Magnetochemistry Introduction Flashcards
What does magnetism arise from ?
From the electrons in a material and the orbitals they occupy.
What is the relationship between the magnetic force exerted between two poles (p1 and p2) and the distance between them (r)?
What are the two contributions to the magnetic moment of an atom?
The orbital motion of electrons around the nucleus AND the spin of the electrons
What is the principal quantum number (n)
The energy of an electron in atom. Defines which shell the electron is located in.
What is the orbital angular momentum quantum number (l)
Tells us which subshell the election is in.
What is the magnetic quantum number (ml)
Tells us the allowed orientations of the orbital angular momentum in an applied magnetic field. Also tells us how many orbitals are in a subshell.
When n=2 what are the allowed values of l and ml?
2 allowed values of l(l=0 and l=1)
These l values describe the S and P orbitals respectively. For the S orbital ml=0 and for the P orbital ml=(2(1)+1)=3
How do you determine the magnitude of the orbital angular momentum of an electron?
How do you find the orbital magnetic moment of an electron given the orbital angular momentum?
How are the orbital angular momentum and the magnetic moment related?
How are the orbital angular momentum and the magnetic moment related?
How do you work out the magnitude of the angular magnetic moment ?
MB is a unit(Bohr Magnetons)
How do you work out the component of the magnetic moment polarised along a magnetic field?
What unit is used to describe all atomic magnetic moments?
Böhr Magnetons
(Amperes per metre squared in SI units)
What happens to an electrons spin angular momentum when a magnetic field is applied?
It is split into 2s+1 levels described by the spin magnetic quantum number (s)
How do you determine the magnitude of the spin angular momentum of an electron?
What is the component of the spin angular momentum along an applied magnetic field?
Given the spin angular momentum of an electron, how do you determine the magnetic moment that is proportional to it?
How do you determine the magnitude of the magnetic moment associated with the spin angular momentum? ‘
How do you determine the component of the spin magnetic moment polarised along a magnetic field?
What do the orbital (L) and spin (S) angular momenta couple to give?
The total angular momentum, J
How do you determine the magnetisation of a material (total magnetic moment per unit volume)?
When a magnetic field (H), is applied to a material with a magnetisation (M), how is the magnetic induction (B) determined
How do you calculate the magnetic susceptibility?
What are the characteristics of diamagnetic susceptibilities?
Small magnitude, negative and temperature independent.
It arises in materials that have no unpaired electrons, meaning their electron shells are full and have no net orbital or spin angular momentum.
Applying a magnetic field causes a change in the orbital motion of the electrons so we still see an overall magnetic response.
The negative susceptibility means that applying a magnetic field induces a magnetisation that opposes the magnetic field.
What are the characteristics of paramagnetic susceptibilities?
Positive and temperature dependant.
How does a diamagnetic material react to an applied magnetic field?
What is the Meissner effect in terms of magnetic susceptibility,and what does this mean?
How does a paramagnetic material react to an applied magnetic field?
What is the analogy between paramagnetism and ideal gases?
What is Curie’s law?
How can you obtain the curie constant, C ?
How is the curie constant related to effective magnetic moments of atoms in a paramagnetic material? (SI units)
What is the Brillouin function and what is the general shape of it ?
The Brillouin function shows the field dependence of the magnetisation of a paramagnetic at constant temperature. (M vs H plot)
When you know the total angular momentum of an atom (J) how do you calculate its effective magnetic moment?
Don’t need to remember Landé g-factor
How do you calculate the saturated magnetic moment?
How do you determine the effective and saturated magnetic moments of paramagnetic atoms in a material?
What are the allowed values of J for an atom with total orbital angular momentum L, and total spin S?
What is Hunds first rule?
What is Hund’s second rule?
What is Hunds third rule?
What is a term symbol and how do we write one ?
What is the ground state term symbol of Dy^(3+)
What does the spin only magnetic moment assume?
Only the electrons spin is important/ considered.
Orbital angular momentum (L)is quenched due to a strong crystal field.
In which situation is the spin only magnetic moment formula better than Hunds rules at describing effective magnetic moments?
What are the requirements for an electron in an orbital to have an orbital angular momentum?
It must be possible by a 90 degree rotation to transform that orbital into another degenerate one .
What do the A,E and T term symbols mean in a 3d ion in an octahedral crystal field?
They describe the degeneracy of the ion, which allows us to determine whether or not its orbital angular momentum will be quenched. The complete term symbol is then written with superscript 2S+1
Which is the term symbol which retains some angular momentum?
T term ions retain some orbital angular momentum
E.g. Co2+ high spin
How do you calculate the total effective magnetic moment of materials containing more than one paramagnetic ion ?
Need to sum the squares of the individual effective magnetic moments of each ion.
Magnetisations are additive, magnetic moments are not.
What are the spin only effective and saturated magnetic moment formulas?
How do you work out the effective and saturated magnetic moments for paramagnetic ions using Hunds rules ?
