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88 Cards in this Set
- Front
- Back
What was Dalton's atomic theory that can into question 50 years later?
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that the atom is indivisible.
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Joseph John Thomson
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He realized that the accepted model of an indivisible atom did not take electrons and protons into account. So he referred it to as the "plum pudding atom" where the negatively charged electrons (raisons) are stuck into a lump of positively charged protons (the dough.)
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what was the error in the plum pudding atom and who had suggested it?
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Joseph John Thomson. He didn't mention the number of protons, their arrangement in the atom or th ease with which atoms are stripped to electrons to form ions.
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Ernest Rutherford
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Based on his discovery of the nucleus, he proposed the nuclear atom in which electrons surround a dense nucleus. He thought the rest of the atom as empty space.
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What was the "error" in Rutherford's model?
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People asked, what prevents the electrons from falling into the nucleus?
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Niels Bohr
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Niels Bohr, a young Danish physicist and a student of Rutherford's came up with a new model. He proposed that the electrons are arranged in circular paths, or orbits, the way the plants around in the sun.
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what is an energy level?
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The energy level of an electron is the region around the nucleus where ti is likely to be moving.
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Quantum
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A quantum of energy is the amount of energy required to move an electron from its present energy level to the next higher one.
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Austrian physicist Erwin Schrodinger
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he used new quantum theory: The quantum mechanical model deriving from the Schrodinger equation.
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What are principal quantum numbers?
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n, which is the energy levels fo electrons. They are assigned certain values: n= 1,2,3,4,5,6 etc.
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Within each principal energy level there lies
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several electron cloud shapes.
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When the quantum mechanical model divides the energy level into energy sublevels,
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each sublevel corresponds to a different cloud shape (atomic orbital) which is a region in space where there is a high probability of finding an electron.
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s-shape
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spherical
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p-shape
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dumbell
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d-shaped
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star shaped
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electron configurations
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the ways in which electrons are arranged around the nuclei of atoms
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aufbau principle
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Electrons enter orbitals of lowest energy.
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The Pauli Exclusion principle
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An atomic orbital may describe at most two electrons
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Hund's rule
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When electrons occupy orbitals of equal energy, one electron enters each orbital until all the orbital contains one electron with spins parallel.
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Electromagnetic radiation
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includes radio waves, microwaves, visible light, infared and ultraviolet light, X-rays, and gamma rays.
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The amplitude of a wave is
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the height of the wave from the origin to the crest.
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the Wavelength (the thing that looks like a "person" in chinese character)
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is called lambda, and it represents wavelength (distance between the crests)
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Frequency
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is v, called nu, which represents the frequency, the number of wave cycles to pass a given pint per unit of time.
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The frequency and wavelength of light are ___ related
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inversely.
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Hertz
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In the SI, units of cycles per second are called hertz. Hz.
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When sunlight is passed through a prism the light is separated into a ______ of colors.
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spectrum
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Passing the light emitted by an element through a prism gives the ___ of the element
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atomic emission spectrum.
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Max Planck
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Planck was trying to quantitatively describe why a bod like a chunk of iron changes color when heated.
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h
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planck's constant: 6.6262 x 10^-34 J/s
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How do you find energy?
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Energy of a quantum equals h x v.
E(energy)=h(Planck's constant) x v(nu) |
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Albert Einstein
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Proposed that light could be described as quanta of energy that behave as particles
light quanta=photons |
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What is the photoelectric effect?
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In the photoelectric effect, electrons called photoelectrons are ejected by metals when light shines on them.
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ground state
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when it is at the lowest energy level n=1
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Louis de Broglie
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A french graduate student, asked an important question. Since light behaves as waves and particles, can particles of matter behave as waves?
lanbda= plack's constant divided by mass and v (v being the velocity) De Broglie's equation predicts that all matter exhibits wavelike motions. |
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The Heisenberg uncertainty principle (Werner Heisenberg, a physicist)
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The uncertainty principle states that it is impossible to know exactly both the velocity and the position of the particle at the same time.
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list the visible wavelength in order of increasing wavelength
(The longer the wavelength, the shorter the frequency) |
(highest frequency, lowest wavelength) Violet, blue, green, yellow, orange, red (lowest frequency, highest wavelength)
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list the waves by increasing frequency
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radio waves, microwaves, infared, visible light, ultraviolet, x-rays, gamma rays
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list the waves by increasing wave length
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gamma rays, x-rays, ultraviolet, visible light, infared, microwaves, and radio waves.
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Isaac Newton developed thought of light as consisting of particles, what was so important about that?
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scientists had light as wave length engraved in the minds
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Wave cycle
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each wave cycle begins at the origin, then returns to the origin
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frequency
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nu. the # of wave cycles to pass through a given point per unit of time.
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amplitude
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the height of the wave from the origin to the crest
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wavelength
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is the distance between the crests.
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what was so important about planck's proposal?
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he proposed absorption or emission of quanta of energy. Chemists believed that there was no limitation to the smallness of permissible energy changes in a system. For example, water, seems to have a fixed boiling point but it's just that it's getting hotter by infinitesimally small steps.
E= h x v(nu) (Frequency) |
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Only when you reach the threshold frequency
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do photons move the electrons.
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Why is the photoelectric effect unable to be explained by classical physics?
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because in physics, there is no quantum concept. Classical physics correctly view light as a form of energy. But ti assumed that under weak light, any electron in a metal could "collect" enough energy to be ejected.
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In photoelectric effect, if the intensity of the light is increased, whilst frequency stays the same...
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more electrons bounce off, although they bounce off at same rate.
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In photoelectric effect if the wavelength is shorter, (frequency gets higher)...
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the electron that bounces off, bounces off at a higher speed.
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What's the difference between a quantum and a photon?
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quantum is the amount of energy required to move an electron to one higher energy level whilst a photon are light quantas
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what the difference of an excited and a ground state?
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a quantum of energy whether emitted or absorbed : h x v
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Lyman Series
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ultraviolet light
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Balmer Series
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Visible light
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Paschen series
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Infared Series
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James Clerk Maxwell
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proposed that visible light is composed of electromagnetic waves
waves: A vibrating disturbance by which energy is transmitted |
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Speed of light, C, is
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C= 3 x 10^8 m/s
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electromagnetic radiation is
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energy propagated at the speed of light. C=lanmda x nu
C=wavelength x frequency |
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Hertz=Hz
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frequency= hertz= 1/s= s^-1
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radio waves
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nu: 10^8 lambda: 10^0=1
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James Clerk Maxwell
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proposed that visible light is composed of electromagnetic waves
waves: A vibrating disturbance by which energy is transmitted |
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Speed of light, C, is
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C= 3 x 10^8 m/s
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electromagnetic radiation is
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energy propagated at the speed of light. C=lanmda x nu
C=wavelength x frequency |
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Hertz=Hz
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frequency= hertz= 1/s= s^-1
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radio waves
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nu: 10^8 lambda: 10^0=1
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microwaves. Remember, wavelengths are measured in meters. (m)
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nu: 10^11 Lambda: 10^-3
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infared radiation
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nu: 10^13 Lambda: 10^-3
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visible light
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nu: 10^15 Lambda: 10^-7
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ultraviolet radiation
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nu: 10^17 Lambda: 10^-9
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x-rays
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nu: 10^19 Lambda: 10^-11
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gamma rays
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nu: 10^21 Lambda: 10^-13
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whilst high frequency is short wave length
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low frequency is long wave length
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Max Planck: Energy is always emitted in multiples of
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hv (n) being an integer
Electromagnetic radiation released by an object can have only discrete values, unlike classical assumption of continuous range of values |
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Albert Einstein talked of photons (electrons released by metals)
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hv=binding E + kinetic E
Kinetic E= (1/2mv^2)= hv-hv0 KE=HV-BE |
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photon
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hv. Photoelectric effect, minimum threshold frequency for ejection of electrons
(does not depend on intensity, but rather, frequency) |
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wave/particle duality
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light behaves as either as waves or particles
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Neils Bohr
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explained the emission spectrum of a hydrogen atom on basis on quantization of electron energy
emission spectrum: Light is separated into different components when passed through a prism. |
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A group of hydrogen lines in the visible range is called the
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Balmer's series
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Rydberg constant
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Johannes Rhdberg
1.0968 x 10^7m^-1 1/lambda=R (1/2^2(4)-1/n^2) |
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When is energy emitted?
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when it goes from a higher (excited state) to a lower state. The lowest is called the (ground state)
Bohr thought of orbitals. But electrons can only fit into one orbital, or the other, no in-betweens |
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to calculate difference of energy from one state to the other
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Energy= -2.178 x 10^-18 (1/n^2 - 1/n^2)
the first n being the initial (or final) and the second being the final (or initial) Just make sure it ends up as a positive # |
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Louis de Broglie
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wave/particle duality.
he showed that electrons had wave properties. He asked that if light can behave as particles and waves, can't any other object in nature? Smaller the mass, greater the wave length: lambda= planck's constant/mass x velocity lmabda= h/mv The circumference of a circular orbit has to correspond to a whole number of orbits. |
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Einstein's theory of relativity
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E=mc^2
Energy= mass x (speed of light)^2 |
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werner heisenberg
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uncertainty principle
(change in x)(change in p)=planck's constant/4 x pie (change in= CI) (CI:X)(CI:p)=h/4(pie) X is position: P is momentum |
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Erwin Schrodinger
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wave (quantum) mechanics : Emphasis on wave properties of electron
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principal quantum number:
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n (related to size and energy) always in integral number: 1,2,3,etc
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angular momentum number:
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l (Related to shape of the orbital) Integral values: 0,1,2,(n-1)
when l=0 it's a s orbital when l=1 it's a p orbital when l=2 it's a d orbital when l=3 it's an f orbital |
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magnetic quantum number:
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Ml (related to orientation of orbital in space)
the integral difference of l and -l |
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what is the boundary surface?
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where you'd find 90% of total electron probability. chemists approximate the orbital to the boundary surface.
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Spin Quantum Number Ms
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It has no relation on size, energy, orbital, anything, but it is very important in determining electron configuration. Ms may have any of these two values: +1/2 or -1/2
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