Inorganic Flashcards
Name the electromagnetic radiations in increasing frequency
Radiowaves, microwaves, infrared, visible light, ultraviolet, x-ray, gamma
What are photons?
When electromagnetic radiation is absorbed or emitted by matter it behaves like a stream of particles. A photon carries quantised energy proportional to the frequency of radiation.
How are electrons promoted to lower energy levels?
An atom emits a photon of light energy when an excited electron moves from a higher energy level to a lower energy level.
what is evidence for the existence
of these energy levels?
The light energy emitted by an atom produces a spectrum that is made up of a series of lines at discrete (quantised) energy levels.
What is absorption spectroscopy?
In absorption spectroscopy, electromagnetic radiation is directed at an atomised sample. Radiation is absorbed as electrons are promoted to higher energy levels.
What is emission spectroscopy?
In emission spectroscopy, high temperatures are used to excite the electrons within atoms. As the electrons drop to lower energy levels, photons are emitted.
What are orbitals?
electrons behave as waves which vibrate in place. There are different sizes and shapes which are called orbitals. One orbital can hold two electrons
the principal quantum number, n
the main energy level for an electron and is
related to the size of the orbital
The angular momentum number, l
determines the shape of the subshell and
can have values from zero to n −1
The magnetic quantum number, ml
determines the orientation of the orbital and can have values between −l and +l
The spin magnetic number, ms
determines the direction of spin and can have vales of -1/2 or +1/2
The aufbau principle
electrons fill orbitals in order of increasing energy
Hund’s rule
when degenerate orbitals are available, electrons fill each singly, keeping their spins parallel before spin pairing starts
The pauli exclusion principle
no two electrons in one atom can have the same set of four quantum numbers, therefore, no orbital can hold more than two electrons and these two electrons must have opposite spins
orbitals in isolated atoms are..?
degenerate
Why are electrons paired?
Electron pairs are negatively charged and repel each other. They are arranged to minimise repulsion and maximise separation.
What are d-block transition metals?
The d-block transition metals are metals with an incomplete d subshell in at least one of their ions.
Which transition metals are an exception with the aufbau principle?
chromium and copper
Why do chromium and copper atoms not follow the aufbau principle?
These exceptions are due to the special stability associated with the d subshell being half-filled or completely filled.
What happens to the electrons when the first row on transition metals are ionised?
When atoms from the first row of the transition elements form ions, it is the 4s electrons that are lost first rather than the 3d electrons.
How can the same transition metal be different colours?
Compounds of the same transition metal in different oxidation states may have different colours.
What is oxidation?
Oxidation can be defined as an increase in oxidation number.
What is reduction?
Reduction can be considered as a decrease in oxidation number.
What is a ligand?
Ligands may be negative ions or molecules with non-bonding pairs of electrons that they donate to the central metal atom or ion, forming dative covalent bonds.
What is the coordination number?
The total number of bonds from the ligands to the central transition metal.
What happens to the d orbitals in a complex of a transition metal?
they are no longer degenerate
What happens to electrons when a ligand approaches?
Splitting of d orbitals to higher and lower energies occurs when the electrons present in approaching ligands cause the electrons in the orbitals lying along the axes to be repelled.
What are strong field ligands?
Ligands that cause a large difference in energy between subsets of d orbitals are strong field ligands.
What are weak field ligands?
Weak field ligands cause a small energy difference between subsets of d orbitals.
What is the spectrochemical series?
Ligands can be placed in an order of their ability to split d orbitals.
How do we observe colour in transition metals?
Light is absorbed when electrons in a lower energy d orbital are promoted to a d orbital of higher energy. If light of one colour is absorbed, then the complementary colour will be observed
When do electrons transition to higher energy levels?
Electrons transition to higher energy levels when energy corresponding to the ultraviolet or visible regions of the electromagnetic spectrum is absorbed.
What can transition metals act as?
Catalysts
Heterogeneous catalysis
catalysts are in different states from the reactants and are usually
solids. They work by adsorbing reactants onto active sites and weakening the bonds.
This lowers the activation energy. The reactants then collide react and leave the active site for more reactants to be adsorbed.
Homogeneous catalysis
the same state as the reactants and work by a change in oxidation state with an intermediate complex being formed. We can see this in the Rochelle salt reaction which uses cobalt chloride as a catalyst where the oxidation state changes from +2 to +3 then back to +2 when the reaction is finished. There is a distinct colour change from pink to green then back to pink.
