How the model of the atom changed
Grade 10 Science Worksheet - Challenge Me
Circle the best answer, or write your answer on the line.
A hydrogen electron drops from n = 3 to n = 2 (rules on the sheet note). What wavelength does its photon have, to the nearest nm, Ari?
A hydrogen electron drops from n = 4 to n = 1 (rules on the sheet note). What wavelength does its photon have, to the nearest nm, Bo?
A hydrogen electron drops from n = 7 to n = 2 (rules on the sheet note). What wavelength does its photon have, to the nearest nm, Esme?
Read this first
Hydrogen's energy levels in Bohr's model (from E = −13.6 ÷ n²)
level n energy (eV) 1 −13.60 2 −3.40 3 −1.51 4 −0.85 A hydrogen atom in level 1 meets photons of 10.2 eV and 11.0 eV (levels on the card). Which does Bohr's model absorb, Kira?
- Both, since each photon carries at least the 10.2 eV that the jump needs
- Only the 10.2 eV photon, which lifts the electron exactly from n = 1 to n = 2
- Neither, since lifting an electron up always needs the full 13.6 eV of ionization
A student writes: Rutherford proved electrons orbit the nucleus like planets. Using the gold-foil results, what is the best verdict, Milo?
- Supported: a nucleus at the center means electrons must circle it like planets
- Not supported: foil results locate the positive charge but not how electrons move
- Supported: the large turns were caused by orbiting electrons pulling on the particles
A student says: Dalton's model was replaced, so none of it is still used. Which reply is best supported, Noah?
- Right: once a model is replaced, each of its ideas is discarded with it
- Overstated: whole-number ratios of atoms and rearranged atoms in reactions still hold
- Right, since Dalton knew nothing about electrons or the nucleus when he wrote it
Only 1 in 8,000 particles bounced back. In a short test of 800 particles, none did. Pia says that refutes the rate. What is the best reply?
- No: at 1 in 8,000, 800 particles give about 0.1 bounces, so none is expected
- Yes: the rate predicts about 1 bounce in 800, and none appeared in the test
- Yes: only a test of 8,000 or more particles can ever check a rate like this
A gold atom is about 3 × 10⁻¹⁰ m wide and its nucleus about 1.4 × 10⁻¹⁴ m (rounded). If the nucleus were a 1.4 cm marble, how wide would the atom be, Ren?
- About 300 m
- About 3,000 m
- About 30 m
Which model explains which observation (summary of the sheet)
observation Dalton Thomson Rutherford Bohr compounds form in whole-number ratios yes yes yes yes electrons come out of atoms no yes yes yes particles bounce back from foil no no yes yes hydrogen gives only a few colors no no no yes helium gives its own pattern of colors no no no no Tala reads the table. Which statement does it support?
- Bohr's model explains every row in the table, including the helium row
- Each model explained every row its predecessor did; none explains helium's colors
- Thomson's model explains why alpha particles bounce back from the gold foil
Card
Thomson's model (example numbers). Each atom bends an alpha particle by at most 0.01 degrees, in a random direction. Random bends add like the square root of their count. The foil is 1,000 atoms thick.
Using the card, which argument shows Thomson's model cannot give a 90 degree turn, Zee?
- Even with all 1,000 bends in line, the total is 10 degrees; random ones give 0.3
- Random bends cancel completely, so the total would be exactly zero, not 90 degrees
- 1,000 bends of 0.01 degrees easily add to 100 degrees, enough for a 90 degree turn