energy emitted from radioactive materials was in the form of high-speed particles.

Rutherford’s work was conducted at McGill University in Montreal.

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4
Q

What method did Rutherford use to measure radiation intensity?

A

By detecting the number of particles emitted per second.

This quantification helped in understanding the behavior of radioactive materials.

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5
Q

During which centuries were the discoveries related to radioactivity made?

A

Late nineteenth century and early twentieth century.

This period marked significant advancements in the field of physics.

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6
Q

Fill in the blank: The discovery of radioactivity attracted the interest of a bright young physicist named _______.

A

Ernest Rutherford.

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7
Q

True or False: Marie Curie was the first to discover isotopes of certain elements emitting rays invisible to the eye.

A

True.

Curie’s research led to the identification of radioactivity as a phenomenon.

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8
Q

What is radioactive decay?

A

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.

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9
Q

What is half-life?

A

The time taken for half of a radioactive sample to decay.

Half-life is a constant characteristic of a particular isotope.

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10
Q

True or False: The half-life is different for each isotope.

A

True

Each isotope has a unique half-life that determines how quickly it decays.

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11
Q

Fill in the blank: A half-life is a _______ characteristic of a particular isotope.

A

constant

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12
Q

What happens to the amount of a radioactive sample after one half-life?

A

It is reduced to 50% of the original amount.

This reduction continues with each subsequent half-life.

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13
Q

What speed did Rutherford measure for alpha particles released by radioactive decay?

A

24,000 km/s

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14
Q

What did Rutherford demonstrate about the kinetic energy of alpha particles?

A

It could be transformed into heat.

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15
Q

What is believed to be the ongoing source of heat that drives convection currents in the Earth’s mantle?

A

Radioactive decay in Earth’s core

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16
Q

True or False: Rutherford showed that kinetic energy from radioactive decay could not be transformed into heat.

A

False

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17
Q

Fill in the blank: Radioactive decay in Earth’s core is the ongoing source of heat that drives _______ in the mantle.

A

convection currents

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18
Q

What speed did Rutherford measure for alpha particles released by radioactive decay?

A

24,000 km/s

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19
Q

What did Rutherford demonstrate about the kinetic energy of alpha particles?

A

It could be transformed into heat.

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20
Q

What is believed to be the ongoing source of heat that drives convection currents in the Earth’s mantle?

A

Radioactive decay in Earth’s core

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21
Q

True or False: Rutherford showed that kinetic energy from radioactive decay could not be transformed into heat.

A

False

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22
Q

Fill in the blank: Radioactive decay in Earth’s core is the ongoing source of heat that drives _______ in the mantle.

A

convection currents

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23
Q

What happens to radon-220 atoms?

A

They decay spontaneously into polonium

This process is part of radioactive decay.

24
Q

What is released during the decay of radon-220?

A

Energy in the form of radiation

This radiation is a characteristic of radioactive decay.

25
Q

Who was led to the discovery of the instability of radon-220?

A

Rutherford

Rutherford’s work in radioactivity contributed to our understanding of atomic transformations.

26
Q

What did Rutherford’s findings remind him of?

A

The alchemists

Alchemists aimed to transform common elements into precious ones like gold.

27
Q

What is a parent isotope?

A

The original unstable atom

Parent isotopes undergo decay to form daughter isotopes.

28
Q

What is a daughter isotope?

A

The more stable product formed from the parent isotope

Daughter isotopes are the result of radioactive decay.

29
Q

Define isotope.

A

A particular variety of an element as defined by its atomic mass

Isotopes can vary in stability and radioactive properties.

30
Q

True or False: Rutherford discovered a method to transmute lead into gold.

A

False

Rutherford did not find a way to make gold from other atoms.

31
Q

What is a half-life in the context of radioactive decay?

A

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.

32
Q

True or False: The shape of the decay curve for radioactive elements changes with varying conditions like heat or pressure.

A

False.

The decay curve remains the same regardless of external conditions.

33
Q

What did Rutherford and Curie discover about radioactive samples?

A

The decay process occurs at a fixed rate, represented by half-life.

Their findings indicated that the decay process is consistent and predictable.

34
Q

Fill in the blank: The decay of radioactive elements can be used to measure the time passed since a _______ or fossil has formed.

A

[rock]

This is possible due to the consistent nature of radioactive decay.

35
Q

List the scientists mentioned in relation to radioactive dating.

A
  • Rutherford
  • Curie

These scientists contributed significantly to the understanding of radioactive decay.

36
Q

What is the significance of radioactive decay in geology?

A

It allows for the dating of rocks and fossils based on fixed decay rates.

This technique is crucial for understanding geological time scales.

37
Q

What does the term ‘radioactive dating’ refer to?

A

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.

38
Q

Explain why counting atoms is considered hard in the context of radioactive dating.

A

Because accurate measurement of the number of atoms in a sample is complex and challenging.

This complexity can affect the precision of dating results.

39
Q

Who discovered the properties of radioactive decay?

A

Rutherford

40
Q

What did Rutherford realize about radioactive decay?

A

It could be used to determine the age of rocks and Earth

41
Q

What prevented Rutherford from successfully applying his ideas about radioactive decay?

A

Limited technology available to him

42
Q

What have scientists developed to count the number of each type of atom in a sample?

A

Very precise methods

43
Q

What is the significant breakthrough in measuring isotopes that occurred just after World War I?

A

Invention of the mass spectrometer

44
Q

What can a mass spectrometer detect in a sample of rock?

A

Elements and their isotopes

45
Q

What is determined using a mass spectrometer that is essential for radioactive dating?

A

Percentage of each isotope present in the sample

46
Q

Fill in the blank: The invention of the _______ was a breakthrough for determining isotopes in samples.

A

mass spectrometer

47
Q

True or False: Rutherford was successful in applying his thinking about radioactive decay to date rocks.

A

False

48
Q

What are some of the world’s oldest rocks called?

A

Zircons

Zircons are tiny crystals found embedded in other rocks.

49
Q

Where are some of the oldest zircons found?

A

Acasta Gneiss Rock Formation in the Northwest Territories of Canada

Acasta Gneiss is noted for containing ancient zircons.

50
Q

What element do zircons contain that makes them useful for dating?

A

Uranium

Uranium is used in radiometric dating due to its decay properties.

51
Q

What is a key characteristic of zircons that aids in radiometric dating?

A

They are amazingly durable

Zircons can withstand extreme conditions, such as melting rock.

52
Q

What happens to the uranium clock when a zircon forms?

A

It is set at zero

From this point, uranium begins to decay, allowing for age estimation.

53
Q

What can uranium be used to date besides zircons?

A

Volcanic ash layers

Knowing the age of volcanic ash helps estimate the ages of surrounding rock layers.

54
Q

True or False: Uranium decay can be used to date layers of rock that cannot be dated directly.

A

True

By knowing the age of volcanic ash, scientists can infer ages of adjacent layers.

55
Q

Fill in the blank: The Acasta Gneiss Rock Formation is located in the _______.

A

Northwest Territories

This region in Canada contains some of the oldest known rocks.

56
Q

What is the geological significance of the age of the rocks in Acasta Gneiss?

A

They are about 4 billion years old

This makes them some of the oldest rocks on Earth.

1. Science 20 (52 decks)

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