Atomic Theory Flashcards
How are isotopes distinguished and why?
Isotopes react the same way chemically and thus can be distinguished only by mass separation techniques (such as mass spectroscopy)
Explain the Thomson Experiment
The Thomson experiment demonstrated the existence of opposite charges in an atom and that charge is a fixed quantity. Thomson deflected a stream of charged particles (electrons) using an external electric field (the plates of a capacitor). Because the stream of particles bent in a uniform fashion, Thomson concluded that there was a consistent charge-to-mass ratio for the particles.
What is the mass spectrometer used for in general chemistry?
Charge-to-mass ratio and Isotopic abundance. Recall that isotopes are the same element w/ a different number of neutrons. By sending a charged particle into a perpendicular magnetic field, and observing the degree to which it curves, the isotopes with more neutrons will have a greater radius.
What is the 12C isotope?
The most abundant isotope of carbon.
What is the 13C isotope used for?
It is used in carbon NMR.
What is the 14C isotope used for?
It is used in carbon dating, because it undergoes decay.
What is the 1H isotope?
The most abundant isotope of hydrogen.
What is the 2H isotope used for?
Deuterium is used in proton NMR solvents.
What is the 3H isotope used for?
Tritium is used in radio-labeling experiments.
What is the 235U isotope used for?
It is used in nuclear fission.
What is the 238U isotope?
It is the most abundant isotope of uranium.
Explain the Millikan Oil Drop Experiment.
Its aim is to suspend a charged oil drop in an electric field to find the charge of an electron. If the particle is suspended (or falling at a constant velocity), then the net force is zero, so mg = -qE. Because we know g and we can set the electric field strength (thus we know E), by plugging in the average mass of an oil drop, we can solve for q, the charge of the electron.
What experiments address “what the are” questions about subatomic particles?
The Thomson experiment, the Millikan oil drop experiment, and the use of the mass spectrometer.
What experiment addresses “where they are” questions about subatomic particles?
The Rutherford experiment.
Explain the Rutherford Experiment.
It determined that atoms have dense nuclei with nearly all of the atomic mass centrally concentrated, and that metals have uniformly spaced atoms in the microscopic composition. An incident beam is focused ant a thin slice of gold. Because the incident beam mostly passes straight through the sample, with deflection being observed in only a few cases, it is concluded that the atom is made up predominantly of empty space. The mass occupies very little space and is not spread uniformly.
What equation describes the energy of a photon?
E = hv = (hc)/λ
What does “spin up” imply about the electron?
The spin produces a magnetic field vector oriented upward.
Describe paramagnetic and diamagnetic.
Paramagnetic–unpaired electrons.
Diamagnetic–paired electrons.
Pauli’s exclusion principle.
No two electrons can have the same set of quantum numbers.
Hund’s rule.
Electrons completely fill lower energy levels before starting to fill higher energy levels.
Aufbau principle.
Electrons are added one by one to the shells, starting with the lowest energy level.
Explain exceptions to the Aufbau principle.
Half-filled d-shell stability is seen with chromium, molybdenum, and tungsten. Filled d-shell stability is seen with copper, silver, gold, and some say platinum.
Why is the x-axis orientation of an orbital have the magnetic number (m_l) of -1?
That’s just the way they do it. Just as x comes before y and z in the alphabet, -1 comes before 0 and +1 numerically.
What are the four periodic trends as you move up and across to the right of the periodic table?
Atomic size decreases
Ionization energy, electron affinity electronegativity increases
The trend in electronegativity increases with which of the following? Ionization energy Atomic radius Atomic number Number of valence electrons
number of valence electrons
All alkali metals react favorably with water. What is the generic reaction?
2 M(s) + 2 H2O(g) –> 2 MOH(aq) + H2(g)
What oxides are formed when alkali metal react with oxygen?
Lithium forms an oxide (M2O)
Sodium forms a peroxide (M2O2)
Potassium, rubidium, and cesium for superoxides (MO2)
Besides reacting with oxygen, alkali metals are oxidized by what?
Halogens, nitrogen, and hydrogen.
Alkaline earth metals, except for beryllium, react favorably with water. What is the generic reaction?
M(s) + 2H2O(g) –> M(OH)2(aq) + H2(g)
Alkaline earth metals react favorably with oxygen. What is the generic reaction?
2 M(s) + O2 –> 2 MO(s)
Beside reacting with oxygen, alkaline earth metals can be oxidized by what?
Halogens, nitrogen, and hydrogen.
Which series emits photons in the visible spectrum?
The Balmer series.
What is the common usage for AM and FM EM radiation?
AM–Cheaper radio communication
FM–Expensive radio communication
What is the common usage for microwave and infrared EM radiation?
Microwave–Satellite, cell phones, radar, heating water.
Infrared–Line-of-sight com, molecular ID, heat
What is the common usage for visible and ultraviolet EM radiation?
Visible–vision, fiber optic communication
Ultraviolet–Bond-breaking, exciting electrons
What is the common usage for X-ray and Gamma EM radiation?
X-ray–Nucleus detection, core e- ionization
Gamma–Nuclear excitation
What are the two types of color to consider?
Emitted and reflected.
Describe reflected color.
It is the color we observe which is the complementary color of the frequency that had the highest intensity of absorption.
Describe the photoelectric effect.
An incident photon causes the release of an electron.
hv = ϕ + 1/2 mv^2
= energy to eject + kinetic energy of ejected e-
α-Decay of 120/50 X element
120/50 X –> 4/2 α + 116/48 Y
β-Decay of 120/50 X element
120/50 X –> 0/-1 e + 120/51 Z
β+-Decay of 120/50 X element
120/50 X –> 0/1 e + 120/49 Q
γ-Emission of 120/50 X element
120/50 X –> hv + 120/50 X
α-Capture of 120/50 X element
120/50 X + 4/2 α –> 124/52 A
β-Capture of 120/50 X element
120/50 X + 0/-1 e –> 120/29 Q
β+-Capture of 120/50 X element
120/50 X + 0/1 e –>120/51 Z
γ-Absorption of 120/50 X element
120/50 X + hv –> 120/50 X
What is ionization energy proportional to?
Z^2
