17. World Of Isotopes

Question 1

What are radioisotopes?

Answer 1

Mother nuclides disintegrate to daughter nuclides at a given half-life

When they decay, there’s energy release/ radiation

Question 2

What are stable isotopes

Answer 2

Disintegration has not been observed yet

All visible matter is made up of stable isotopes

Question 3

What are two types of isotopes?

Answer 3

Radioisotope and stable isotope

Question 4

Describe Isotopes, Isobars, Isotones

Answer 4

Isotope- same proton number, different mass number and neutron number

Isobar- same mass number, different proton number and neutron number

Isotones- same neutron number, different proton and mass number

Question 5

Describe the chart of nuclides

Answer 5

Each line represents an element
Each square represents an isotope
Color represents mode of decay

Question 6

Radioisotopes are more common than stable isotopes. True or false

Answer 6

True

Question 7

Define atomic weight

Answer 7

Atomic weight of an element from a specified source is the ratio of the average mass per atom of the element to 1/12 of the mass of an atom of Carbon-12

Question 8

Define standard atomic weight

Answer 8

IUPAC’s recommend for the element

Question 9

What are mononuclidic and polynuclidic elements?

Answer 9

Made up is a single stable isotope
Standard atomic weight equals mass of the isotope

Poly- blend of up to 8 stable isotopes
Standard atomic weight = sum of nuclides masses WEIGHTED by the abundances of individual isotopes

Question 10

Define mass defect

Answer 10

Mass of nucleus is less than mass of individual protons and neutrons nuclear fusion: difference in mass is released as energy

Question 11

Define the Oddo-Harkins rule

Answer 11

Elements with an even number of protons (eg C) are mostly abundant than elements with an odd number of protons (eg N)

Question 12

Nitrogen (Z=7) is more abundant than Carbon (Z=6). T or F

Answer 12

False. Even more

Question 13

All isotopes with Z>= 83 are unstable. T or F

Answer 13

True

Question 14

All elements with Z<= 82 are unstable. T or F

Answer 14

False. All elements with Z<= 82 have at least one stable isotope

Question 15

Describe the valley of stability

Answer 15

defined by the right ratio of neutron to proton
radioisotopes try to reach the valley of stability through radioactive decay
mode of decay depends on neutron to proton ratio

Question 16

Describe Alpha decay

Answer 16

emission of alpha particle=helium nucleus
Z>83

238U - 234Th + 4He
92 90 2

Question 17

Describe Beta decay

Answer 17

neutron to proton
40K = 40 Ca + e- + v
19 20

Question 18

Describe Positron decay (beta decay)

Answer 18

proton to neutron
40K = 40 Ar + e+ +v
19 18

Question 19

Describe electron capture

Answer 19

inverse Beta decay

40K + e- = 40Ar
19 18

Question 20

Describe gamma rays

Answer 20

no form of decay = does not affect the atomic mass and number
occurs with other forms of decay
discrete energy, characteristic for nuclide

Question 21

Radioisotopes are harmful. T or F

Answer 21

False. The decay of the isotopes cause harms not the radioisotope itself. When the machine beeps, it measures the decay of the isotope.

Question 22

Give examples of natural background radiation

Answer 22

Thorium and Uranium are present in rocks and minerals

Th decay to 208 Pb
Ur decay to 206 Pb

Potassium -40 decay to Ca-40
present in traces for every natural potassium

Cosmic radition
-through interaction of cosmic rays with gases in the atmosphere

Question 23

Why is radon harmful?

Answer 23

It is a gas and hence, it can leave the rock, leaving us exposed to breathing it in

Question 24

Rank the types of radioactive decay from least ionizing to most ionizing

Answer 24

Gamma
Beta
Alpha decay

Question 25

Rank the types of radioactive decay from least penetrating to most penetrating

Answer 25

Alpha decay Beta Gamma

Question 26

What is the unit for activity?

Answer 26

Bequerel (Bq) = 1 nuclear disintegration per second

Question 27

What is the unit for Absorbed dose?

Answer 27

Gray (Gy) = 1 J of absorbed energy per kg tissue (SI-Unit) 1 Gy = 100 rad

Question 28

What is the unit for effective dose?

Answer 28

Sievert (Sv)

Question 29

Define effective dose

Answer 29

multiplication of Absorbed dose with radiation weighting factor (Wr) (considers tissue and type of radiation)

Question 30

Match these three unit symbols to its definition: | Sv, Bq, Gy

Answer 30

Sievert -effective dose Bequerel - activity Gray - absorbed dose

Question 31

How much radiation can u get from 1) chest x-ray 2) average effective dose from natural bg radiation 3) one set of panoramic dental radiograph 4) single full body CT scan 5) hourly effective dose in direct vicinity to CHernobyl core and Fukushima directly after the accident?

Answer 31

0.07 mSv 2.4 5-10 10 to 30 300 and 1000

Question 32

What is the average effective dose obtained from natural background radiation?

Answer 32

2.4 mSv

Question 33

Who were the founding fathers of Nuclear fission?

Answer 33

Otto Hahn, Lise Mietner, Fritz Strassmann

Question 34

Comparee Nuclear fission and nuclear fusion

Answer 34

Nuclear fission is the splitting of a nucleus into smaller nuclei which are radioactive 2 or more neutrons may be releaased as well. Some energy may also be released The released neutrons may hit other uranium nuclei and cause them to split. Even more neutrons are released which in turn can split more nuclei. This is called a chain reaction Nuclear fission involves two atomic nuclei joining to form a large nucleus Energy is released when this happens The Sun and the stars use nuclear fusion to release energy

Question 35

What is the working principle of gas-filled detectors?

Answer 35

filled the container with gas ionize the gas along radiation path accelerate primary ions by voltage and produce avalanche of ions

Question 36

what is the proportional counter for?

Answer 36

Used to control voltage so that current is proportional to the energy of incoming particles.

Question 37

What is the Geiger-Muller counter for?

Answer 37

runs at higher voltage each single partcile produces an avalanche Limitations: cannot differentiate between decay types and particle energies Advantage: significant detector deadtime but less suitable for high count rates.

Question 38

How is analysis carried out and how do you determine the element's specific activity?

Answer 38

sample is bombarded by high neutron influx elements capture neutron and become radioactive analysis by gamma-spec element concentration neutron capture radiation time half-life of radioisotope

Question 39

What are the advantages of Neutron activation analysis?

Answer 39

multiple-element for bulk analysis minimum sample prep analytical precision 1-5%

Question 40

What is the working principle of X-ray fluorescence?

Answer 40

x-ray kicks out an inner electron electron from an outer shell fills in the gap emission of discrete energy