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Questions and Answers
Who proposed the idea that all matter is made of small, indestructible units called atoms?
Who proposed the idea that all matter is made of small, indestructible units called atoms?
- John Dalton
- Marie Curie
- Ernest Rutherford
- Democritus (correct)
What significant change did John Dalton make to the understanding of atoms in 1809?
What significant change did John Dalton make to the understanding of atoms in 1809?
- Claimed all atoms are identical in size
- Stated that atoms combine in whole number ratios (correct)
- Proposed that atoms could be created or destroyed
- Identified protons and neutrons
What particle did James Chadwick discover in 1932?
What particle did James Chadwick discover in 1932?
- Photon
- Neutron (correct)
- Proton
- Electron
What did Dmitri Mendeleev contribute to the field of chemistry in 1869?
What did Dmitri Mendeleev contribute to the field of chemistry in 1869?
What was the primary finding of J.J. Thomson regarding the atom in 1897?
What was the primary finding of J.J. Thomson regarding the atom in 1897?
What did Max Planck propose about the nature of energy at the atomic level?
What did Max Planck propose about the nature of energy at the atomic level?
Who discovered the concept of radioactivity in 1898?
Who discovered the concept of radioactivity in 1898?
In the Bohr Atomic Model, what happens when an atom changes stationary states?
In the Bohr Atomic Model, what happens when an atom changes stationary states?
What significant discovery did Ernest Rutherford make through the gold foil experiment in 1911?
What significant discovery did Ernest Rutherford make through the gold foil experiment in 1911?
Which of the following statements is true regarding the quantization of energy?
Which of the following statements is true regarding the quantization of energy?
What did Curie discover emitted radiation from uranium?
What did Curie discover emitted radiation from uranium?
Which equation relates the energy of a photon to its frequency?
Which equation relates the energy of a photon to its frequency?
What problem does the existence of a positively charged nucleus create?
What problem does the existence of a positively charged nucleus create?
Flashcards
Neutron
Neutron
A particle found in the nucleus of an atom, with no charge and a mass roughly equal to a proton. It helps hold the nucleus together.
Quantization of Energy
Quantization of Energy
The theory that energy can only exist in discrete, quantized amounts, not continuous values. It means energy exists in 'chunks' or packets.
Photon
Photon
A packet of electromagnetic energy, often described as a 'particle-like' property of light. It carries light energy and travels as a wave.
Bohr Atomic Model
Bohr Atomic Model
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Quantized Energy Transitions
Quantized Energy Transitions
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Atom
Atom
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Nucleus
Nucleus
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Electron
Electron
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Radioactivity
Radioactivity
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Periodic Table
Periodic Table
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Raisin Bun Model
Raisin Bun Model
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Study Notes
Early Atomic Concepts
- Democritus (400 BC): Proposed the concept of atoms as small, indestructible units ("atomos" - uncuttable).
- John Dalton (1809 AD): Developed an atomic theory, stating atoms are indivisible particles, elements have identical atoms, atoms combine in whole number ratios to form compounds. Dalton's theory couldn't explain how atoms combine, and the question of atom divisibility remained.
Development of the Periodic Table
- Dmitri Mendeleev (1869 AD): Organised elements into a periodic table based on increasing atomic mass. Similar elements were grouped, today's tables arrange by increasing atomic number and include many newer elements.
Discovering Subatomic Particles
- J.J. Thomson (1897 AD): Discovered the electron, a negatively charged particle much smaller than an atom. Modelled the atom as a positively charged sphere with embedded electrons.
- Marie Curie (1898 AD): Discovered radioactivity, the emission of radiation by elements like uranium and radium and polonium. She used radiation quantity to understand element properties.
- Ernest Rutherford (1911 AD): Performed the gold foil experiment, showing the atom is mostly empty space with a dense, positively charged nucleus. Rutherford's experiment contradicted Thomson's model.
Understanding Atomic Nucleus and Subatomic Particles
- The nucleus problem: A positive nucleus should repel itself.
- James Chadwick (1932 AD): Discovered the neutron, a chargeless particle helping hold the nucleus together.
Quantum Theory & Light
- Max Planck (1900 AD): Proposed that energy exists in discrete units (quanta). Energy levels in atoms were quantized.
- Albert Einstein (1905 AD): Established that light also exhibits particle-like properties (photons) and that energy is equal to Planck's constant times the frequency (E = hv).
Bohr Model of the Atom
- Niels Bohr (1913 AD): Developed a model describing atomic energy levels (stationary states). Electrons orbit the nucleus in specific energy levels. Changes in these energy states are quantized. Electrons occupy fixed energy levels and have discrete energy transitions when jumping between levels.
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Description
Explore the foundational concepts of atomic theory and the periodic table through the contributions of key scientists like Democritus, John Dalton, Dmitri Mendeleev, J.J. Thomson, and Marie Curie. This quiz covers the evolution of atomic models and the significance of subatomic particles in chemistry.
