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Final

CHEM 101 Final_Study_Guide

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School
Rutgers University
Department
Chemistry
Course
01:160:161
Professor
All
Semester
Fall

Description
Chemistry Final Study Guide Chapter 1 1.1-1.2 Chemistry: the study of matter and its transformations from one form to another A. Form: a. Shape b. Composition c. Structure d. Properties B. Transformation of one form of matter to another a. Physical change b. Chemical change (reactions) C. Energy associated with: a. The existence of matter b. Transformation of matter Matter: anything that has mass and occupies space Energy: fuel for transformation of matter Physical properties: can be observed and/or measured w/o changing the composition of the substance Intensive properties: scale invariant (independent of size/amt. of material) Ex: properties used to identify matter, T, density molecular weight, color, odor, melting pt, freezing pt, boiling pt, electrical resistivity, thermal conductivity, ductility, malleability, hardness, brittleness - The ratio of two extensive properties gives an intensive property (ex: density) Extensive properties: directly proportional to the scale (proportionally dependent on size/amt. of material) Ex: mass, volume, length, total electric charge 1.3 Hypothesis: idea that is provided as explanation; testable Theory: successful HYPOTHESIS; unifying principle that explains a body of facts and the LAWS based on them; usually suggests new HYPOTHESES and experiments; may have to be modified or discarded (like a LAW) Model: makes a THEORY more concrete Law: statement that summarizes and explains wide range of experimental results and has not been contradicted by experiments; can predict unknown results and also can be disproved or falsified by new experiments 1.5 Physical change: change in the physical properties of a substance with no change in composition g-l-s-g: condensation, solidification, sublimation s-l-g-s: melting, evaporation, deposition Chemical change: chemical reaction Both chem + phys changes involve E transfer (E of phys change < E of chem reaction) Energy: capacity to do work 1.6 Mixture: 2+ substances mixed together, with each substance retaining its identity - Homogenous = uniform (solution): cannot see with naked eye or optical microscope o Ex: air, stainless steel o Solutions o Substances  Element: pure substance that cannot be decomposed  Compound: pure complex substance that can be decomposed - Heterogeneous = non-uniform o Ex: milk, blood, air, oil vinegar salad dressing 1.9 Atomic theory 1. All matter is composed of atoms 2. All atoms of a given element have the same chemical properties 3. Chemical reactions involve joining, separating or rearranging atoms 4. Compounds form by chemical combination of 2+ atoms Law of conservation of mass: there is no detectable change in mass during ordinary chemical reaction Law of constant composition: a chemical compound always contains the same elements in the same proportion by mass Law of multiple proportions: in carbon dioxide the mass of oxygen per gram of carbon is twice as great as in carbon monoxide 2.5 A: mass number (p+n) Z: atomic number (p) N: neutrons (A–Z) Mole: the amount of substance that contains as many particles as there are atoms in 12 g of isotope 12C Molar mass: the mass of a mole in grams Ionic bond: complete transfer of electrons from one atom to another forming oppositely charged ions that attract electrostatically one another IONIC COMPOUNDS DO NOT FORM MOLECULES Covalent bonds: sharing of electrons between the participant atoms Stoichiometry: numerical relationship b/w quantities of reactants and product molecules in a balanced chemical equation 5.3 Redox reaction: all chemical reactions in which atoms change electronic density Reduction: an increase in electronic density (gain of e/hydrogen, loss oxygen) Oxidation: a decrease in electronic density (loss of e/hydrogen, gain oxygen) 7.1 Electromagnetic Radiation (EMR) + Matter EMR = oscillating, perpendicular electric and magnetic fields traveling through space at the same rate Oscillation: variation between alternate extremes within a certain period of time Movement of electric charges produces fluctuations in electric and magnetic fields Wavelength (λ): distance between crests (m) Amplitude (A): height of wave crest (m) Frequency (v): number of complete waves passing a fixed point per unit time (Hz = 1 s )-1 MATH c=λv c=speed (m/s) λ=wavelength (m) v=frequency (/s) c of sound < c of light in air E increases from radio waves (low v, long λ) to gamma rays (high v, short λ) Visible = 400nm-700nm Continuous spectrum (light source, slit, prism (water droplet), photographic film): White light from a lamp contains all wavelengths of visible light When that light is passed through a prism, the different wavelengths are separated We see a spectrum of all rainbow colors Line spectrum: Light from an electrical discharge through a gaseous element (e.g. neon light, hydrogen lamp) does not contain all wavelengths The spectrum is discontinuous with big gaps See pattern of lines, multiple images of the slit 7.3 Heated solid objects emit visible light and the intensity and color distribution depend on T As T (hence E) increase, the λ decrease Quantum theory E is quantized: atoms absorb or emit electromagnetic E only in discrete amts that are whole multiples of a quantum Quantum: smallest amt of E E(quantum) = hv = hc/λ h=Planck’s constant Photoelectric effect: emission of electron by metals when hit by light of certain λ Light striking a photoemissive cathode causes ejection of electrons Ejected electrons reach the anode Results in current flow through an external circuit But not any old light will cause ejection of electrons EINSTEIN: Planck’s quanta: massless particles of light called photons that have both particle-like and wave-like properties E(photon) = hv = hc/λ quantum-photon = E-matter correlation Bohr Model of Hydrogen 1) Only photons with high enough v (short λ) to surpass threshold of E can remove e from certain metal 2) heated solid objects emit continuous spectra, but excited atomic elements emit line spectra and each element has a unique pattern Links: 1) Rutherform: atom = positively charged nucleus surrounded by e 2) Planck: E is quantized 3) Einstein: light is quantized and has a particle-wave dual character E levels are quantized E=0 when the e is located infinitely far from the nucleus (n=infinity) (ex: H+ ion after removing e) Absorption: change in E>0, n increases Emission: change in E<0, n decreases Quantum Mechanical Model of the Atom DE BROGLIE: All moving objects act as waves λ = h/mv = h/p m=mass (kg) p=mv=momentum (kg m/s) therefore: e have wave-like properties HEISENBERG: the uncertainty principle It is impossible to know exactly both the position and momentum of an object (ie change in x = 0 and change in p = 0) (Change in x)(change in p) greater than or equal to h/4pi Change in x = uncertainty in position Change in p = uncertainty in momentum The greater the p, the smaller the change in x Therefore: big objects violate the uncertainty principle cannot be observed for big enough objects SCHRODINGER: the probability-based mathematical model of the atom (the e cloud model) Combines Bohr-de Broglie atomic model with classic equations for wave motion Wave equation: Solutions to wave equation = wave functions = atomic orbitals Electron density = probability of finding e of a given E in a certain space around nucleus 7.5 Quantum Numbers 1. First (principal) quantum number (n): # of orbital types w/ E level Shell = orbitals with same value of n 2. Second (orbital angular momentum) quantum number (L): indicates atomic orbital 3D shape Atomic obritals with the same 3D-shape = subshell Value: 0 to n-1 (ex: 0=s, 1=p,2=d,3=f) Subshell = orbital with same value of n and L Subshells do NOT have equal E; orbitals w/I subshell have equal E = degenerate Ex: E(3s)
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