Answer: Bohr postulated that electronic energy levels are quantized. Secondly, a photon of light of a particular frequency is emitted when electrons move from a higher to a lower energy levels.
Explanation:
The Bohr model of the atom is the immediate predecessor of the wave mechanical model of the atom. The wave mechanical model refined the Bohr's model by treating the electron as a wave having a wave function psi. The wave function describes the identity of the electron. From Heisenberg uncertainty principle, the position of a particle cannot be accurately and precisely measured. Hence the wave mechanical model added that electrons are not localized in orbits according to Bohr's model but the integral of psi squared dx gives the probability of finding the electron within a given space.
The first reason to repeat experiments is simply to verify results. Different science disciplines have different criteria for determining what good results are. Biological assays, for example must be done in at least triplicate to generate acceptable data. Science is built on the assumption that published experimental protocols are repeatable.
2) The next reason to repeat experiments is to develop skills necessary to extend established methods and develop new experiments. “Practice make perfect” is true for the concert hall and the chemical laboratory.
3) Refining experimental observations is another reason to repeat. Maybe you did not follow the progress of the reaction like you should have.
4) Another reason to repeat experiments is to study and/or improve them in way. In the synthetic chemistry laboratory, for example, there is always a desire to improve the yield of a synthetic step. Will certain changes in the experimental conditions lead to a better yield? The only way to find out is to try it! The scientific method informs us that it is best to only make one change at a time.
5) The final reason to repeat an extraction, chromatographic or synthetic protocol is to produce more of your target substance. This is sometimes referred to scale-up.
Answer:
B. Nickel Chloride
Explanation:
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Answer:
209.68
Explanation:
The only number that is relevant (though the rest are quite interesting) is the last one 1.98 * 10^24
1 mole of Barium Acetate Contains 6.02*10^23 particles.
There are 4 moles of carbon to every mole of Barium Acetate.
1.98 * 10^24 atoms / (4*6.02*10^23)
0.8223 moles of Ba(C2H3O2)2
Ba = 137
4C = 4*12 48
6H = 6*1 6
4O = 4*16 64
1mole 255 grams
0.8223 * 255 = 209.68 grams
I have used rounded masses for these elements depending on the periodic table you use. Go through the question with your masses to get a more accurate answer. My answer will not differ by much. It is a guide.
The study of the elements and forms of matter.
