HOW DID LIFE BEGIN
How did organic compounds form?
1. Lightning-driven chemical reactions in the early earth atmosphere
Stanley Miller and Harold Urey in 1953 fired sparks through methane, ammonia, water and
hydrogen. After a week, they identified amino acids (proteins), sugars (DNA & RNA), and
lipids (needed to form cell membranes)
2. In outer space – in dust clouds, comets, meteorites
An amino acid, glycine, was found in material recovered from the tail of a comet
3. At the interface between the ocean floor and heated rock in the earths mantle
STRUCTURE OF ATOM
1. Avogadro: equal volumes of gases contain equal numbers of molecules
a. 2H2+O2 = 2H2O
PHYSICS OF CHEM
1. Generation of electromagnetic radiation by rapidly oscillating electric charge up and
down an antenna. This also produces an oscillating magnetic field perpendicular to the
electric field. They radiate outwards at the speed of light. Radio waves have frequencies
in the 100’s of kilohertz (AM) to 100’s of megahertz (FM). Light waves are produced by
oscillating electric charge in atoms and molecules
2. Rutherford’s atom cannot exist due to clashing theories
Max Planck:
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What is the energy of an oscillator cannot have “any” value, but instead is related to
the vibrational frequency, v:
o E=hv
Where h is a constant we now call Planck’s constant (6.6*10-34 J-s)
if frequency is high, shorter wavelength, few oscillators are energized
if frequency is low, longer wavelength, many oscillators are energized
o photoelectric effect: by Einstein
 if wavelength is too long, increasing intensity will not yield electrons
(infrared)
 if wavelength is short, it will readily eject electrons (UV)
o light acts as a series of particles (photons)
o photon gives up either all or none of its energy to an electron
o if the photon energy is greater than the energy binding the electron to the
surface, it can be ejected
o photons interact with electrons in the metal on a 1:1 basis
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Waves as particles: wave “packets”
o These are localized disturbances in the electromagnetic fields; they have welldefined wavelength and frequency and travel with velocity c
o Localized energy packets
Niels Bohr (1912): theory of H atom
Rutherford’s nuclear atom with the charged electron in orbit around the tiny nucleus,
could not be stable. The oscillating electric charge should produce radiation and thus
continuously lose energy, but it doesn’t.
Bohr: we have to accept nature’s statement that the atom is stable, there had to be certain
stable orbits that don’t produce radiation. Suggested that these orbits had quantized angular
momentum
Bohr worked out the energies corresponding to these angular momentum values
En = - ((2pi2mee4)/(h2))(1/n2)
Energy becomes 0 when n2 becomes infinite
Absorption causes electron to jump to higher n value; emission causes electron to fall to lower n
value
Electron-volt eV
Photons interact with electrons on a 1:1 basis. If electron is at n =4 and drops down to 3, it must
either be at 4 or 3, nowhere between. Because of the 1:1 interaction, there are these sharp
spectral lines
Applying bohr’s theory to helium, was very difficult and they encountered the 3 body problem.
There is no mathematical solution to it.
Bohr’s theory didn’t explain non-radiating quantized energy levels. In 1923, Louis de Broglie
considered the only whole-number properties in science were associated with standing waves.
Possible, like light, thought to be waves, had some properties of particles, so particles such as
electrons might have wave-like properties, and the quantized energy levels in atoms might have
some association with standing waves
Wavelength of a particle:
Photons, quantum theory states E = hv = hc/lamda
Mass and energy: E = mc2
Single photons (electrons) diffract
Wave behavior can be defined like a railroad track, it defines where the train can be in space
regardless of whether there’s a train on the track
Cos curve maps the slope of the Sin curve. It is the differential of the Sin curve
Solutions to Schrodinger’s equation are polynomials that contain integer coefficients n, l, and m
These are quantum numbers that describe the size, shape, and orientation of the standing
wave
The standing wave orbitals are the solutions to the Schrodinger equation
For all values of n, there is only 1 S orbital, 3 P orbitals, and 5 D orbitals
S is spherical, P is dumbbell, D is globe/conical shaped
Number of nodes is n-1
How can we get power from a wave that has an average of 0? We square it
The square of the amplitude is always positive, that’s how we have power for light
The square of the wave function at any point is taken to be the probability of finding the particle
at that point
Probability of finding an electron at a distance, r, from the nucleus: multiply the square of the
wave function by the volume over a radius element dr. when dr is very small, the volume is the
area of the spherical surface, 4pir2 times dr. tnear the nucleus, r approaches zero, so the
probability of finding an electron near the nucleus also approaches zero