Atomic Theory

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Across
  1. 2. Cavendish,Discovered hydrogen, which he called “inflammable air,” and showed that water was made of hydrogen and oxygen.
  2. 3. individuals that were part philosopher, mystic, magician, and chemists who tried to change metals into gold. While they did not discover the atom, they developed laboratory techniques such as distillation, heating, and filtering, which later helped chemists study matter more accurately. They also devised chemical symbols.
  3. 5. Heisenberg, Created the Uncertainty Principle, stating that the position and momentum of an electron cannot both be known exactly at the same time.
  4. 8. Curie, Discovered the radioactive elements polonium and radium, showing that atoms could break apart and release energy.
  5. 9. Priestley,: Discovered oxygen by heating mercuric oxide. This showed that air was not one substance but a mixture of gases. At the time, he did not know it was oxygen.
  6. 12. Pauli, Proposed the Pauli Exclusion Principle, which states that no two electrons in an atom can occupy the same orbital and that two electrons in the same orbital must have opposite spins.
  7. 14. Dalton, proposed the modern atomic theory which states:
  8. 16. A Greek philosopher who suggested that all matter was made of four elements—earth, air, fire, and water. This was not an atomic theory, but it laid the foundation for thinking about matter. He demonstrated that air takes up space and must be matter
  9. 19. Chadwick, Discovered the neutron, explaining the rest of the mass of the atom and why atoms of the same element can have different isotopes.
  10. 21. Lavoisier, Known as the “Father of Modern Chemistry.” He discovered the role of oxygen in combustion, named elements, and developed the Law of Conservation of Mass, which states that matter is neither created nor destroyed in a chemical reaction.
  11. 22. Goldstein, Discovered positive particles (later called protons) by observing canal rays in a discharge tube.
Down
  1. 1. A student of philosophy who believed matter could not be divided forever. He proposed that all matter was made of tiny, indivisible particles called “atomos,” meaning “uncuttable.”
  2. 4. Schrödinger, Developed the wave equation for electrons, leading to the quantum mechanical model of the atom, where electrons are found in regions called orbitals.
  3. 6. Boyle, An English scientist who is often called the “Father of Modern Chemistry.” He defined an element as a substance that could not be broken down into simpler substances and supported the idea that matter is made of tiny particles. Also, believed that air was not an element, but a mixture of gases.
  4. 7. Another Greek philosopher who disagreed with Democritus. He believed matter was continuous and could be divided infinitely. His views were widely accepted for nearly 2,000 years, delaying the acceptance of atomic ideas. He believed in the four-element model.
  5. 8. Planck, Introduced quantum theory, suggesting that energy is released in small packets called quanta, which helped explain how atoms absorb and release energy.
  6. 10. Nagaoka, Proposed the “Saturnian model” of the atom, where electrons orbited a positively charged center like rings around Saturn.
  7. 11. Moseley, Discovered that each element has a unique number of protons (atomic number), which determined its place on the periodic table.
  8. 13. de Broglie, Suggested that electrons behave like waves as well as particles, a key part of quantum mechanics.
  9. 15. Bohr, Improved Rutherford’s model by proposing that electrons orbit the nucleus in fixed energy levels, like planets around the sun. This is known as the Planetary model.
  10. 17. Rutherford, Performed the gold foil experiment, discovering the nucleus. He showed that atoms are mostly empty space with a dense, positively charged center.
  11. 18. Millikan, Conducted the oil-drop experiment, which measured the charge of an electron. This led to him calculating the mass of an atom.
  12. 19. J. Thomson, Discovered the electron using the cathode ray tube experiment. He proposed the “plum pudding” model, in which electrons were embedded in a sphere of positive charge.
  13. 20. Faraday, Showed that atoms were related to electricity. His work with electrolysis revealed that electrical charges were involved in chemical bonding. He discovered that atoms could gain electrical charges to form ions.