11. Colour and Magnetism

Question 1

What is the Aufbau principle?

Answer 1

states that in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels (e.g., 1s before 2s). In this way, the electrons of an atom or ion form the most stable electron configuration possible

Question 2

What does diamagnetic mean?

Answer 2

a substance that contains no unpaired electrons and, thus, is not attracted to a magnetic field

Question 3

What is an effective magnetic moment?

Answer 3

the magnitude of paramagnetism expressed by a substance

Question 4

What is a Guoy balance?

Answer 4

a device used to measure the magnetic properties of a sample

Question 5

What is Hund’s rule?

Answer 5

every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin

Question 6

What is magnetism?

Answer 6

a physical phenomenon produced by the motion of electric charge, resulting in attractive and repulsive forces between objects

Question 7

What does paramagnetic mean?

Answer 7

a substance that contains at least one set of unpaired electrons and, thus, is attracted to a magnetic field

Question 8

What is Δoct a measure of?

Answer 8

It is a measure of the electrostatic repulsion between the d-electrons of the metal and the ‘point charge’ ligands

Question 9

Ligands that cause large Δoct ar called what?

Answer 9

Strong field ligands

Question 10

True or False: The size of Δoct affects which orbitals are occupied

Answer 10

True - Δoct determines whether a high- or low-spin configuration is more likely

Question 11

Ions with how many d-electrons have a low-spin configuration?

Answer 11

4-7 d-electrons

Question 12

Why do strong-field ligands have a larger splitting energy?

Answer 12

They bind to the metal ion more strongly increasing the amount of ligand-electron repulsion. This means that they are more likely to exist in a low-spin configuration

Question 13

Which configuration are weak-field ligands likely to exist in?

Answer 13

High-spin

Question 14

What determines the colour of metal complexes?

Answer 14

The colour a complex appears is the complementary colour to the one that it absorbs (i.e. absorbs red, looks green). It is the energy difference between the two non-equivalent orbital sets

Question 15

Which d-orbitals are included in the eg orbital?

Answer 15

dx^2-y^2 and dz^2

Question 16

dxy, dxz, and dyz make up which overall orbital when the d-orbitals are non-degenerate?

Answer 16

t2g

Question 17

What do we use to measure the effective magnetic moment of a substance?

Answer 17

Guoy balance

Question 18

How do we calculate the spin-only magnetic moment?

Answer 18

√n(n+2)

n = number of unpaired electrons

Question 19

True or False: In general, a larger ∆ indicates that lower energy photons are absorbed

Answer 19

False - a larger ∆ indicates that higher energy photons are absorbed, and the solution appears further to the right on the EM spectrum