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Chemistry 132 > Chapter 21 > Flashcards

Chapter 21 Flashcards

1
Q

What is radioactivity?

A

It is the emission of subatomic particles or high-energy electromagnetic radiation by the nuclei of certain atoms. Atoms that emit radiation are said to be radioactive

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2
Q

What is phosphorenscence?

A

It is the long-lived emission of light by atoms or molecules that sometimes occurs after they absorb light

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3
Q

How are X-rays detected?

A

By their ability to penetrate matter and expose a photographic plate

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4
Q

Every atom of an element has the same number of _______, which is represented by the atomic number (Z)

A

Protons

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5
Q

Atoms of the same elements can have different numbers of _______, and are called isotopes

A

neutrons

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6
Q

How are isotopes identified?

A

By their mass number

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7
Q

How do we find the number of neutrons?

A

We subtract the atomic number from the mass number

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8
Q

How many protons and neutrons are there in the isotope 2713Al?

A

14 neutrons and 13 protons

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9
Q

What are the three types of radioactive rays discovered by Rutherford?

A

Alpha, beta, and gama

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10
Q

What are positrons and electron capture?

A

Positrons are similar to a positively charged electron emitted by unstable nuclei

Electron capture happens when a low energy electron is pulled into the nucleus

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11
Q

Gamma rays

A

Possess neither mass or change, it has the strongest penetrating power

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12
Q

Beta rays

A

It is symbolized as 0-1ß, it is a high speed electron

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13
Q

Alpha rays

A

It has the weakest penetrating power, it is the largest of all the components, it is symbolized as 42He

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14
Q

What is alpha decay?

A
  • Occurs when an unstable nucleus emits a particle composed of two protons and two neutrons
  • Most ionizing but least penetrating of the types of radioactivity
  • Loss of an alpha particle means

–the atomic number decreases by 2, and

–the mass number decreases by 4.

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15
Q

What is the ionizing power?

A

The ability of radiation to ionize other molecules and atoms

Of all types of radioactivity, alpha radiation has the highest ionizing power.

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16
Q

What is the penetrating power?

A

The ability to penetrate through matter

Alpha radiation does not easily penetrate into cells because it can be stopped by a sheet of paper, by clothing, or even by air.

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17
Q

What is beta decay?

A
  • Occurs when an unstable nucleus emits an electron
  • About 10 times more penetrating than α but only about half the ionizing ability
  • When an atom loses a β particle its

–atomic number increases by 1, and

–the mass number remains the same.

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18
Q

What is the gamma emission

A
  • Gamma (γ) rays are high-energy photons of light.
  • No loss of particles from the nucleus
  • No change in the composition of the nucleus

–Same atomic number and mass number

  • Least ionizing but most penetrating
  • Generally occurs after the nucleus undergoes some other type of decay and the remaining particles rearrange
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19
Q

If the room next door contains an alpha emitter, a beta emitter, and a gamma emitter, all with similar activities, which particles are you most likely to detect in the room you are in?

A

Gamma rays

20
Q

What is the positron emission?

A

•Positron has a charge of +1 and a negligible mass.

–Antiparticle of electron

  • Similar to beta particles in their ionizing and penetrating ability
  • When an atom loses a positron from the nucleus, its

–mass number remains the same, and

–its atomic number decreases by 1.

•Positrons result from a proton changing into a neutron.

It is similar to the beta particles but as the opposite

21
Q

What happens during an electron capture?

A
  • Occurs when an inner orbital electron is pulled into the nucleus
  • No particle emission, but atom changes

–Same result as positron emission

Only situation where the parent nuclide is affected and not the daughter nuclide

22
Q

What is the importance of the N/Z ratio?

A

•The ratio of neutrons: protons; is an important measure of the stability of the nucleus.

  • If the N/Z ratio is too high, neutrons are converted to protons via β decay.
  • If the N/Z ratio is too low, protons are converted to neutrons via positron emission or electron capture.

–Or via α decay, though not as efficiently

23
Q

What is the decay series?

A

Wehn all of the radioactive nuclides are produced one after the other until a stable nuclide is reached

24
Q

A Geiger-Muller counter and, a scintillation counter and a thermoluminiscent dosimeter are istruments important for what?

A

Detecting radioacitivity

25
Q

As most chemical reactions, the rate of radioactive change is affected by temperature.

A

False, it is not affected by temperature

26
Q

•The _______ the half-life, the more nuclei decay every second; therefore, we say the sample is ______”

A

Shorter; hotter

27
Q

Consider this graph representing the decay of a radioactive nuclide. What is the half-life of the nuclide?

a. 625 years
b. 1250 years
c. 2500 years
d. 3125 years

A

1250 years

28
Q

Which elements are used in radiometric dating?

A

potassium-40 to argon-40

29
Q

The radioactive decay of ________ is the single greatest source of human exposure to radiation

A

Radon

30
Q

The combination of two light nuclei to form a heavier nuclei is called

A

Nuclear fusion

31
Q

Identify the nuclide used to study bones.

A

technetium-99m

32
Q

Identify the radiotracer used to study the thyroid.

A

iodine-131

33
Q

A major medical use of fluorine-18 is _____.

A

in positron emission tomography (PET) to image the brain and heart

34
Q

What is nuclear fission?

A

when a large nucleus splits into two
smaller nuclei via reaction with
neutron

35
Q

What is nuclear fusion?

A

When small nuclei can be accelerated to
smash together to make a larger
nucleus.

36
Q

Who releases more energy, fusion or fission?

A

Fusion

37
Q

What is a chain reaction?

A

Occurs when a reactant in the process is also a product of the process. It is a self amplifying reaction.

38
Q

What is the critical mass?

A

The minimum amount of fissionable isotope needed to
sustain the chain reaction

39
Q

What are the three types of radiation effects?

A

acute radiation damage,
increased cancer risk, and genetic effects

40
Q

What is exposure?

A

the number of decay events to which a person is
exposed

41
Q

Dose

A

the amount of energy actually absorbed by body tissue

42
Q

What is s nuclide?

A

a particular isotope of an element

43
Q

Describe what changes occur during gamma ray emission.

A

The mass number and atomic number do not change.

44
Q

Which type of radioactivity changes the mass of the isotope the most?

A

alpha particle

45
Q
A

Chemistry 132 (10 decks)

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