Chemistry 1: Sub-atomic Particles Quiz

Discovery of Electrons

• J.J. Thomson conducted experiments in 1897 using cathode rays, revealing they could be deflected by magnetic and electric fields, indicating they were composed of charged particles.
• Thomson calculated the mass-to-charge ratio of these particles and found they possessed a net negative charge, coining the term "electron" for these subatomic particles.

Robert Millikan's Experiment

• Between 1906 and 1914, Robert Millikan used electrically charged oil droplets to determine the charge of a single electron.
• Utilized Thomson’s mass-to-charge ratio to calculate the mass of an electron.

J.J. Thomson's Plum-Pudding Model

• Proposed in 1904, suggested that atoms consist of a positively charged matrix that holds most of the atom's mass, akin to "pudding."
• Negatively charged electrons were embedded within this matrix like "plums" in a pudding, distributed uniformly, yielding an overall electrically neutral atom.
• Asserted that electrons were fundamental particles that could not be further divided.

Radiation Discovery

• Henri Becquerel discovered that uranium salts emitted a new form of energy.
• Marie and Pierre Curie introduced the term "radioactivity" to describe this emission of energy rays.
• Ernest Rutherford identified multiple distinct types of radiation emitted by compounds containing uranium and other elements.

Discovery of Protons

• Ernest Rutherford's gold foil experiment demonstrated that Thomson's atomic model was inaccurate.
• Introduced the nuclear model of the atom in 1911, featuring a dense, positively charged nucleus at its center, containing most of the atom’s mass.

Rutherford's Nuclear Model

• Proposed that electrons orbit a central nucleus in fixed energy levels similar to planets around the sun.
• Established the concept that atoms are mostly empty space, with orbiting electrons occupying this volume around the nucleus.
• Emphasized that the atom remains electrically neutral, as the positive charge of the nucleus balances the negative charge of the electrons.

Discovery of Neutrons

• James Chadwick utilized beryllium as a target in experiments, bombarding it with alpha particles and observing a penetrating radiation that was neither electrically charged nor affected by electric/magnetic fields.
• Concluded these neutral particles, with a mass slightly greater than protons, are known as neutrons and possess no electrical charge.

Test your knowledge on the fundamental aspects of sub-atomic particles, particularly focusing on J.J. Thomson's Cathode Ray Experiment. This quiz covers essential concepts in General Inorganic Chemistry as part of Quarter 1 Week 2b. Dive into the world of electrons and discover their significance in atomic theory.