Atom Structures And Orbitals Flashcards
How do electrons move according to Bohr
In circles around the nucleus
Impossible to know both momentum and position at the same instant
Heisenberg’s uncertainty principle
In Bohr we are only able to describe…
Precise orbit of electron
Wave functions must be
Single valued
First derivatives must be
Continuous
Wave functions must approach — as r approaches —
0; infinity
Responsible for determining the overall energy of an atomic orbital
Quantum number n
Determines angular momentum and orbital shape
QN L
Determines orientation of angular momentum vector in a magnetic field or position of an orbital in space
QN ml
Determines orientation of electron magnetic moment and describes electron spin within orbital
Quantum number ms
A nodal surface is a space with…
No electron density
Build up of electrons in atom results from continuously increasing quantum numbers
Aufbau
Requires that each electron in atom have unique set of quantum numbers
Pauli exclusion
Electrons must be placed in orbitals to give max total possible spin
Hunds
Have the same energy
Degenerate orbitals
Lyman part of spectrum
UV
Balmer part of spectrum
VIS
Paschen part of spectrum
IR
Bohr’s two postulates
Stationary states exist in which energy of electron is constant and characterized by circular orbit around nucleus. Energy of absorbs or emits only when electron moves states
Region of space defined by wave function
Atomic orbital
Constructive wave effect on probability of finding electron in the region
Increases
Destructive wave effect on probability of finding electron in region
Decreases
Larger n means
Higher energy orbital
Lower n means
More compact orbital
All orbitals with a given n value are
In the same shell
Orbitals with the same l value
Same subshell
What does ml do
Distinguishes the individual orbitals
Anticlockwise ms
+ 1/2
Clockwise ms
- 1/2
Radial nodes occur when
Radial component passes through zero
Number of type of node — with energy
Increases
Calculate number of radial nodes
N - l - 1
Radial nodes in 2s
1
Radial nodes in 2p
None
For any series of the same type of orbital, 1st has —- nodes, 2nd has —- etc
None, 1
Orbital with quantum number of l has what number of nodal planes
L number
Bohr radius
0.529 amps
Why was Bohr abandoned
Only works on hydrogen and electrons are not discrete particles
Wave functions can mean either electron is — OR electron is —
A discrete particle with relative probability of one point OR smeared distribution of negative charge with variations in density
Electrons will enter different orbitals for how long
As long as possible
2 electrons occupying different orbitals have
Parallel spins
Parallel spin means
Same direction
Most stable configuration has the largest number of unpaired electron spins
Hunds rule
Paramagnetic
1+ unpaired electrons so molecule is attracted to magnetic field
Diamagnetic
No unpaired electrons so there is weak repelling by magnetic field
Why measure magnetism
Bc it allows us to detect presence and number of unpaired electrons
Electronegativity determined by
Tendency of atoms to bind extra electrons and hold what it already has.
The ability to attract electrons from bonded neighbors
Electronegativity
Binding requires a
Net positive overlap of atomic orbitals
