Quantum Mechanics

Quantum

Quantum is a pack of energy- solved the problem of why diff. wave lengths are emitted in any given amount-- theorized by Planck *this is revolutionary because prior to this, scientists thought that energy could be absorbed/emitted in any given amount

ramp for classical physics

The ramp is adequate in classical physics because the energy can be absorbed on a continuous scale

Schrodinger's Wave Equation

The solutions to Schrodinger's wave equation determine the probability for finding an electron in a particular volume around the nucleus

Why did physicists have to develop new theories of light and energy

The two do not only act in one way- light can be in waves or photons *because: why did the wave length not continuous (ultraviolet catastrophe and the photoelectric effect) -- forced the to come up with a new technology

Pauli Exclusion Principle

each orbital can hold up to 2 electrons which have opposite spin

Why would electrons not want to occupy the same orbital?

electrons are negatively charged and like charges repel each other. so the overall energy of the atom will be lower, if the electrons can distribute in different orbitals

Bohr's Atomic Model

electrons were only allowed to move around the nucleus in certain orbits that corresponded to diff amounts of energy- the small the electron's energy (or energy level) *the difference in energy between the energy levels corresponds to the energy/color of the observed light.

Bohr- light energy levels

in his observations, the difference in energy between the energy levels corresponded to the energy/color of light observed (why the spectrum isn't continuous)- since only certain emerges are allowed only certain colors will be observed

probability in QM model

it's all based on the probability that an electron will be found in a certain location/orbital

Bohr's Atomic model

key features: different energy levels with electrons orbiting the nucleus, with the lowest energy levels closets to the nucleus-- not currently accepted because electrons don't orbit the nucleus and their location can only be predicted

dual nature of light

light can act as both particles and waves

Noble Gas element

represents the atom's inner/core electrons because they have full energy levels

Number of orbitals and electrons in each sub-level

s: 1 orbital 2 electrons p: 3 orbital 6 electrons d: 5 orbital 10 electrons f: 7 orbital 14 electrons

orbitals and max electrons

s: 1 sublevel, 2 electrons p: 3 sublevels, 6 electrons d: 5 sublevels, 10 electrons f: 7 sublevels, 14 electrons

2px v. 3px

same shape (dumbbell), but the 3px is larger and has more capacity for potential energy

Hund's Rule

single electrons with the same spin will occupy each equal energy level before being joined (less resistance and energy spent) *makes sense because particles with the same charge repel one another and would require more energy

Stairs good for quantized energy

stairs are good model because quantized energy is discontinuous-- you can either be at one energy or another but NOT in between

de Broglie proposed

the idea of "matter waves"- that electrons also have wave-like properties, but they are just too small to see

valence electrons from electron configuration

the number of electrons in the highest principle energy level are the valence electrons

Paired electrons

the two electrons with opposite spins are said to be paired

Bohr's Atomic Model failure

though it works for hydrogen, it failed to predict spectra correctly for other elements. Also, later experiments have shown that the idea of electrons "orbiting" the nucleus was not correct.

Schrodinger's wave equations

determine the probably for finding an electron in a particular volume around the nucleus (predicts the orbitals)

Electrons in orbitals (rules)

1. Aufbau Principle 2. Hund's Rule 3. Pauli Exclusion Principle

How did Einstein's theory explain the photoelectric effect?

1. energy absorption is an all or nothing process- an electron either absorbs all of the photon's energy or none of the photon's energy 2. the frequency (or energy) of the photon (and not the intensity/number) is what determines whether or not the photon is absorbed.

n increases

1. energy of the electrons increases 2. the electrons spend more time further from the nucleus so the size of the orbitals increases 3. the energy levels get closer together

QM atomic model organization levels

1. principle energy level 2. sublevels s, p, d, f 3. orbitals px, py, pz, etc.

Quantum Mechanical Model of an Atom

1. the energy of electrons is quantized 2. Electrons behave like waves 3. At any given instant, it is impossible to know the exact position and momentum of an electron *because of the Uncertainty Principle, the quantum mechanical model describes the probability an electron will be found in certain locations

Quantum Mechanical atomic model

1. the energy of electrons is quantized 2. electrons behave like waves 3. at any given instant, it is impossible to know the exact position and momentum of an electron

Max Planck

1858-1947: German physicist who solved the problem of why different wave lengths are emitted at different temperatures- proposed that the energy absorbed or emitted by an object could only occur in "pieces"- which he called quantum

Albert Einstein

1879-1955: German theoretical physicist used Planck's quantum theory to explain the photoelectric effect-- proposed that the light itself consisted of small particles of energy called photons (quanta of energy) *he believed light behaves like a particle, not a wave

Neils Bohr

1885-1962: Danish theoretical physicist- Bohr's Atomic Model (started with the hydrogen atom) he proposed that only certain colors of light were produced because the energy of an electron was quantized (discontinuous)

Erwin Schrodinger

1887- 1961: Austrian theoretical physicist- took over Planck's position after he retired - his wave equation is the basis for the quantum mechanical model of the atom

Louis de Broglie

1892-1987: French theoretical physicist- proposed the idea of "matter waves"- electrons also have wave properties but they are too small to see-- wavelength = h/(mass)(frequency)

Hund

1896-1997: Germany theoretical physicist studied orbitals in atoms and molecules

Wolfgang Pauli

1900-1958: Austrian theoretical physicist- worked with Bohr and determined the Exclusion Principle

Wener Heisenberg

1901-1976: German theoretical physicist- published his theory on quantum mechanics when he was 23- concluded that it is impossible to make a measurement on an object without disturbing the object

Planck's equation

E=hv E: energy, which measured in Joules h: planck's constant- 6.6262 X 10-34 Js v: frequency, which is measured in Hz *gives the relationship between the frequency and the energy of radiation- because that energy is quantized, it is restricted to certain quantities

Explanation of the Photoelectric Effect

Einstein explained the photoelectric effect in that light can exist in the form of photons where the energy is not additive (as it is in waves) but in fact as individual packets of light

Uncertainty Principle

Heisenberg- It is impossible to know both the velocity and position of a particle at the same time

Why can't we see "quantum effects" in our everyday lives

Planck's constant (and the process in general) is so small that the effects aren't visible on a macro scale

Electron configuration

It is the distribution of electrons among the orbitals of an atom- describes where the electrons have a probability to be located and what energies they have-- it's the electrons that come in contact and will determine the chemical properties of that element- also helps determine how many electrons the atom will gain/lose to form an ion

The Pauli Exclusion

It states that each orbital can hold up to 2 electrons and that these electrons must have opposite spin- represented by an up or down arrow

Hund's Rule

It states that single electrons with the same spin must occupy each equal- energy orbital before addition electrons with opposite spins can occupy the same orbitals

Heisenberg's Uncertainty Principle

It's impossible to know precisely both the velocity and the position of a particle at the same time

n

N= the principle energy level *is also the number of sublease in each principle energy level (if n=1, there is one sublevel)

quantum

a piece of energy

s orbital shape

a sphere- gets bigger and has more potential energy as 2s, 3s, 4s, etc.

Aufbau Principle

an electron occupies the lowest energy orbital available

orbit v. orbital

an orbit means the electron is circling the nucleus. an orbital is a generalized location where an electron can be predicted to reside in

unpaired electrons

one electron occupies a given orbital

photons

packets of radiation (that light itself consisted of these things)