Atomic Structure & Weighted Atomic Mass

Fill-in-the-blank practice flashcards covering isotopes, average atomic mass, and weighted averages from the lecture notes.

Flashcard 1: John Dalton

• All matter is made of atoms.

• Atoms of an element are identical in matter and chemical properties.

• Atoms rearrange to form new compounds.

• A chemical compound has a fixed atom ratio.
  Model: Billiard Ball Model – atoms are solid, indivisible spheres.

Flashcard 2: J.J. Thomson

Experiment: Cathode Ray Tube Experiment
Findings: Discovered electrons – tiny, negatively charged particles in atoms.
Model: Plum Pudding Model – atom is a positively charged sphere with embedded electrons.

Flashcard 3: Robert Millikan

Experiment: Oil Drop Experiment
Findings: Measured the charge of the electron, which helped determine its mass.
Model: None

Flashcard 4: Ernest Rutherford

Experiment: Gold Foil Experiment
Findings:

• Atom has a small, dense, positively charged nucleus.

• Most of the atom is empty space.
  Model: Nuclear Model – electrons orbit a central nucleus. Discovered the nucleus and proposed that atoms consist of mostly empty space.

Flashcard 5: Niels Bohr

Experiment: None
Findings: Electrons orbit the nucleus in specific quantized energy levels.
Model: Planetary Model – electrons orbit the nucleus like planets around the sun.

Flashcard 6: James Chadwick

Experiment: None
Findings: Discovered the neutron, a neutral particle in the nucleus.
Model: None

Flashcard 7: Erwin Schrödinger

Experiment: None
Findings:

• Electrons are found in probability clouds (orbitals), not fixed paths.

• Their exact location cannot be determined.
  Model: Quantum Mechanical Model – electrons exist in cloud-like regions.