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 = 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?
- 1 to 10 degrees: 85 particles, the biggest row that the model forbids outright
- Over 90 degrees: 3 particles turned back, which no spread-out charge can do
- 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?
- It is spread through the whole atom, but unevenly, with three thick spots in it
- Almost all of it sits in a region so small that particles rarely come close
- Most atoms have no positive charge, so only 3 particles ever met any of it
In Rutherford's model, one close pass by a nucleus causes a large turn. If the foil were twice as thick, how many particles would turn over 90 degrees, Luz?
- The same number, since the size of a single nucleus does not change with the foil
- Zero, since the thicker foil would stop the particles before they could turn back
- About twice as many, since there would be about twice as many nuclei to meet
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 lighter than a hydrogen atom
- Its particles are about 1,800 times heavier 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?
- Neither broke, since electrons are too small to count as parts
- Both broke, since atoms have parts, so ratios of whole atoms mean nothing
- 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?
- 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
- Bend a beam in a magnetic field and measure its charge-to-mass ratio again
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 Rutherford's model is worthless and should be discarded
- Four colors appear, so hydrogen must have exactly four electrons
- Only four colors appear, so the electron's energy must change in set steps
Bohr's model allows 656, 486, 434 and 410 nm in hydrogen but nothing near 600 nm. Which result would count against it, Tala?
- A bright hydrogen line at 656 nm, the red line the model predicts
- A bright hydrogen line at 600 nm, which no allowed drop produces
- Hydrogen's lines looking dimmer when the lamp runs at lower power