Definition: The nucleus is the central core of an atom containing protons and neutrons.

Highlight: Bohr's model introduced the revolutionary concept that electrons occupy specific energy levels around the nucleus.

Quote: "The further away from the nucleus, the less energy there is."

Example: The gold foil experiment showed that some alpha particles bounced back from the gold foil, indicating the presence of a dense nucleus.

Definition: Quantum mechanics is the theoretical basis of modern physics explaining behavior at atomic and subatomic levels.

Highlight: The uncertainty principle states that we cannot simultaneously know both the position and speed of a particle with perfect accuracy.

Vocabulary: Quarks are elementary particles that combine to form protons and neutrons.

Example: Modern atomic theory describes atoms as having negatively charged electrons surrounding a nucleus composed of positively charged protons and neutral neutrons.

Definition: Atoms are the basic units of matter that cannot be chemically divided into simpler substances.

Highlight: Thomson's Cathode Ray Experiment proved that atoms contain negatively charged particles (electrons) by showing how cathode rays bend toward positively charged plates.

Example: The plum pudding model depicted atoms as positively charged spheres with electrons embedded throughout, similar to raisins in a pudding.

Vocabulary: Cathode rays are beams of electrons observed in vacuum tubes, fundamental to the discovery of electrons.