Many Electron Atoms Flashcards
(35 cards)
What is the many body problem
Where we must consider simultaneously the effect of the nucleus and each of the other electrons
Spectroscopic Notation
Use letters to stand for different l (angular momentum) values
Spectroscopic Designation
0 - s
1 - p
2 - d
3 - f
4 - g
5 - h
6 - i
(must get it starts from 0 to increase flashcard rating)
Pauli Exclusion Principle
No two electrons in a single atom can have the same set of quantum numbers
What governs the binding of electrons to an atom
Attraction of atomic nucleus - an electromagnetic interaction
Depends on distance and charge
Electron configuration of alkali elements and importance
Single s electron outside an inert gas core
Very reactive elements as they can easily give up the s electron to another element to form a chemical bond
Electron Screening
To an outer electron - charge of the nucleus can be screened or shielded by the electrons in the inner shells
What does the quantum number n determine
The atomic shell
Quantum number designation
1 - K
2 - L
3 - M
4 - N
5 - 0
Kante Likes Meeting New Openings
What are subshells
Levels with a certain value of n and l
Rules for filling the electronic subshell
The capacity of each subshell is 2(2l+1) - P.E.P
Electrons occupy the lowest energy states available
How to indicate the electron configuration of each element with an example
Use a notation in which the identity of the subshell and the number of electrons in it are listed
Hydrogen has a configuration of 1s^1 and Helium has a configuration of 1s^2
N*L^2s+1
Principles of Elements
Filled subshells are normally very stable configurations
Filled subshells do not normally contribute to the chemical or physical properties of an atom - only electrons in unfulfilled subshells need to be considered
Atomic Trends
Atomic Radii - P subshells have a smaller atomic radius - due to an increase in atomic nuclear charge while shape of the orbit remains the same - nucleus pulls in electrons to smaller orbits
Ionization Energy - inert gases have entirely filled subshell and have larger ionization energies than neighbouring elements because of the extra energy needed to break open a filled subshell
Electrical Resistivity - Good electrical conductors require delocalised electrons
Magnetic Susceptibility - Magnetic properties of the Lanthanides are even stronger than the transition metals due to larger angular momentum of f subshell
Binding energies of the outer electrons in a typical atom
Only of the order of several eV and so it
takes relatively little energy to move an outer electron.
What happens when we excite one of the outer electrons in an atom to a higher energy level
Resulting vacancy can be filled by electrons dropping into the empty state
Selection Rules
Δl = ±1
Δml = 0, ±1
Δmj = 0, ±1
Optical Transitions and Zeeman Splitting
Optical spectra arise from transitions of valence electrons.
Optical photon energies are approx. several eV.
Inner electrons are left undisturbed by optical transitions.
When are charactersistic X rays emitted
In transitions between the more tightly bound inner electron levels of an atom
What is the energy of the X-ray photon emitted equal to?
The energy difference between the initial and final atomic levels of the electron that makes the transition
What are Characteristic X rays known by
The vacancy that they fill, not by the shell from which they originate
What does characteristics of X ray spectra depend on
The binding energies of the electrons in the inner shells
With increasing atomic number Z, these binding energies simply increase uniformly
Moseley’s Law
ΔE = (10.2eV )(Z −1)^2
For X-Rays
Dependence of X-Ray energies on Z
Equation for Total Orbital Angular Momentum
Vector sum of the orbital angular momenta
Have to obey the rules of quantum mechanics
