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Earth Science Unit 2 > Chapter 8 Part 2 > Flashcards

Chapter 8 Part 2 Flashcards

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1
Q

Isotope

A

An element with a variable number of neutrons in the nucleus

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2
Q

During radioactive decay an unstable isotope (parent)

A

Ejects material from its nucleus to become a daughter isotope

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3
Q

Three types of radioactive decay

A

Alpha decay
Beta emission
electron capture

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4
Q

Alpha decay

A

The parent ejects an alpha particle, made of two protons and two neutrons, from the nucleus

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5
Q

Beta emission

A

The parent emits a beta particle from the nucleus

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6
Q

Electron capture

A

An electron collides with the nucleus, converting a proton into a neutron

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7
Q

Radioactivity

A

Nuclei spontaneously break apart

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8
Q

An unstable isotope is referred to as the

A

Parent

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9
Q

Most important result of discovery of radioactivity

A

It provides a reliable method of calculating the ages of rocks and minerals that contain particular radioactive isotopes

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10
Q

Radiometric dating

A

Procedure of calculating the ages of rocks and minerals containing radioactive isotopes

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11
Q

Why is radiometric dating reliable?

A

The rates of decay for many isotopes have been precisely measured and do not vary under the physical conditions that exist in Earth’s outer layers

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12
Q

Half-life

A

The time that it takes for half of a radioactive sample to decay to its final, stable daughter product

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13
Q

As the percentage of radioactive parent atoms ____, The proportion of stable daughter atoms ___.

A

Declines, rises

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14
Q

Rules for a radioactive dating

A

1- Number of parent and daughter isotopes only changes by radioactive decay (closed system)
2-the amount of daughter at beginning is either zero or can be determined
3-The decay rate (half-life) has not changed over time
4-No errors in collection or analysis

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15
Q

Date=

A

Number of half-livesXrate

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16
Q

What can be dated?

A

Igneous (lava, ashes, intrusive)

Metamorphic (especially high-grade)

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17
Q

Since you can’t date sedimentary rocks, geologists do what?

A

Make brackets using surrounding rocks

18
Q

The Carbon 14 system

A
  • Carbon-14 is formed in the atmosphere all the time.

- A neutron collides with a nitrogen atom forming carbon-14

19
Q

Carbon-14 will convert back to nitrogen via

A

Beta emissiom

20
Q

Carbon-14 combines with oxygen to form

A

Carbon dioxide 14

21
Q

Plants take in carbon dioxide 14 and make

A

Leaves, sugar, fruits and flowers which gets eaten by animals, protists and fungi

22
Q

One carbon-14:

A

1 trillion Carbon 12

23
Q

Carbon-14 in is _____ with Carbon-14 out

A

Balanced

24
Q

What happens to carbon-14 when you die?

A

No more carbon-14 in

25
Q

Carbon-14 half-life equals

A

5,730 years

26
Q

an archaeologist uses the changing ratio of carbon-14 to Carbon 12 to

A

Date the sample

27
Q

Carbon-14 can you be used today for anything that was

A

Biological

28
Q

Biological

A

Wood, paper, bone, shells, cloth

29
Q

For creationists, carbon-14 dating on fossils have been determined for

A

Oil, coal, natural gas, fossil shells and bones, petrified wood, diamonds

30
Q

Carbon-14 dating can be used for

A

Dating events from the historical past as well as those from very recent geologic history

31
Q

Where is carbon-14 produced?

A

In the upper atmosphere as a consequence of cosmic ray bombardment

32
Q

Geologic timescale

A

The division of geologic history into units of varying magnitude

33
Q

Eons represent the

A

Greatest expanses of time

34
Q

Phanerozoic

A

Visible life

35
Q

Eons are divided into

A

Eras

36
Q

Three eras of Phanerozoic are

A

Paleozoic, Mesozoic, Cenozoic

37
Q

Eras are divided into

A

Periods

38
Q

Periods are divided into

A

Epochs

39
Q

Precambrian

A

Informal name for the eons that came before the current Phanerozoic eon

40
Q

The primary problem in assigning numerical dates is the fact that

A

Not all rocks can be dated by radiometric methods

Earth Science Unit 2 (4 decks)

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