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Chemical Fundamentals

Explore the concepts of isotopes, isomers, chemical bonding, molecular shapes, intermolecular forces, acids, bases, and buffers in this comprehensive guide.

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Chemical Fundamentals

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  1. Chemical Fundamentals Ms. J. Smith

  2. Isotopes vs isomers • Isotopes; atoms of an element with same atomic # but different mass # • Isomers; molecules that have same atomic mass but different atomic rearrangement • Radioisotopes; isotopes that can decompose (radioactive) into smaller atoms, subatomic particles and energy • Example; relative abundance & structural stability of C-12, C-13, and C-14 • Half life; time for half of the radioactive sample to decay (rate is constant)

  3. Applications of radioisotopes • Radiometric dating; measuring the C12/C14 ratio of dead organism or fossil • Radioactive tracers in biological research; radioisotopes which flag various molecules and trace their path in vivo • Radioactive tracers in nuclear medicine; diagnosis & treatment of various diseases • I-125 for bone density measurements • I-131 for thyroid monitoring; metabolism • Tc-99; most common radioisotope; lambda = 6 hr

  4. Chemical BondingIntramolecular forces of attraction • Ionic; electrostatic attraction b/w oppositely charged ions eg NaCl • Covalent; electrostatic attraction b/w nuclei and valence e of neutral atoms eg N2 • Electronegativity; a measure of an atom’s ability to attract e of a covalent bond (Oxygen is highly electronegative) • Polar covalent bond; electronegativity difference b/w zero and 1.7

  5. VSEPR & Orbital hybridization

  6. Molecular Shapes • Tetrahedral; CH4 • Pyramidal; NH3 • Angular; H2O • Linear; HCl

  7. Molecular Polarity

  8. Intermolecular bonds

  9. H-bonds

  10. Dipole-dipole attractions

  11. London forces

  12. Acids, bases, and buffers • Ionization (complete vs partial) of HCl vs CH3COOH • Strong vs weak acids and bases • Conjugate acids (proton donor) and bases (proton acceptor) • Buffers; chemical systems that resist significant changes in pH • Buffers consist of conjugate acid-base pairs in equilibrium • Proteins may act as buffers eg hemoglobin

  13. Acid-base Buffer systems

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