How the model of the atom changed
Grade 10 Science Worksheet - Building Confidence
Circle the best answer, or write your answer on the line.
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 An electron in hydrogen drops from level n = 3 to n = 2 and gives off one photon carrying the energy it lost. How much energy does the photon carry, to 0.01 eV, Ari?
An electron in hydrogen drops from level n = 4 to n = 3 and gives off one photon carrying the energy it lost. How much energy does the photon carry, to 0.01 eV, Esme?
Card
Atom models and the evidence behind them. 1808, Dalton: atoms are solid, indivisible spheres. 1897, evidence: a beam in a vacuum tube bends toward a positive plate, so it carries negative particles (electrons) that come out of atoms. 1904, Thomson: a positive sphere with electrons dotted through it. 1909 to 1911, evidence: in a gold-foil test, most alpha particles pass straight through and a very few bounce back. 1911, Rutherford: a tiny, dense, positive nucleus with electrons around it. 1913, evidence: hydrogen gas gives off light of only a few colors. 1913, Bohr: electrons on set energy levels.
Jun reads the card. Which change to the atom model came right after the 1897 beam-bending evidence?
- Electrons were placed inside atoms, which were no longer indivisible
- A tiny, dense nucleus was added at the center of the atom
- Electrons were given set energy levels around the nucleus
Kira reads the card. Which change to the atom model did the gold-foil evidence force?
- Electrons were added to the atom for the first time, inside a positive sphere
- Electrons were put on set energy levels instead of dotted through the atom
- Positive charge moved from a spread-out sphere into a tiny, dense nucleus
Dalton called atoms indivisible. Luz reads the card. Which evidence first contradicted that?
- The gold-foil test, because particles bounced back from atoms
- The hydrogen light of 1913, because the colors were few
- The 1897 beam, because electrons came out of atoms
Thomson made his beam in tubes with different gases and cathodes of different metals. The beam was always the same. What did that suggest, Milo?
- Only the gas in the tube contains electrons
- Each gas makes its own kind of electron
- Electrons are a part of every kind of atom
In a described run (example data), 7,999 of 8,000 alpha particles pass nearly straight through foil and 1 bounces back. What does that say about the positive charge, Noah?
- It is spread evenly, but the foil was too thin to show it clearly
- It sits in a tiny region, so a particle rarely comes near it
- It fills the whole atom, so each particle meets it
Hydrogen gas lit by electricity gives off only a few colors, not a full rainbow. Which idea fits that best, Pia?
- Electrons can have only certain energies, so only certain colors are possible
- Electrons can have any energy, so every color is possible
- The nucleus gives off light as it slowly turns
Two compounds of carbon and oxygen (rounded modern masses)
compound grams of carbon grams of oxygen A 12 16 B 12 32 A carbon atom has 12 units of mass and an oxygen atom 16. Which statement does the table support, Ren?
- B has 16 g more oxygen, so each carbon atom must have picked up 16 more atoms
- B has twice the oxygen for 12 g of carbon, fitting atoms joined 1 to 1 and 1 to 2
- The masses differ, so A and B must be made of two different pairs of elements
Chlorine atoms by mass (rounded isotope data)
mass of atom share of atoms 35 75.8% 37 24.2% Dalton said all atoms of one element have the same mass. What does the table show about that idea, Tala?
- It holds: 75.8% of atoms share one mass, so the others must be errors
- It holds: both masses round to about 36, the same mass
- It fails: chlorine has atoms of two different masses