Chemistry Unit 5
What was Einstein's formula?
-E=mc^2 -energy =s (mass/matter)(speed of light)
What will occur to the atomic number and the mass number of the daughter nucleus in alpha decay?
-the atomic number goes down by 2 (lost 2 protons) -mass number goes down by 4 (lost two neutrons and 2 protons)
What are the two types of Artificial Transmutation:
1- If a charged particle collided with the nucleus (can be alpha or proton- small positive particle) 2-If a neutron (uncharged) collides with the nucleus
5 characteristics of nuclear reactions:
1- atoms achieve stability by changing nuclei (emit particles and rays) 2- atoms of 1 element are converted to atoms of another element 3- nuclei reactions always involve protons and neutrons 4- they always involve a large energy change 5-the rate of a reaction never changes
3 ways radioisotopes are used in medical applications:
1- cancer therapy 2- contrast 3- to irradiate food
What two things are learned from Einstein's formula?
1- energy and matter can be converted 2- a tiny bit of matter converts to a much larger bit of energy
When are chemical tracers used? (2 ex)
1- fertilizer0 where does it end up (stem, root, or leaf) 2- how co2 ended up as sugar-carbon cycle (explained in notes)
When can a fission chain reaction be used? (2)
1- nuclear power plant 2- nuclear bomb
Advantages of Nuclear Energy: (2)
1- produces lots of energy really fast 2- clean energy (no pollution/global warming)
Disadvantages of Nuclear Energy: (2)
1- radioactive waste- midsize nuclei themselves are radioactive and can't be thrown out 2- potential nuclear accident
Why is fusion better than fission? (2)
1- the products are stable (no radioactive waste) (tots clean) 2- more energy than fission
What is so dangerous about radioactive waste? (2)
1- they have long half-lives, so emit radiation for a long time 2-can't be thrown out
3 types of Natural Radiation:
1-alpha decay 2-beta decay 3-gamma radiation
-How to stop a fission chain reaction? (2) -How is this utilized in a nuclear power plant?
1-neutron absorbers (remove them from system) 2-neutron moderators- slow down neutrons -rods are put in reactors to absorb and slow down the neutrons
4 ways radioisotopes are utilized:
1-radioactive dating 2-Industrial application 3-Chemical Tracers 4-Medical Applications
What is the rate of a reaction unaffected by? (4)
1-temperature 2-pressure 3-concentration 4- presence of a catalyst
When a radioisotope is bigger which ratio line is it closer to?
1.5 than 1:1
If there is a low atomic number (below 20) what will the ratio be between protons and neutrons
1:1
If there is an atomic number above 20 with medium nuclei size what will the ratio of the nucleons be?
1:5
What is the speed of light?
3*10^8 m/c
How much energy is released in fusion?
5 *10^8 kj/g
How does beta decay occur? What does it release?
A neutron can break down to form positive part with all the mass (proton) and negative part with no mass (beta particle)
PP of all natural radiations from lowest to highest:
Alpha, beta, gamma
Why is the mass, charge, attraction and Penetrating Power of gamma rays the way they are?
Because gamma rays aren't particles they have no mass and charge and because they have no charge they aren't attracted to anything. Since they have no mass they have the strongest penetrating power of all radiations.
Where does the energy in fusion and fission come from?
Binding energy
Charge, Mass, Attraction, and Penetrating Power of an Alpha Particle
Charge= +2 Mass= 4 amu (2p+2n) Attraction= to negative area (because of positive charge) PP=Low
Which radioisotopes irradiate food? What does that do? (ex)
Cs-137 and Co-60- it gets rid of bacteria (spices, dried fruit, etc.,)
How is matter converted to energy?
Einstein's formula
Who was the first person to do artificial transmutation? When? What did he do?
Ernest Rutherford in 1919. He converted 1 element to another by shooting alpha particles (helium) at nitrogen atom and converted it to an unstable fluorine atom
What is an alpha particle?
Helium nucleus with 2 protons and 2 neutrons
How does C-14 dating work?
In the atmosphere, N-14 turns into C-14 by cosmic radiation. C-14 interacts with environment so that the ratio of of stable isotope (c-14 and c-13) in the body is the same ratio as the environment. But, when the organism dies it stops exchanging carbon and the stable isotopes remain while the unstable ones decay. The ratio of the unstable carbon in the fossil is compared to atmospheric ratio to measure how long ago the organism died.
Which radioisotopes are used to diagnose thyroid disorders? How does it work?
Iodine-131- it sees if thyroid absorbs iodine which produces thyroxin. The person drinks the solution and is scanned to see how much of the hormone was absorbed.
What rule the mass defect indicate?
Law of Conservation of Matter and Energy
What will occur to the atomic number and mass of a daughter nucleus in a positron emission?
Mass will stay the same and the atomic number will decrease by 1
Mass, Charge, Attraction, and Penetrating Power of a Positron:
Mass= 0 Charge= +1 Attraction= to negative area PP= medium
Mass, Charge, Attraction, and Penetrating Power of Gamma Rays:
Mass= 0 Charge=0 Attraction= neither + not - areas PP=very strong
Nuclear Chemistry
Study of the nucleus and its reactions
What radioisotope detects brain tumors?
Tc-99m
What is a problem with carbon dating?
That it's assumed the ratio today of C-14 is the same as today
Where does the binding energy come from?
The mass defect- the missing mass that occurs when two nucleons are put together and is converted to binding energy to pull them together
If someone wants to find out the age of an object that never lived what isotope is used?
Uranium-238 which decays to form the stable isotope of Pb-206
What is positron emission?
When a nucleus gives off a positive electron (no mass but positive charge)
What occurs in fission?
a heavy nucleus is shot at with a neutron and it usually forms a very unstable isotope which immediately splits into 2 more lightweight nuclei and gives off 2 to 3 neutrons and a lot of energy
What does fission cause? What is it?
a nuclear chain reaction- a reaction gives off neutrons which are shot at a heavy nucleus which make more neutron s which are shot at a heavy nucleus which creates more neutrons which are.....
How does a positron emission occur?
a protons breaks up to form a particle with all the mass and no charge and a particle with no mass and all the charge
What is the procedure in a fission reaction?
a small particle (neutron) is shot at a heavy, unstable nucleus
Mass of all natural radiations from highest to lowest:
alpha particle, beta particle, gamma ray
Charge of all natural radiations from highest to lowest:
alpha, beta, gamma
What are the penetrations of alpha radiation, beta, and gamma halted by (what can they go through)?
alpha=stopped by paper beta= few inches into skin gamma=can go through skin and water stopped by few cm of concrete
What symbol is given to the radioactive isotope? Why?
an "m" to show that its the reactant
In a gamma radiation equation what symbol is the unstable isotope given? Why?
an asterisk to show its unstable form
What happens in beta decay?
an unstable nucleus releases beta particle
Define alpha decay
an unstable nucleus which releases an alpha particle
Two types of transmutation
artificial and natural
What kind of nuclear reaction is fission?
artificial transmutation
Why is the penetrating power of an alpha particle low?
because its massive and can't get through a lot of things
Why is mass conserved in Beta Decay?
because the negative particle turned into a positive particle (P to N)
Why do nuclear reactions deal with so much energy?
because the tiny matter that is lost is converted into huge energy
Which size of nuclei are usually unstable?
big and heavy
What kind of nuclei are alpha emitters?
big heavy nuclei
What size can a beta emitter be?
big or small
Which element has the shortest half-life?
calcium
Why isn't fusion used in power plants?
can't get the temperature and pressure needed for the reaction to occur- the minimum temperature needed is 40 million degrees celsius
Which is the most common isotope used in radioactive dating?
carbon-14
Which radioisotopes are used in cancer therapy?
cobalt-60 and Pa-226 emit gamma radiation at tumor cells in order to kill the cancer cells
What chemistry rule applies in alpha decay?
conservation of mass and charge
What law applies to Beta Decay?
conservation of mass and charge
What is the product in the alpha decay equations?
daughter nucleus and alpha particle
What is the mass of an electron, proton, and neutron?
e= almsot zero p= 1 n=1
What is a beta particle?
electron from nucleus
When is U-238 used?
geological formations (rocks, earth, etc.,)
What is needed for a fusion reaction? Why?
high temperature and pressure because combining two nuclei
If too much thyroxin is absorbed what's it called?
hyperthyroidism
If too little thyroxin is absorbed what's it called?
hypothyroidism
How can you tell the difference between an equation depicting natural or artificial transmutation?
in natural there is only one reaction whereas in artificial there is 2
What happens when a nucleus is unstable?
it decays naturally into a more stable nucleus
What is a property of the rate of decay?
it is independent of variables- can't speed up or slow down
Why is radiation dangerous?
it is mutagenic and if it reaches cells (can happen with gamma) it causes the ionization of molecules (they become charged) in the cells and they can't perform their functions and they die. If the ionization reaches the DNA it mutates it and causes faulty programming. If it reaches the DNA on an egg or sperm cell the mutation becomes hereditary.
What is a gamma ray? What kind of radiation does it have?
it is not a particle but has very high radiation
How is artificial different than natural?
it occurs by being bombarded vs. spontaneously decomposing
How does gamma radiation stabilize a nucleus? What does this do to the equation?
it releases a lot of energy and as a result it rearranges the protons and neutrons in a nucleus. Nothing left nucleus but was rearranged so the mass and atomic numbers stay the same.
What does alpha decay release? What does it form?
it releases and alpha particle and forms the daughter particle
What happened to Rutherford's fluorine atom?
it spontaneously decomposed to form o-17 and gave off a proton
Mass, Charge, Attraction, and Penetrating Power of Beta Emitter
mass=zero charge=-1 attraction= positive area PP= medium
Example of natural transmutation
naturally changes from carbon to nitrogen
What is the particle with all the mass and no charge?
neutron
What isn't always produced in a fusion reaction?
neutrons
What can you predict of decay in a given sample?
not which atoms will decay but that approximately 50% will- the average
Define radiation
particles or energy/rays that are emitted during decay
What are transuranium elements?
past uranium unnatural and artificially created by artificial transmutation
What is the particle with no mass and all the charge?
positron/ positive electron
What is decay governed by?
probability- it is totally random
Define radioactivity
process through which particles release radiation
What is/are the thing/things after the arrow in the nuclear equations?
products
What is inside the nucleus?
protons and neutrons
What need to maintain an ideal stable ratio to stabilize the nucleus?
protons and nuetrons
Define Gamma Radiation
radioisotopes emit gamma rays
Define Half-life
rate of radioactive decay- the amount of time required for half the atoms in a given sample to decay
What is the thing before the arrow in the nuclear equations?
reactant
Transmutation
reaction that changes the nucleus of one element to another
Which type of artificial transmutation is easier? Why? (2)
sending a neutron: 1) it doesn't have to be sent at extremely high speeds because it isn't repelled by the positive nucleus 2) they are often products of other nuclear reactions and are available to be bombarded with
What energy occurs from a fusion reaction?
solar energy
What is a chemical tracer?
something that follows the path of a material through a system
What is another term for fission?
splitting
In the Band of Stability what does each dot represent?
stable isotope
What is the reactant in the alpha decay equations?
the alpha emitter
What is the use of one biproduct of fission?
the neutrons can be used to shoot at other nuclei
Why does the atomic number change in a positron emission?
the neutrons went up by 1 and the protons went down by 1 (the proton turned into a neutron)
What is the atomic number?
the number of protons/electrons in an element's nucleus
What is the activity (y axis) in a half-life graph?
the number of radioisotopes remaining (how much radiation was emitted)
What is binding energy?
the strong nuclear force holding the nucleus together even though it is repelled by the protons
Where does fusion occur?
the sun
Why don't the protons in a nucleus constantly repel each other and destabilize the nucleus?
there is a strong binding force/energy keeping the nuclei together
What happens to the mass number and the atomic number of a daughter nucleus in gamma radiation? Why?
they stay the same as the radioisotope because the gamma emitter doesn't lose particles
What does C-14 work with?
things that were once living
When is artificial transmutation used?
to decompose the transuranium elements
What is a half-life graph used for?
to determine the half life of a radioisotope
Which two situations use contrast?
to diagnose a thyroid disorder and detect brain tumors
Define radioactive dating
to measure the amount of radioisotope to determine the age of an object
Why must an alpha particle or a proton must be moving at high speed to conduct Artificial Transmutation?
to overcome the repulsion by the positive nucleus
What is The Band of Stability useful for?
to plot all the stable nuclei with ratio of protons to neutrons
How are radioisotopes used in Industries?
to recognize different radiation have different penetrating powers/ to see how strong something is/ what radiation can go through it/ material strength=penetrating power
What else are neutrons in artificial transmutation used for?
to repair the radioactive nuclei in which the products often decay
What is above the Line of Stability? What does that result in?
too many neutron so decay the neutrons to increase the protons
What is below the Line of Stability? What does that result in in a nucleus?
too many protons which results in the decay of protons to increase neutrons
What is the mass number?
total amount of protons and neutrons in a nucleus
What are fission and fusion?
two types of artificial transmutation that release a lot of energy
What ideal radioisotopes are used in medical applications?
unstable ones with short half-lives so decay quickly and shorten the body's exposure to radiation
Which element has the longest half-life?
uranium
What are variations of artificial transmutation based on?
what is sent at the nucleus
What is a daughter particle?
what resulted from the decay
What indicates penetrating power?
what the radiation can go through
What is a Fission Reaction?
when a heavy nucleus is split into lighter nuclei
Define Artificial Transmutation:
when a nucleus is bombarded with high energy particles to change it into a different element
What is the mass defect
when the mass of all the nucleons are added together the mass is slightly bigger than the mass of the nucleus containing the nucleons
What is a fusion reaction?
when two lightweight nuclei are combined to form one heavy nucleus
What is artificial transmutation
when you cause it to change
What does stability of nuclei indicate?
why natural transmutation would occur (why would it change from carbon to nitrogen?)
How can nuclei affect stability?
Protons are all positive so if there are a lot of them in the nucleus they will repel each other and the nucleus won't be stable
What happens to the mass and atomic number of a daughter nucleus in beta decay?
Same mass and the atomic number increases by 1 (lose negative particle)
Whats keeps the nuclei stable?
The neutrons with no charge which balance out the positive charges of protons
If there is an atomic number above 83 what occurs?
The positive charge of the protons is too much to handle and it results in an unstable nucleus
