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1: Pyruvic acid: C3H4O3.
Dalton had no idea about the shape of the molecules of course. The only thing he was able to measure was the ratio between the particles and think of something nice and symmetrical.
2: He though there was an atmosphere of heat surrounding the particles. Molecules of ice had less of this atmosphere.
3: He was able to use the ratios in which the compounds reacted to calculate the ratios in which certain particles should be present in a molecule.
4:
5: Bromine, Iodine, Nitrogen, Chlorine, Hydrogen and Fluorine. (remember: BrINClHOF)
6: The synthesis of ozone from oxygen. Since Dalton never thought that any “atom” could form a compound with the same particle, he would have never thought of turning 3 O2 into 2 O3.
7:
8: Clearly Berzelius.
9: He didn’t make the mistake Dalton made and he recognised that two atoms of the same kind could form compounds. The technology to measure was also improved.
10: He though the particles were positive and negative so the attracted each other.
11A: 11,016 u
11B: 44,01 u
11C: 32 u
11D: 16,042 u
11E: 80,06 u
11F: 267,336 u
12: He though the atom was like a pudding with electrons floating around in is like plums. The Dutch “Krentenbolmodel” fits the description too.
13:
14: In this model, the atom was no longer an indivisible sphere, it could be “broken” by removing the electrons.
15: They’re still spheres.
16: The ability to take a photograph of the electron.
17:
18: In his experiment, some particles were reflected back but most of them would go straight ahead. To make the particle bounce back, the mass had to be sufficient and since most of the particles went straight through, that mass needed to be concentrated in a small place.
19: The atom is mostly empty in Rutherford’s model, Thomson’s model had a full and substantial atom.
20: He expected that the atoms in the gold foil would either allow all particles to pass or to absorb all particles:
What he saw was:
21: In Bohr’s model, the electrons were orbiting the nucleus at several specific distances. Rutherford also thought they were orbiting the nucleus but all at the same distance.
22: You need more energy in a photon of visible light than in IR. You cannot “make” energy.
23: You want to see the light coming off the materials but not the light that is going to those materials. With UV fluorescence, the light from your lamp is nice and invisible while the light coming from the materials is not. In fluorescence from blue to yellow, there would be yellow light coming from the materials but it would be hard to see in the blue light from your lamp.
24:
25: 2,8,2
26: In Bohr’s model, the electrons were orbiting the nucleus at a few distinct distances. Rutherford also thought they were orbiting the nucleus but all at the same distance.
27: Their argument was a good one. Their view was based on actual experiments and at that moment, no measurements or observations conflicted with that theory. If Bohr hadn’t been able to explain some experiments better than the chemists could, the world would have been right to believe the chemists.
28: Chadwick
29: The nuclear electron would reside in the nucleus and not in orbit around it.
30: They used a magnetic field. A charged particle creates its own magnetic field when it moves, that’s why moving electrons in a coil turn the coil in an electromagnet. Because the moving particles did not respond to an external magnetic field, Bothe and Becker concluded that those particles did not create their own magnetic field and that can only happen is the particles were neutral.
31: Gamma radiation is light, photons have no mass.
32: Einstein did not like the uncertainty of quantum mechanics. He believed that all things were known or knowable. Quantum mechanics introduced the fact that some properties of particles are actually undetermined, "not even god could say what the property is".
33: The uncertainty in the velocity of the proton or neutron is just ≈5,37.106 m/s. Well under the speed of light so they don’t violate Einstein’s law.
34: Nucleus
35: positive
36: neutral
37: negative
38A: Neutron
38B: Proton
38C: Electron
39: The rule: The amount of protons determines what element a certain atom is.
40: A neutral atom (no charge) has the same amount of protons as electrons
41: A positive ion (positive charge) has more protons than electrons
42: A negative ion (negative charge) has more electrons than protons
43: So, to calculate the charge you need to: Subtract the amount of electrons from the amount of protons
44:
45: The mass number is the amount of protons plus the amount of neutrons
46: The electrons have no effect on the mass number.
47:
48:
49:
50: No, you wouldn’t.
51: There is no definitive rule. In the lower atomic numbers, the amount of protons and neutrons should be about the same but you can’t say that for certain. Hydrogen and Helium are stable when you have the same amount of neutrons as protons or one less neutron, Lithium want the same amount or one more neutron, of Beryllium, there is only one composition stable.
52: A particle of 2 protons and 2 neutrons
53: Electrons
54: Light (photons)
55: Because electrons have a negative charge
56: Alfa or beta
57: Alpha
58: The particle can’t ionise the air very well
59: The particles won’t travel far enough to reach the scanner
60: Almost all of the radiation would go through, you would not detect a difference when you have a different thickness of paper.
61: The grey uses the amount of energy the particle imparts on the tissue, it doesn’t matter which particle that was.
62: 2,6.105 grey
63: 46,43 kg
64: Beta
65: Gamma
66: a smoke detector used to.
67: Gamma
68: The cells that receive it might become cancerous
69: The cells die and since their neighbours die as well, they can’t be replaced. The organ might stop functioning
70: to turn into an ion
71: The alpha particles can’t reach far through air
72: Everywhere
73: Because the body will automatically transport it to the thyroid.
74: They don’t have a prostate.
75: So the patient doesn’t remain radioactive for long.
76: The gamma rays are likely to pass through the gas without ionising a single atom.
77: All the ions have become atoms again, they’re not attracted to the sides anymore and are ready to be ionised again.
78:
79: 6 days
80: 6 days
81: 6 days
82: 6 days (this makes typing an answer sheet very easy)
83: Your amount of dice was limited so it might differ a bit but with a calculation, you would get 1,7095 seconds (rolls).
84: Uranium-238 and Carbon-14
85: Only the things that breath in carbon from the atmosphere and use that carbon to build themselves (plants), things that eat the carbon from plants and use it to build themselves or things that eat the previous things can have carbon from the atmosphere in them. Anything that lives does this but things that have never lived don’t. You cannot carbon-date a thing that hasn’t lived.
86: See whether it has lived.
87: The tree is still replenishing its amount of carbon-14. The measurement will always be 100%.
88: No. The decay of carbon-14 is far too slow. It would take 8,27 year for the amount of Carbon-14 to drop by 0,1 percent.
89:
90: 25% means that the activity has halved twice: 2.5730=11460 years
91: 96/19,2=5. 5 half-lives have passed: 250 000.(0,5)5=781,25 Bq
92: 10/2,5=4. Four half-lives have passed: 50 000 000.(0,5)5=3125000 atoms.
93: 60 000/7500=8. Eight half-lives need to have passed. The half-live is 180 year so 8.180=1440 year.
94: The half-life is 8 days. 40/8=5 so 5 half-lives have passed. 5000.(0,5)5=156,25 Bq.
95: A neutron is shot into it.
96: The neutron carried a lot of kinetic energy, that energy is now part of the nucleus and that makes it unstable.
97: Unstable means either an isotope that has too many or too few neutrons or it has too much energy.
98: When a Uranium-235 nucleus is hit with a fast neutron, it explodes into two new nuclei, three (or two) new fast neutrons and a lot of energy. Each of these three neutrons is able to trigger a fission in another nucleus, releasing 9 neutrons, then 27, then 81, then 243, 729, 2187, 6561, 19683 etc.
The amount of Uranium-235 in close proximity affects the reaction speed. If neutrons are able to escape or are caught without triggering another fission, the amount of fissions will decrease and the reaction will slow down.
99: One of the reaction products in the ingredient for the next reaction.
100: They catch the neutrons. If they catch 66% of all neutrons, each reaction can only trigger one other reaction. This means the total amount of reactions per second stays the same. If they catch more, the amount of reactions decreases.
101:
102: No. None of the reaction products are necessary for the next reaction. A chain reaction is impossible.
103: A fission reactor has to slow down the reactions, a fusion reaction has to force the reactions to occur.
104: Helium
105:
Costs = €4400+€900+25*€150+5*2*€35=€9400
Benefits = 25*€550=€13750
Profit= €13750-9400=€4350
So yes, it is profitable.
106:
Initial investment = €4400
Profit per year = €550-€150-€900/25-€350/25=€350
Payback period = €4400/€350 = 12,57 years
Since the panels will last 25 years, it is profitable to invest.
107:
108A: Fossil fuels have a lot of energy per litre/kilogram and are quite easy to mine. There is just a finite amount, combustion leads to CO2 and several harmful chemicals in the atmosphere.
108B: Nuclear power (fission) has an insane amount of energy per kilogram and no exhaust fumes like CO2. The amount of fissile fuel is also finite and the nuclear waste stays dangerous for decades and centuries.
108C: The energy from the sun is renewable and literally free and no exhaust fumes or waste. The solar panels need a lot of surface area to produce enough electricity and the panels last only for so long. On overcast days, the production is less.
108D: The energy from the wind is renewable and free as well, there are no exhaust fumes and each turbine produces quite a bit of electricity. The wind mills are large and not very pretty, a lot of people don’t want their view spoiled and bird can get hit. The wind mills are mechanical and can break down. On windless days, there is no production at all and on stormy days, the windmills need to be shut down to avoid damaging them.
109 and 110: Discuss with your teacher whether your answers are correct.
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