CHEM 101 Lecture Notes Week 2
CHEM 101 Lecture Notes Week 2 CHEM 101
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This 5 page Class Notes was uploaded by spencer.kociba on Wednesday October 12, 2016. The Class Notes belongs to CHEM 101 at Drexel University taught by Monica Ilies in Fall 2016. Since its upload, it has received 10 views.
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Date Created: 10/12/16
Spencer Kociba CHEM 101 Lecture notes Lecture 09/27/16 ● Physical Properties ○ Intensive physical property= does NOT depend on the amount of matter in substance ■ Ex. odor, color, melting/freezing point, density ○ Extensive physical property= DOES depend on the amount of matter in a substance ■ Ex. mass, weight, volume, length ○ Chemical property=quality that can only be established by changing a substance’s chemical identity (ex. Gasoline into carbon dioxide) ○ Physical property= used to describe the original composition of a substance (ex. Gasoline is clear) ● Density ○ Mass per unit volume ○ D=m/v ○ Intensive physical property ● Unit conversion problems ○ Aka dimensional analysis ○ Unit equations convert from one unit of measurement to another ■ Like 2.54=1in 1km ○ Conversion factor ( ) 1000 m ○ Information given x conversion factor(s) = information sought ○ ● The Mole and Avogadro's number ○ Avogadro’s number: an approximation based on Carbon 12 23 ○ 1 mole= 6.022∗10 items ○ ^conversion factor used in chemistry usually references x mol of atoms or molecules ○ ■ 39.0983g K atoms (the conversion factor) ■ 1 mol K atoms ○ ■ ^^^same thing works for molecules, but mass is the molar mass aka the combined atomic masses of the molecule multiplied by their frequency in the molecule (ex. In water, hydrogen appears twice and oxygen appears once) ○ Use atomic mass for 1 element or an atom ○ Use molar mass for compounds, molecules, diatomics, etc. Spencer Kociba CHEM 101 Lecture notes Lecture 09/29/16 Introduction to Quantum Mechanics Main idea: microscopic/nanoscopic particles behave MUCH differently than macroscopic particles ● Subatomic particles exist in 2 conditions (natural duality) ○ Electrons have particulate behavior like having mass and volume, but also energy characteristics like a wave ○ (wave AND a particle) ● Light is created by 2 oscillating waves (electric and magnetic field) ● c=3.0∗10 m./s the speed of light (in m/s) ● Parts of a wave in light ○ amplitude=brightness ○ frequency =wavelength dependent ○ Energy is proportional to amplitude, but in a direct relationship with frequency ○ frequency=c formula to calculate frequency λ (Hz) using c anλ (wavelength) ○ ● Explaining the photoelectric effect ○ Electrons emitted from the metal surface when light is being transferred to those electrons ○ Classic theory: shorter wavelength of light or greater intensity (amplitude)=more electrons ■ < direct relationship ○ Einstein’s Theory ■ When a beam of light hits the surface of the metal, the electrons are emitted with kinetic energy ■ Energy=h*frequency −34 ■ h=6.626∗10 J∙sec Planck’s constant ■ ■ ■ ■ Main idea: the electrons are emitted in individual energy steps (not constant as energy increases) ■ Binding energy is denoted by ϕ ■ More energy in the system=electrons emitted at a higher KE ■ KE=E❑ phton❑ binding ■ KE=hν−ϕ ● hv=quantized packet (energy in steps ● hv=quanta of photons ■ Energy & frequency=directly proportional ■ Energy & wavelength=inversely proportional ○ When atoms/molecules absorb energy, that energy is usually released as light energy ○ Pattern of light passing through a prism is unique to that type of atom or molecule ■ Pattern of light=emission spectrum