Quantum Mechanics Flashcards
The amount of radiant energy emitted by an object at a certain temperature depends on ___
wavelength (E = hc/λ) and E = nhf
Formula for the kinetic energy of an ejected electron (photoelectric effect)
KE = hf - W
Why does an electron not spiral into the nucleus of an atom?
The electron is allowed to occupy only certain orbits of specific energies (the energies are quantized)
Relation between circumference of an allowed orbit and wavelength of an electron
2(pi)r = nλ
Relation between particle and wave properties
λ = h/mv
Heisenberg Uncertainty Principle
Cannot know simultaneously the momentum and position of a particle with certainty
ΔxΔp≥h/4π
Ψ vs Ψ^2
Ψ depends on the location in space of a system
Ψ^2 is proportional to the probability of finding a particle in a certain region of space
- Defines the distribution of electron density in 3-D space around the nucelus
Atomic orbital
Wave function of an electron in an atom
Quantum numbers
Four numbers that describe the distribution of electrons in H and other atoms
- Principal, angular, magnetic, spin
Principal quantum number (n)
- Corresponds to energy of an orbital (only in H)
- Relates to the average distance of the electron from the nucleus in an orbital
Angular momentum quantum number (l)
Tells us the “shape” of the orbitals, depends on n
- has values from 0 to (n-1)
Magnetic quantum number (m_l)
Describes the orientation of the orbitals in space, depends on l
- if l = 0, m_l = 0
- for a value of l, there are (2l+1) integral values of m_l
Electron spin quantum number (m_s)
A spinning charge generates a magnetic field, causing an electron to behave like a magnet
- m_s has values of +1/2 or -1/2
What does the energy of an electron in an atom depend on? (4)
- Angular momentum quantum number
- Principal quantum number
- Sum of orbital energies
- Repulsion between electrons in these orbitals
Simplified electron configuration notation
(n, l, m_l, m_s)
