Midterm 1

Atom
Discovered by Dalton
Nucleus
Discovered by E. Rutherford and Niels Bohr
Periodic Table
Dmitri Mendeleev arranged/organized first periodicity of elements
Electrons
Discovered by J. J. Thomson
Chemistry
The study of matter, its properties, the changes that matter undergoes and the energy assosiated with those changes
Matter
Anything that has mass and volume
Composition
types and amounts of simpler substances that make up a sample of matter
Properties
Characteristics that give each substance a unique identity
Physical Properties
Those that a substance shows without interaction with another substance
ex: color, melting point, boiling point, and density
Chemical Properties
Those that show once interacted with or transformed into another substance
ex: flamability, corrosiveness
Mass
kilogram (kg)
Length
meter (m)
Temperature
kelvin (K)
Electric current
ampere (A)
Amount of Substance
mole (mol)
Centigrade
Also known as Celcius (C*)
Multiplication/Division Sig Figs
Number of sig figs in the result equals the number in the least precise measurement used in the calculation
Addition/Subtraction
Number of sig figs in the result depends on number of decimal places in least accurate measurement
Accuracy
agreement between measured value and accepted value
Precision
agreement between repeated measurements
Atomic Mass
Number of Protons
Also Number of Neutrons
Isotope
atoms of an element with same number of protons, but different number of neutrons
Avagrado’s Number
1 mole = 6.022×10^23 particles
Frequency
The number of cycles the wave undergoes per second, expressed in units of 1/second = s^-1 = Hz
Wavelength
Distance between any point on a wave and the corresponding point on the next crest (or trough) of the wave
ex: the distance the wave travels during 1 cycle
Amplitude
The height of the crest or depth of the trough
Also known as intensity
Angstrom
10^-10 m
Speed of Light (c)
c = (frequency)(wavelength)
Electromagnetic Spectrum
Highest Energy starting from the left
ex: gamma rays
Longest Wavelength starting from right
ex: radio waves
Max Planck
Developed Quantum Theory to descrive properties of light based on the idea the energy is absorbed and emitted in discrete quanta
Planck’s Constant
h = 6.626×10^-34
Energy
E = nhv
where E is energy, h is planck’s constant, and v is the frequency
hv
the difference between each energy state is the (frequency)(planck’s constant)
Minimum Energy
a photon of minimum E must be absorbed for an e- to be freed. E depends on frequency
Work Function
symbol = O w/ vertical line through it
*also equals (h)(v w/ 0 as subscript)
minimum energy required to release e- from metal surface
Kinetic Energy
KE = (hv) – (work function)
Quantized state
discrete energy levels
(looks like stair steps)
Continuum states
smooth transition between levels
(looks like a ramp)
Bohr Model
E of photon = (E of state a) – (E of state b) = hv
Change in E = (E:final)-(E:initial)
Also = hv = hc/wavelength
Ground & Excited States
Increase = absorption (gain) of energy
Decrease = emission (loss) of energy
Rydberg Equation
1/wavelength = R {1/n1^2 – 1/n2^2}
where R is the Rydberg Constant (1.096776×10^7 m^-1)
De Broglie Equation
E = mc^2
Combine w/ E = hv = hc/wavelength to get wavelength = h/mu where m is mass and u is speed
Momentum (p)
wavelength = h/mc = h/p and
p = h/wavelngth
Wave Function
Describes motion of electron waves as they vary with location and time
Wave function squared defines the orbital of high probability for locating an electron
x

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