Lecture Notes: Atomic Structure and Atomic Theory

Overview

• Atomic Composition
  • Atoms consist of protons, neutrons, and electrons.
  • Protons and neutrons reside in the nucleus.
  • Electrons orbit the nucleus in specific energy levels or orbitals.

Notations and Abbreviations

• Protons

  • Abbreviated as p+ (with a plus sign to denote positive charge).
  • Can also be denoted as H⁺ in chemistry.
  • One proton in hydrogen atom nucleus, losing its electron leaves H⁺ (a proton).
  • Mass: 1.67272 x 10⁻²⁷ kg (~1 amu).
  • Charge: +1.602 x 10⁻¹⁹ C (approx. +1).

• Neutrons

  • Often abbreviated as n or n⁰ (zero charge).
  • Mass: 1.675 x 10⁻²⁷ kg (~1 amu).
  • Charge: Neutral (0).

• Electrons

  • Abbreviated as e⁻.
  • Mass: 9.10939 x 10⁻³¹ kg (approximately 1/2000 amu).
  • Charge: -1.602 x 10⁻¹⁹ C (approx. -1).

Atomic Concepts

• Atoms are electrically neutral with equal numbers of protons and electrons.
• Ions are charged particles due to unequal numbers of protons and electrons.
  • Cation: Positively charged ion (more protons than electrons).
  • Anion: Negatively charged ion (more electrons than protons).

Isotopes

• Atoms of the same element with different numbers of neutrons.
• Examples in hydrogen:
  • Protium: 1 proton, 0 neutrons.
  • Deuterium: 1 proton, 1 neutron.
  • Tritium: 1 proton, 2 neutrons.

Understanding Atomic Numbers and Mass Numbers

• Atomic Number (Z): Number of protons (defines the element).
• Mass Number (A): Sum of protons and neutrons.
• Isotope Notation: Denotes element, atomic number, mass number, and charge if applicable.

Atomic Structure

• Nucleus: Dense core with protons and neutrons.
• Electron Cloud: Defines volume, mostly empty space.
• Volume vs. Mass
  • Volume is determined by electron movement.
  • Mass is concentrated in the nucleus.

Terms and Concepts

• Atomic Number (Z): Number of protons.
• Mass Number (A): Protons + Neutrons.
• Isotopes: Same element, different neutrons.
• Elements, Compounds, Mixtures
  • Element: Pure substance, single type of atom.
  • Compound: Substance with two or more different atoms bonded.
  • Mixture: Combination of two or more substances, not chemically bonded.

Examining Atomic and Ionic Composition

• Examples of calculating composition:
  • Carbon Isotopes: Carbon-12, Carbon-13, Carbon-14 differ by neutrons.
  • Ions: Sodium ion (Na⁺) and phosphorus ion (P³⁻), analysis of protons, neutrons, electrons.

Conclusion

• Understanding atomic structure is crucial for exploring more advanced concepts like isotopes, ions, and molecular interactions in chemistry.
• Important to visualize atomic structures to comprehend their properties and reactions.