Chapter 21

Question 1

What is radioactivity?

Answer 1

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

Question 2

What is phosphorenscence?

Answer 2

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

Question 3

How are X-rays detected?

Answer 3

By their ability to penetrate matter and expose a photographic plate

Question 4

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

Answer 4

Protons

Question 5

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

Answer 5

neutrons

Question 6

How are isotopes identified?

Answer 6

By their mass number

Question 7

How do we find the number of neutrons?

Answer 7

We subtract the atomic number from the mass number

Question 8

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

Answer 8

14 neutrons and 13 protons

Question 9

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

Answer 9

Alpha, beta, and gama

Question 10

What are positrons and electron capture?

Answer 10

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

Question 11

Gamma rays

Answer 11

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

Question 12

Beta rays

Answer 12

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

Question 13

Alpha rays

Answer 13

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

Question 14

What is alpha decay?

Answer 14

• 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.

Question 15

What is the ionizing power?

Answer 15

The ability of radiation to ionize other molecules and atoms

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

Question 16

What is the penetrating power?

Answer 16

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.

Question 17

What is beta decay?

Answer 17

• 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.

Question 18

What is the gamma emission

Answer 18

• 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

Question 19

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?

Answer 19

Gamma rays

Question 20

What is the positron emission?

Answer 20

•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

Question 21

What happens during an electron capture?

Answer 21

• 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

Question 22

What is the importance of the N/Z ratio?

Answer 22

•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

Question 23

What is the decay series?

Answer 23

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

Question 24

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

Answer 24

Detecting radioacitivity

Question 25

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

Answer 25

False, it is not affected by temperature

Question 26

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

Answer 26

Shorter; hotter

Question 27

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

Answer 27

1250 years

Question 28

Which elements are used in radiometric dating?

Answer 28

potassium-40 to argon-40

Question 29

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

Answer 29

Radon

Question 30

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

Answer 30

Nuclear fusion

Question 31

Identify the nuclide used to study bones.

Answer 31

technetium-99m

Question 32

Identify the radiotracer used to study the thyroid.

Answer 32

iodine-131

Question 33

A major medical use of fluorine-18 is \_\_\_\_\_.

Answer 33

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

Question 34

What is nuclear fission?

Answer 34

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

Question 35

What is nuclear fusion?

Answer 35

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

Question 36

Who releases more energy, fusion or fission?

Answer 36

Fusion

Question 37

What is a chain reaction?

Answer 37

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

Question 38

What is the critical mass?

Answer 38

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

Question 39

What are the three types of radiation effects?

Answer 39

acute radiation damage, increased cancer risk, and genetic effects

Question 40

What is exposure?

Answer 40

the number of decay events to which a person is exposed

Question 41

Dose

Answer 41

the amount of energy actually absorbed by body tissue

Question 42

What is s nuclide?

Answer 42

a particular isotope of an element

Question 43

Describe what changes occur during gamma ray emission.

Answer 43

The mass number and atomic number do not change.

Question 44

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

Answer 44

alpha particle