Use the following information to complete the lecture handout.
On tomorrow’s quiz, you will be expected to…
draw the atomic models
match scientists to their experiments and discoveries
place the models in chronological order
Proposed that matter was composed of tiny indivisible particles
Not based on experimental data
Mixture of science and mysticism.
Lab procedures were developed, but alchemists did not perform controlled experiments like true scientists.
based his theory on others’ experimental data
Billiard Ball Model
atom is a uniform, solid sphere
Dalton’s Four Postulates
1. Elements are composed of small indivisible particles called atoms.
2. Atoms of the same element are identical. Atoms of different elements are different.
3. Atoms of different elements combine together in simple proportions to create a compound.
4. In a chemical reaction, atoms are rearranged, but not changed.
spontaneous emission of radiation from the nucleus
alpha () - positive
beta () - negative
gamma () - neutral
Cathode Ray Tube Experiments
beam of negative particles
negative particles within the atom
J. J. Thomson (1903)
positive sphere (pudding) with negative electrons (plums) dispersed throughout
Gold Foil Experiment
Discovered the nucleus
dense, positive charge in the center of the atom
Ernest Rutherford (1911)
dense, positive nucleus surrounded by negative electrons