Chapter 8 Part 2 Flashcards

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

24
Q

What happens to carbon-14 when you die?

A

No more carbon-14 in

25
Carbon-14 half-life equals
5,730 years
26
an archaeologist uses the changing ratio of carbon-14 to Carbon 12 to
Date the sample
27
Carbon-14 can you be used today for anything that was
Biological
28
Biological
Wood, paper, bone, shells, cloth
29
For creationists, carbon-14 dating on fossils have been determined for
Oil, coal, natural gas, fossil shells and bones, petrified wood, diamonds
30
Carbon-14 dating can be used for
Dating events from the historical past as well as those from very recent geologic history
31
Where is carbon-14 produced?
In the upper atmosphere as a consequence of cosmic ray bombardment
32
Geologic timescale
The division of geologic history into units of varying magnitude
33
Eons represent the
Greatest expanses of time
34
Phanerozoic
Visible life
35
Eons are divided into
Eras
36
Three eras of Phanerozoic are
Paleozoic, Mesozoic, Cenozoic
37
Eras are divided into
Periods
38
Periods are divided into
Epochs
39
Precambrian
Informal name for the eons that came before the current Phanerozoic eon
40
The primary problem in assigning numerical dates is the fact that
Not all rocks can be dated by radiometric methods