unit 12 - nuclear chem

Question 1

radioisotopes

Answer 1

• unstable isotopes
• versions of an element that are NOT stable

Question 2

all unstable isotopes are…

Answer 2

RADIOACTIVE

Question 3

the nucleus will spontaneousy break down by a means of

Answer 3

radioactive decay

Question 4

decay occurs until

Answer 4

a stable isotope of an element forms

Question 5

table N

Answer 5

• short list (not all) with versions of certain elements that are radioactive
• ex: C-14 & N-16

Question 6

remember isotopes are named from…

Answer 6

• their numbers!!
• the mass numbers are given to you BUT NOT the proton number because that is periodic table

Question 7

radioactivity: unstable/radioactive atom

Answer 7

= spontaneously decay

Question 8

large neutron to proton ratio

Answer 8

more than 1:1 (heavy nucleus)

Question 9

atomic number what and greater is what

Answer 9

atomic number 83 or greater
- all isotopes of these elements are unstable, no version is stable

Question 10

unstable atoms emit

Answer 10

energy and particles

Question 11

transmutation

Answer 11

decay causes the nucleus of an atom to disintegrate and change into the nucleus of another element

Question 12

natural transmutation

Answer 12

• spontaneous decay
• when the nucleus of an unstable atom/radioisotope (without intervention) breaks down naturally or by itself
• in the end the nucleus will trans-mutate or turn into the nucleus of another element

Question 13

artificial transmutation

Answer 13

forced or nonspontaneous decay
- a change in the nucleus of an atom brought about by bombarding the nucleus with high energy particles

Question 14

there are 4 types of nuclear emissions

Answer 14

1) alpha particles
2) beta particles
3) positron particles
4) gamma rays

**use Table O for name, notation, and symbol

Question 15

alpha particles

Answer 15

4 <- mass
He (same as He-4 atom in mass and charge
2 <- charge but they are not the same thing)

• alpha particles have the lowest penetrating power

Question 16

what has the lowest penetrating power

Answer 16

alpha particles
- they can be stopped by a ream of paper

Question 17

beta particles

Answer 17

0 <- mass
e (same as electron in mass and charge but
-1 <- charge not an electron)

• beta particles have moderate penetrating power, they can be stopped by a brick

Question 18

positron

Answer 18

0
e
+1
- think of it like a positive electron (not act a thing)
- they too have moderate penetrating power

Question 19

gamma rays

Answer 19

0
y
0
- electromagnetic radiation
- (no mass, no charge), just energy
- have the greatest penetrating power, they can be stopped by a sheet of lead

Question 20

alpha decay

Answer 20

the emission of alpha particles (helium atom)
- reduces the atomic number by 2 and reduces mass # by 4

Question 21

total mass and charge on the reactant side must equal

Answer 21

total mass and charge on the product side

Question 22

beta decay

Answer 22

• the emission of beta particle (like an electron)
• will result in NO change in the mass # but the atomic # will increase by 1

Question 23

positron decay

Answer 23

the release of a positron
- mass number stays same
- atomic #/nuclear charge decreases by 1

Question 24

gamma radiation

Answer 24

high energy electromagnetic radiation
- no change in mass or atomic number
- only a reduction in energy
- not a transmutation bc the proton number is not affected, only a loss of energy

Question 25

how dyk its a natural transmutation

Answer 25

- the equations ALL have ONE REACTANT on the left hand side!!

Question 26

artificial transmutation equations

Answer 26

- two reactants, not happening naturally - something has HIT the unstable nucleus and caused it to break down - happens in nature or caused by scientists in lab

Question 27

half life

Answer 27

the TIME it takes for ONE HALF of the nuclei in a sample to decay - not affected by temp or pressure

Question 28

nuclear reactions

Answer 28

small amount of mass is converted into large amounts of energy

Question 29

fission

Answer 29

the splitting of a heavy nucleus to produce a lighter nucleus

Question 30

fusion

Answer 30

involves the combining of light nuclei to produce a heavier nucleus

Question 31

fission reaction

Answer 31

- slow moving neutron bombards a heavy element (ex: U or Pu) - results in an unstable nucleus which splits (undergoes fission) - large amounts of energy released

Question 32

what are fission reaction used for

Answer 32

- to generate nuclear power (electricity) - to produce nuclear weapons **technically total mass of reactants does not equal total mass of products bc mass was used to create energy

Question 33

fusion reaction

Answer 33

- light nuclei fuse/join to form a heavier nucleus - high temperature and pressure is needed ex: energy produced from sun and stars, produced by hydrogen bomb

Question 34

nuclear reactors

Answer 34

- are devices for controlling nuclear reactions so that energy released by the reaction can be converted to a useful form at a constant rate

Question 35

fission reactors

Answer 35

- produce energy (ex: electrical energy) from the fission of U-235 - parts: used currently in nuclear plants - fuel: uranium-235 **expensive, dangerous

Question 36

fission reactor: moderator

Answer 36

slows down neutrons so that they can be captured by U-235 (ex: Graphite)

Question 37

fission reactor: control rods

Answer 37

control the supply of neutrons

Question 38

fission reactor: coolant

Answer 38

heavy H2O (deuterium), air, He, or CO2

Question 39

fission reactor: shield

Answer 39

covers reactor, protects from radiation

Question 40

fusion reactors

Answer 40

- for the future - same parts of a fission reactor - requires extreme temperatures (10^9)°C - runs on inexpensive fuel (*deuterium) - clean process: isotopes are stable as opposed to radioactive isotopes made in fission reactions

Question 41

benefits of radioisotopes

Answer 41

- radioactive dating - chemical tracers - food preservation

Question 42

benefits of radioisotopes: radioactive dating

Answer 42

- uses the ratio of C-12/C-14 to date previously living things - U-238/Pb-206 to date geological material (earth age, rocks)

Question 43

benefits of radioisotopes: chemical tracers

Answer 43

- the ability to detect or trace radioactive materials ex: I-131 detects and helps treat thyroid conditions ex: Tc-99 and Co-60 treats cancer bc they emit gamma rays ex: C-14 helps in the study of photosynthesis

Question 44

benefits of radioisotopes: food preservation

Answer 44

Co-60 and Cs-137 are being used to kill bacteria in foods

Question 45

disadvantages of radioisotopes

Answer 45

● Radioisotopes can kill healthy tissue as well as cancerous cells ● Radiation can lead to mutations that can be inherited ● It is difficult to store fuel and dispose of wastes at a nuclear power plant - Radioactive substances contaminate their surroundings for generations, depending on their half life Ex. 137 90 Cs or Sr 55 38