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Flashcards in chapter 4 Deck (61):
1

What makes a stable nuclei

the force of attraction and repulsion are balanced

2

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

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

3

what makes a nuclei unstable?

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

4

Radiation

energy emitted by unstable nuclei to become more stable

5

radioisotopes

isotopes that emits radiation

6

Transmutation

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

7

Which elements are produced artificially?

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

8

How does emitting radiation help atoms be more stable?

an unstable nucleus forms a more stable, lower energy nucleus

9

What are the types of radiation?

alpha particles, beta particles, positron, Gamma rays

10

Alpha particles

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

11

beta particles

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

12

when do beta particles form?

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

13

positron

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

14

when is a positron produced?

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

15

How are gamma rays produced?

when a positron and an electron collides

16

ionization radiation

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

17

why is ionization energy harmful for humans

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

18

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

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

19

shielding

materials used to provide protection from radioactive sources

20

Alpha particles protection?

paper, skin, clothing

21

how do alpha particles travel?

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

22

Beta particle shielding

heavy clothes such as lab coats and gloves

23

which radiation particle has the largest mass?

alpha particles

24

Gamma rays protection

only dense shielding such as concrete and lead.

25

how far can gamma rays travel?

through bodies

26

How does one protect self from radiation?

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

27

What happens during radioactive decay?

unstable nucleus breaks down and releases high energy radiation

28

equation of a nuclear reaction:

Radioactive nucleus-->new nucleus + radiation

29

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

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

30

What happens to a radioactive nucleus during a beta decay?

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

31

What happens to a radioactive nucleus during a positron emission

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

32

What happens to a radioactive nucleus during a gamma emission?

the mass number and atomic number stays the same.

33

Most common source of alpha particle

Radium-226

34

most common source of beta particle

carbon-14

35

most common source of gamma particle

Technetium-99m

36

why are pure gamma emissions rare?

they accompany most alpha and beta radiation

37

transmutation

converting stable nonradioactive isotopes into radioactive ones

38

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

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

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

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

40

Geiger counter

instrument for measuring radiation (beta and gamma)

41

what unit measures disintegration per second of radiation?

Curie (c)
becquerel (Bq) (SI UNIT)

42

curie (c)

3.7 x 10^10 disintergrations per second

43

becquerel (Bq)

1 disintegration per second

44

what is disintegration?

activity of sample (radiation)

45

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

rad (radiation absorbed dose)
Gray (Gy) (SI UNIT)

46

1 Gy= ___rad

1 Gy= 100 rad

47

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

rem (radiation equivalent in humans)
sievert (sv) (SI UNIT)

48

formula to calculate rem?

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

49

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

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

50

1 sv= __rem
1 rem=__ mrem

1 sv= 100rem
1 rem= 1000 mrem

51

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

360 mrem /year

52

How does a geiger counter measure radiation?

uses ions produced by radiation to create an electrical current

53

why is radiation used in medicine?

they have short half lives

54

how much radiation is considered undetected on body?

25 rem

55

LD-50

lethal dose of radiation

56

Fission

Large nucleus split into smaller pieces releasing energy

57

Process of fission

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

Chain reaction

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

59

Fusion

2 small nuclei combine to form a larger nucleus

60

Is mass lost during fusion?

Yes, more energy is lost than fission

61

Why is fusion uncommon?

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