Chem1-_Unit_4.1_Subatomic_Particles__1_.key

Unit Overview

• Unit 4: Going Nuclear!

• Focus Areas: Subatomic particles, radioactivity, and nuclear chemistry.

Content Breakdown

Part I: Subatomic Particles

• Brief History of Electricity

• Discovery of Electrons, Protons, and Neutrons

• Concepts of Isotopes and Ions

Part II: Nuclear Radioactivity

Part III: Nuclear Fission

Part IV: Nuclear Fusion

Learning Goals

• Understand the discovery process of each subatomic particle.

• Recognize the role each subatomic particle plays in atomic structure.

• Utilize atomic symbols to describe atom composition.

• Calculate average atomic mass from isotopic abundances.

• Comprehend the significance and applications of various atomic models.

Essential Questions

• How much empty space constitutes solid objects?

Atomic Models Development

• Historical Context of Atomic Theories

  • Changed perceptions about atomic structure over time.

  • Key Models:

    • Solid Sphere Model (John Dalton, 1803): Indivisible particles.

    • Plum Pudding Model (J.J. Thomson, 1904): Electrons within a positive sphere.

    • Nuclear Model (Ernest Rutherford, 1911): Dense nucleus with electrons orbiting.

    • Planetary Model (Niels Bohr, 1913): Electrons in fixed orbits around the nucleus.

    • Quantum Model (Erwin Schrödinger, 1926): Electrons as wave functions in probabilistic clouds.

Brief History of Electricity

• Early Observations

  • Electric eels and natural phenomena observed by ancient civilizations.

  • Thales of Miletus conduct experiments confusing static electricity with magnetism.

  • William Gilbert differentiates electricity and magnetism (1600s).

    • Named electricus from the Greek word for amber (electron).

• Benjamin Franklin's Contributions:

  • Kite experiment linking lightning to electricity.

  • Developed lightning rods for safe electric discharge.

  • Identified two charge types: positive and negative, along with the law of conservation of charge.

Discovery of the Electron

• JJ Thomson's Experiments:

  • Studied cathode rays leading to the identification of electrons as negative components of all elements.

  • Transition from indestructible models to the Plum Pudding model.

Discovery of the Nucleus and Protons

• Rutherford's Gold Foil Experiment:

  • Revealed dense nuclei through scattering of alpha particles.

  • Concluded that positive charge was concentrated in the nucleus, leading to the discovery of protons.

  • Defined atomic number based on proton count.

Discovery of Neutrons

• James Chadwick's Research:

  • Utilized radiation studies to discover neutrons, aiding in atomic mass understanding and nucleus stability.

• Neutrons and protons exhibit strong nuclear force, acting as stabilizers in the nucleus.

Atomic Structure

• Understanding Atom Composition:

  • Atoms are primarily empty space; electron clouds encompass their size.

  • Nucleus contains nearly all atomic mass; protons and neutrons significantly heavier than electrons.

  • Perception of solidity arises from electron repulsion, illustrating that solid matter is mostly empty space.

Isotopes and Ions

• Defining Isotopes:

  • Same element differing in neutron number.

  • Mass number = total of protons and neutrons.

• Calculating Atomic Mass:

  • Atomic masses on the periodic table represent weighted averages of isotopic abundances.

• Ionic Charge Calculation:

  • In neutral atoms, protons = electrons; charge imbalance leads to ions (Li, Mg examples).

Summary of Atomic Models Evolution

• From Dalton's indivisible spheres to Schrödinger's probabilistic clouds, the atomic model has evolved, reflecting advanced understanding of subatomic particles and interactions.