Download Chemical_Fundamentals

Chemical Fundamentals
Ms. J. Smith
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)
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
Chemical Bonding
Intramolecular 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
VSEPR & Orbital hybridization
Molecular Shapes
•
•
•
•
Tetrahedral; CH4
Pyramidal; NH3
Angular; H2O
Linear; HCl
Molecular Polarity
Intermolecular bonds
H-bonds
Dipole-dipole attractions
London forces
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
Acid-base Buffer systems