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 = 2 to n = 1 and gives off one photon carrying the energy it lost. How much energy does the photon carry, to 0.01 eV, Bo?
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.
Kira reads the card. Which change to the atom model did the gold-foil evidence force?
- Electrons were put on set energy levels instead of dotted through the atom
- Electrons were added to the atom for the first time, inside a positive sphere
- 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 hydrogen light of 1913, because the colors were few
- The gold-foil test, because particles bounced back from atoms
- 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?
- Electrons are a part of every kind of atom
- Each gas makes its own kind of electron
- Only the gas in the tube contains electrons
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 fills the whole atom, so each particle meets it
- It sits in a tiny region, so a particle rarely comes near it
- It is spread evenly, but the foil was too thin to show it clearly
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 fails: chlorine has atoms of two different masses
- It holds: both masses round to about 36, the same mass
Water has 1.0 g of hydrogen per 8.0 g of oxygen; hydrogen peroxide has 1.0 g per 16.0 g. Zee says they cannot be built from the same atoms. How would Dalton reply?
- He would agree, since a given pair of elements can form just one compound
- He would say the masses must be equal if the atoms are the same, so peroxide is impossible
- Both are hydrogen and oxygen atoms in different whole-number counts, with oxygen doubled