Chapter 3 (1)

Ask, Seek, Knock

• Verse: Matthew 7: 7-8

  • "Ask and it will be given to you; seek and you will find; knock and the door will be opened to you."

Chapter 3: Atomic Structure

• Instructor: Aiye Liang, PhD, Charleston Southern University

Main Topics

1. Experiments in atomic structure development

   • Crooke

   • Thomson

   • Goldstein

   • Millikan

   • Rutherford

2. Discovery and types of radioactivity

3. Atomic structure and the Bohr Model

4. Electron configuration

5. Periodic Table

Learning Objectives

• Explain electrical properties of atoms (3.1)

• Describe atom structure (3.1)

• Discuss experiments leading to X-ray discovery and radioactivity (3.2)

• Distinguish between alpha, beta, and gamma radioactivity (3.3)

• Sketch nuclear model of the atom (3.4)

• List particles in the atomic nucleus with masses and charges (3.5)

• Identify elements and isotopes (3.5)

• Define quantum (3.6)

• Arrange electron shells (3.6)

• Relate quantum energy to orbitals (3.7)

• Write electron configurations in subshell notation (3.7)

• Explain relation of electron configuration to periodic table positioning (3.8)

Importance of Atomic Structure

• Arrangement of atomic parts determines matter properties.

• Knowledge of atomic combinations allows for synthesis of materials.

• Understanding atomic structure is essential for health and medical diagnoses.

Electricity and the Atom

• Electrolyte: Compounds conducting electricity when molten or dissolved.

• Electrodes: Carbon/metallic rods conducting electrical current.

Ion Definitions

• Ion: Charged atom or group of atoms.

  • Anion: Negative ion, moves to anode.

  • Cation: Positive ion, moves to cathode.

Key Experiments

• Cathode Ray Tubes:

  • Crookes discovered cathode rays traveled in straight lines, deflected by electric/magnetic fields.

• Thomson Experiment (1897):

  • Discovered electrons and their mass-to-charge ratio.

• Goldstein’s Experiment (1886):

  • Discovered positive rays from perforated cathodes.

• Millikan’s Oil-Drop Experiment (1909):

  • Measured charge of electron (9.1 × 10^-28 g).

X-Rays

• Discovered by Wilhelm Rontgen (1895).

• X-rays: Forms of electromagnetic radiation, widely used in medical diagnostics.

Radioactivity

• Discovered by Antoine Becquerel (1895); characterized by Marie and Pierre Curie.

• Spontaneous emission of radiation from certain elements, leading to discovery of polonium and radium.

Rutherford Gold Foil Experiment

• Discovered atomic nucleus; majority of particles passed through foil, while some deflected sharply.

• Proposed that most of atomic mass is concentrated in nucleus which contains protons and neutrons.

Isotopes

• Atoms of the same element differing in neutron count.

• Most elements exist in isotopic forms, impacting nuclear reactions significantly.

Electron Arrangement

• Bohr Model: Electrons arranged in ordered fashion, transitioning between energy levels.

• Quantum Model: Electrons described by probability in shaped orbitals; principal energy levels correlate to distance from nucleus.

Relationship with Periodic Table

• Electron configurations correlate with element properties; structured in groups (similar properties) and periods (varied properties).

• Groups defined (1A-8A) by valence electron configurations, with distinct names for certain groups:

  • Alkali Metals, Alkaline Earth Metals, Halogens, Noble Gases.

Green Chemistry and Solar Fuels

• Artificial photosynthesis can generate hydrogen fuel.

• Hydrogen fuel can be utilized to produce heat and electricity through reaction with oxygen.