How the model of the atom changed
Grade 10 Science Worksheet
Circle the best answer, or write your answer on the line.
In Bohr's hydrogen model, level n has E = −13.6 ÷ n² eV. An electron drops from n = 4 to n = 2. What energy does its photon carry, to 0.01 eV, Ari?
In Bohr's hydrogen model, level n has E = −13.6 ÷ n² eV. An electron drops from n = 5 to n = 2. What energy does its photon carry, to 0.01 eV, Bo?
In Bohr's hydrogen model, level n has E = −13.6 ÷ n² eV. An electron drops from n = 6 to n = 2. What energy does its photon carry, to 0.01 eV, Esme?
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Alpha particles on gold foil (example data)
turn angle particles under 1 degree 19,901 1 to 10 degrees 85 10 to 90 degrees 11 over 90 degrees 3 Thomson's model allows only tiny bends, under 1 degree. Which row is the strongest evidence against it, Jun?
- Over 90 degrees: 3 particles turned back, which no spread-out charge can do
- 1 to 10 degrees: 85 particles, the biggest row that the model forbids outright
- Under 1 degree: 19,901 particles, far more than any other row, so they matter most
Three of 20,000 particles turned over 90 degrees. What does that say about the positive charge, Kira?
- Most atoms have no positive charge, so only 3 particles ever met any of it
- Almost all of it sits in a region so small that particles rarely come close
- It is spread through the whole atom, but unevenly, with three thick spots in it
The beam's charge-to-mass ratio is about 1,800 times a hydrogen ion's (modern value). If its charge matches the ion's, what does that mean, Milo?
- Its particles are about 1,800 times heavier than a hydrogen atom
- Its particles are about 1,800 times lighter than a hydrogen atom
- Its particles have the same mass as hydrogen but 1,800 times the charge
The 1897 beam showed atoms contain electrons. Which of Dalton's claims did that break, and which survived, Noah?
- Both broke, since atoms have parts, so ratios of whole atoms mean nothing
- Neither broke, since electrons are too small to count as parts
- Indivisible atoms broke; atoms joining in whole-number ratios survived
Thomson's and Rutherford's atoms both hold electrons and are neutral. Which test could tell the two models apart, Pia?
- Bend a beam in a magnetic field and measure its charge-to-mass ratio again
- Weigh a gold sample before and after heating it in an open dish
- Fire fast alpha particles at thin gold foil and count the large turns
Hydrogen's visible lines (real data, rounded)
color wavelength (nm) red 656 blue-green 486 blue-violet 434 violet 410 Rutherford's atom predicts light of every color. How does the table challenge it, Ren?
- Four colors appear, so hydrogen must have exactly four electrons
- Four colors appear, so Rutherford's model is worthless and should be discarded
- Only four colors appear, so the electron's energy must change in set steps
What each model explained (summary of the sheet)
model explained could not explain Dalton 1808 masses combine in whole-number ratios electrons from atoms Thomson 1904 electrons in neutral atoms particles bouncing back from foil Rutherford 1911 particles bouncing back from foil hydrogen's few colors Bohr 1913 hydrogen's few colors helium's colors Zee reads the table. Which statement about the four models is best supported?
- Each model explained its day's evidence and failed on newer evidence
- Each model failed because its inventor ignored the evidence of the day
- Each new model threw out everything its predecessor explained
