Zumdahl’s Chapter 1 Chemical Foundations

Chapter Contents Chemistry: “The Science of All that’s Matter” Theory and Experiment Systemé Internationale and English Units Notation and Multipliers Error Analysis Dimensional Analysis Temperature Extensive Properties – E.g., E kin = ½ mv 2 Intensive Properties – E.g.,  = m / V Classification of Matter – Mixtures – Compounds – Elements – Subatomic

CHEMISTRY: The Science of All that’s Matter From subatomic to macroscopic properties From static to dynamic properties From shape to functionality From electronic forces to molar energetics Synthesis, Analysis, Characterization & Utility Interactions of Matter with Matter and Light Understanding Environmental Consequences

Experiment and Theory Observations – Eternal – Reproducible Importance of Records! Inferences Implications leading to new experiments to confirm or deny both inferences and theories Explanations – Tentative – Consistent with all observations! – Suggest new experiments Paradigms – Shifted by inconsistencies Laws of Nature – Impotence postulates Occam’s Razor

Systéme International Units MASS, the kilogram [ kg ] LENGTH, the meter [ m ] TIME, the second [ s ] COUNT, the mole [ mol ] or N Av =  TEMPERATURE, the Kelvin [ K ] ENERGY, the Joule [ J ] = 1 kg m 2 s -2 FORCE, the Newton [ N ] = 1 J m -1

Scientific Notation and Multipliers Dealing with the very small and the very large Scientific Notation: ±  10 ±99 – Addition & Subtraction need common powers. – Multiplication & Division: exponents add & subtract. Scale units with Multipliers ( often by 10 ±3n ) Tera Giga Mega kilo deci centi milli  icro-

Error Analysis Repeated experimental values differ. If tightly clustered, they are PRECISE. If their average falls near the correct value, they are ACCURATE. Quoted as average value ± uncertainty (  ) with units! – ~2/3 fall within  of avg Exact numbers have zero uncertainty, e.g., 1 cal  J

Significant Figures Rules of Thumb: – Multiplication & Division Use the smaller number of significant figures – Addition & Subtraction Use the least significant digit of largest magnitude Zeroes count as significant figures? – Captive & trailing zeroes count; leading don’t. y = f(x 1,x 2,…) and  y 2 =   Xn 2 (  f /  x n ) 2

Dimensional Analysis Add and subtract common units only! Under multiplication and division, units accumulate with + and – powers, respectively. Solution sought must have units identical with that accumulation, or it is not correct. Factor method of unit conversion chains: – [ 10 2 cm / 1 m ] 3  [ 1 L / 10 3 cm 3 ] or 1 m 3 = 10 3 L

Temperature SI unit the Kelvin [ K ] Because 0 K is absolute 0°C = K 0 K = – °C – Different origin but the same size units. T F = 32°F + (9°F/5°C) T C 0 K = – °F 98.6 °F = ? °C

Extensive Properties Scale with the AMOUNT or COUNT Mass and number of moles are obviously extensive. Volume and energies so scale  extensive. Temperature is not extensive! – 2 hot bricks have twice the energy but not twice the temperature of one

Intensive Properties Remain the same under increases in amount or count. Temperature is intensive. Density,  = m / V, is the ratio of two extensive variables; so the amount cancels and  is  intensive.

Phases of Matter Condensed Phases “incompressible” – SOLID, maximally compacted & immobile – LIQUID, molecules not fixed but fluid yet still adjacent to one another; of fixed density Rarified Phases “compressible” – GAS, fluid but nonadjacent molecules expand to fill containers completely (by varying density) – PLASMA, hot, ionized gas of charged atoms & electrons

Classifications of Matter MIXTURES – Separable by physical means E.g., filtration or chromatography – Heterogeneous Components in different phases or domains – Homogeneous Components in same phase and domain COMPOUNDS – Compounded of different elements, but these can be separated chemically ELEMENTS – Identical building blocks, atoms, react identically. SUBATOMIC MATTER – Protons, neutrons, and electrons