chapter 4 Flashcards

1
Q

What makes a stable nuclei

A

the force of attraction and repulsion are balanced

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2
Q

which elements usually have a stable nuclei, and which don’t

A

element below atomic number #19 usually have a stable nuclei, elements atomic number #20 and above usually don’t have stable nuclei

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3
Q

what makes a nuclei unstable?

A

too many or too few protons compared to number of neutrons therefore the forces are unbalanced

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4
Q

Radiation

A

energy emitted by unstable nuclei to become more stable

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5
Q

radioisotopes

A

isotopes that emits radiation

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6
Q

Transmutation

A

change in number of protons in nucleus (atom of an element converted to a different element)

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7
Q

Which elements are produced artificially?

A

elements #93 or higher on the periodic table are produced in nuclear labs

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8
Q

How does emitting radiation help atoms be more stable?

A

an unstable nucleus forms a more stable, lower energy nucleus

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9
Q

What are the types of radiation?

A

alpha particles, beta particles, positron, Gamma rays

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10
Q

Alpha particles

A

identical to helium nucleus (2 protons, 2 neutrons, mass number 4, atomic number 2, charge of 2+

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11
Q

beta particles

A

high energy electron with a charge of 1-, mass number 0

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12
Q

when do beta particles form?

A

when a neutron in an unstable nucleus changes to a proton and an electron.

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13
Q

positron

A

positive 1+ charge with a mass of 0, it is an antimatter

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14
Q

when is a positron produced?

A

it is produced by the unstable nucleus when a proton is transformed into a neutron and a positron

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15
Q

How are gamma rays produced?

A

when a positron and an electron collides

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16
Q

ionization radiation

A

when radiation hits molecules in its way, electrons may be knocked away forming unstable ions

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17
Q

why is ionization energy harmful for humans

A

if it passes through human body, it might interact with water molecules removing electrons and producing H20+

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18
Q

Which type of cells are most sensitive to ionization radiation? and examples?

A

cells that undergo rapid cell division, such as bone marrow, skin, reproductive organs, cells of growing children and cancer cells

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19
Q

shielding

A

materials used to provide protection from radioactive sources

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20
Q

Alpha particles protection?

A

paper, skin, clothing

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21
Q

how do alpha particles travel?

A

in the air for a few cm before they collide with air molecules , acquire electrons and become helium

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22
Q

Beta particle shielding

A

heavy clothes such as lab coats and gloves

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23
Q

which radiation particle has the largest mass?

A

alpha particles

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24
Q

Gamma rays protection

A

only dense shielding such as concrete and lead.

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25
Q

how far can gamma rays travel?

A

through bodies

26
Q

How does one protect self from radiation?

A

greater distance from radioactive source and less exposure/time with radioactive source

27
Q

What happens during radioactive decay?

A

unstable nucleus breaks down and releases high energy radiation

28
Q

equation of a nuclear reaction:

A

Radioactive nucleus–>new nucleus + radiation

29
Q

What happens to a radioactive nucleus during an alpha decay reaction?

A

The mass of the nucleus goes down by 4 and atomic number (protons) goes down by 2.

30
Q

What happens to a radioactive nucleus during a beta decay?

A

the mass stays the same, the atomic number (protons) increases by 1.

31
Q

What happens to a radioactive nucleus during a positron emission

A

mass number stays the same, the atomic number (protons) goes down by 1

32
Q

What happens to a radioactive nucleus during a gamma emission?

A

the mass number and atomic number stays the same.

33
Q

Most common source of alpha particle

A

Radium-226

34
Q

most common source of beta particle

A

carbon-14

35
Q

most common source of gamma particle

A

Technetium-99m

36
Q

why are pure gamma emissions rare?

A

they accompany most alpha and beta radiation

37
Q

transmutation

A

converting stable nonradioactive isotopes into radioactive ones

38
Q

What is different about all atomic numbers 92 and above? and how?

A

they are created in labs through transmutation by bombarding high speed particles (protons, neutrons and small nuclei) and when absorbed by stable nucleus, radioactive isotopes are created.

39
Q

How and why is Technetium-99m used in nuclear medicine?

A

for diagnostic purposes (brain tumors, spleen and liver examinations) since they pass through the body

40
Q

Geiger counter

A

instrument for measuring radiation (beta and gamma)

41
Q

what unit measures disintegration per second of radiation?

A

Curie (c)

becquerel (Bq) (SI UNIT)

42
Q

curie (c)

A

3.7 x 10^10 disintergrations per second

43
Q

becquerel (Bq)

A

1 disintegration per second

44
Q

what is disintegration?

A

activity of sample (radiation)

45
Q

what unit measures amount of radiation absorbed by a g of a material?

A

rad (radiation absorbed dose)

Gray (Gy) (SI UNIT)

46
Q

1 Gy= ___rad

A

1 Gy= 100 rad

47
Q

what unit measures the biological effects of different kinds of radiation?

A

rem (radiation equivalent in humans)

sievert (sv) (SI UNIT)

48
Q

formula to calculate rem?

A

biological damage (rem)= absorbed dose (rad) x factor (of radiation)

49
Q
what is the factor of:
gamma particles:
beta particles:
protons:
neutrons:
alpha particles:
A

Gamma, beta: 1
high energy proton, neutron: 10
alpha: 20

50
Q

1 sv= __rem

1 rem=__ mrem

A

1 sv= 100rem

1 rem= 1000 mrem

51
Q

how much radiation does an average person in the US get annually?

A

360 mrem /year

52
Q

How does a geiger counter measure radiation?

A

uses ions produced by radiation to create an electrical current

53
Q

why is radiation used in medicine?

A

they have short half lives

54
Q

how much radiation is considered undetected on body?

A

25 rem

55
Q

LD-50

A

lethal dose of radiation

56
Q

Fission

A

Large nucleus split into smaller pieces releasing energy

57
Q

Process of fission

A

Releases neutrons and large amounts of gamma radiation and energy

  1. Neutron collides with nucleus (of uranium)
  2. Nucleus becomes unstable and splits into smaller nuclei
58
Q

Chain reaction

A

Fission reaction that will continue once initiated by high energy neutron bombarding a heavy nucleus

59
Q

Fusion

A

2 small nuclei combine to form a larger nucleus

60
Q

Is mass lost during fusion?

A

Yes, more energy is lost than fission

61
Q

Why is fusion uncommon?

A

It requires the temperature of 100,000,000 C for hydrogen nuclei to undergo fusion