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500 BCE
Ancient Philosophers
• Democritus proposes the concept of atoms as indivisible particles that make up all matter. -
Period: 100 BCE to
Alchemy Era
• Alchemists explore the transmutation of metals in search of the philosopher's stone, a legendary substance believed to possess transformative powers. -
Discovery of the Electron
• J.J. Thomson conducts experiments with cathode rays and discovers the existence of negatively charged particles called electrons. -
Rutherford's Gold Foil Experiment
• Ernest Rutherford and his team conduct an experiment in which they shoot alpha particles at a thin gold foil, leading to the discovery that most of the atom's mass and positive charge are concentrated in its nucleus. -
Bohr's Atomic Model
• Niels Bohr proposes a model of the atom where electrons orbit the nucleus in discrete energy levels, and the emission or absorption of energy occurs when electrons transition between these levels. -
Period: to
Quantum Mechanics
• Scientists, including Max Planck, Albert Einstein, and Erwin Schrödinger, develop the principles of quantum mechanics, which describe the wave-particle duality of matter and energy. -
Discovery of the Neutron
• James Chadwick discovers the neutral particle called the neutron, which contributes to the mass of the atomic nucleus. -
Period: to
Subatomic Particle Zoo
• Particle accelerators and detectors lead to the discovery of various subatomic particles, including protons, neutrons, mesons, and baryons. -
Period: to
Development of the Standard Model
• Scientists formulate the Standard Model of particle physics, which describes the fundamental particles of matter (quarks, leptons) and their interactions through electromagnetic, weak, and strong forces. -
Period: to
Advancements in Particle Physics
• Ongoing research at particle accelerators, such as the Large Hadron Collider (LHC), continues to explore the properties of subatomic particles and search for new particles or phenomena beyond the Standard Model. -
Future Discoveries
• The quest to understand the atom and its fundamental constituents is an ongoing endeavor, with future breakthroughs likely to expand our knowledge and deepen our understanding of the universe.