Biomedical Engineering Lecture 1 Summary

  • Atomic Theory of Matter

    • Founded by John Dalton, stating all matter is composed of atoms.
    • Key terms include elements, compounds, and chemical reactions.

  • Postulates of Dalton’s Atomic Theory:

    1. Matter is composed of indivisible atoms.
    2. An element consists of one type of atom with the same properties (mass).
    3. Compounds are combinations of two or more elements in fixed ratios (e.g., water is H2O).
    4. Chemical reactions rearrange atoms without creating or destroying them.

  • Atomic Symbols and Models:

    • Each element is represented by one or two-letter symbols (e.g., Cl for chlorine).

  • Laws Derived from Atomic Theory:

    • Law of Definite Proportions: Compounds have definite ratios by mass.
    • Law of Multiple Proportions: Ratios of elements in different compounds are whole numbers.

  • Structure of the Atom:

    • Composed of a nucleus (contain protons and neutrons) and electrons surrounding it.
    • Discovery of the electron by J. J. Thomson in 1897 using cathode ray experiments.

  • Nuclear Structure and Isotopes:

    • Nucleus: protons (positive charge) and neutrons (no charge).
    • Atomic number (Z): number of protons, while mass number (A) is the sum of protons and neutrons.
    • Isotopes: atoms with the same atomic number but different mass numbers (e.g., oxygen-16, oxygen-17).

  • Atomic Mass Units:

    • Atomic masses are measured relative to carbon-12 (1 amu = 1/12 the mass of a carbon-12 atom).

  • Periodic Table of the Elements:

    • Elements arranged in rows (periods) and columns (groups) based on their properties.
    • Groups have similar chemical properties (e.g., Group IA: alkali metals).

  • Classification of Elements:

    • Metals (good conductors, malleable), Nonmetals (brittle, poor conductors), Metalloids (semiconductors).

  • Chemical Formulas:

    • Notation using atomic symbols and subscripts indicating relative proportions (e.g., Al2O3 for aluminum oxide).

  • Chemical Bonds:

    • Ionic bonds: formed by transfer of electrons (e.g., NaCl).
    • Covalent bonds: formed by sharing electrons (e.g., H2O).

  • Chemical Reactions:

    • Involve changes in energy and may transform elements into compounds and vice versa.
    • Mass-energy equivalence (Einstein) indicates small mass changes during reactions.