inorganic chem flash - red Flashcards
what is ems
electromagnetic radiation includes x rays and tv signals, different types of ems make up the ems
what produces ems waves
waves are produced by electrically charged particles
what are photons
electromagnetic radiation can be absorbed, when this occurs electromagnetic radiation behaves more like a stream of particles than as a wave. these particles caked photons. therefore say that electromagnetic raduatuin has a dual nature; wave motion and streams of photons
fromula to calc energy of 1 photon
e=hf
what is atomic process that produces atomic emission spectrum
when an atom gains energy it gets promoted to a higher energy level. When the excited electron drops back down to the lower energy level a photon is emitted.
Definition of transition metal
A transition metal has a partially filled d-sub shell in at least one of its valencies, ie when it is an ion
Why are zn and sc not considered a transition metal
Sc has an empty 3D orbital so doesn’t fit the tm definition
Zn has a full d orbital so doesn’t fit the tm definition
Electron configuration within a trans metal
(Fe) => [AR] 4s3 3d6.
As there is special stability, associated with half-filled/ completed filled d orbitals when transition metals atoms form ions electrons form the 4s orbitals are lost first
Oxidation state of a transition metal
Ox state is a change on an ion. TM’s show variable valency. Ie ionisable oxidation states/numbers
The preferred ox state depends on the stability of the ion
.
Why is Fe3+ the preferred ox state of iron
Fe3+ is the most stable as it is half filled
Rules for determining oxidation number of a trans metal
- all free elements have an ox number = 0
- for montomic ions, the ox number is the same as the charge on the ion
- in compounds oxygen has an oxidation number of 2
- hydrogen has an oxidation number of …
- in polyatomic ions the sun of all the oxidation number is equal to the overall charge of the ion
What is oxidation / reduction
Oxidation is an increase I. Oxidation number
Reduction is a decrease in oxidation number
What compounds tend to be ox/reduce agents
Compounds containing metals high oxidation states tend to be good oxidising agents as rhe ions are easily reduced to lower oxidation states, compounds containing metals in low oxidation states tend to be reducing agents
What is a trans metal complex
A TM complex consists of a central metal ion surrounded by ligands, the metal ion is positive and acts as an electrophile
What is a Ligand
Ligands are negative ions with one or more lone pair of electrons that they can donate to the central metal ion, forming dative covalent bonds. A dative covalent bond is one in which both electrons in a bond are donated by one of the atoms.
What are the most common types of ligands
H20 - aqua
Nh3 - ammine (double m)
Fluorine - Flurido
Chlorine - chlorido
Different types of ligands
Monodentate ligands attach to the TM at one point. (Ie donate one pair of electrons)
A bidentate attaches at two points
Hexadentate at 6
Formula for a TM complex
Practice drawing
Rules for naming a TM metal
- number of ligands
- name ligand (if more than one then alphabetical order)
- TM
- oxidation state of TM
Practice negative TM complexes
Sound but x
What causes a line in the emission spectrum
An exited electron returns to ground state, emitting energy difference as visible light of a specific wavelength
Why do the lines converge as they reach the continuum
The energy gaps between energy levels decrease with increasing energy. Ie the higher energy levels get closer and closer together
what does the shape of a tm depend on
the shape depends on the coordination number
why d orbitals in a tm are no longer degenerate
in TM complexes the ligands approach the central metal ion along the x,y,z axis. the electrons in d-orbitals if the metal ion are repelled by the electrons of the approaching ligands, there d-orbitals therefore have higher energy then the d-orbitals that lie between axes. the d-orbitals are no longer degenerate. this is known as the splitting of d-orbitals
what are strong/weak field ligands
strong field ligands are ligands which cause a large difference in energy between the d-orbitals, weak field ligands cause a small difference in energy between d-orbitals (ie orbitals are split less)
what is the spectrochemical series
ligands can be placed in order of their ability to split d-orbitals, this is the electrochemical series
why do TM absorb light
light is absorbed when electrons in a lower d-orbital are promoted to a d-orbital of higher energy. if light of one colour is absorbed, the complimentary colour will be observed
explain why TM are used as catalysts
TMs are used as catalysts because unpaired d electrons or unfilled d orbitals allows intermediate complexes to occur. twos weal’s the covalent bonds inside the reactant molecules, this can provide reaction pathways with lower EA. another reaction is because TM have variable oxidation states, this allows TM to provide an alternative reaction pathway with lower Ea
what is a homogeneous/hetergeneous catalyst
homogeneous catalysts are in the same physical state as the reactants,
the heterogeneous catalysts are in a different physical states to reactants
what is the valency shell electron pair Repulsion rule
VSEPR
states that a molecule will adapt the shape that results in the minimum repulsion between the valency electrons. bonds space out as far as possible from each other to give minimum repulsion forces.
what is the hierarchy of repulsion between electron pairs
LP:LP>LP:BP>BP:BP
what are the rules when working out the shape of a molecule that has no lone pairs
- write formula
- workout how many valency electrons the central atom and other atoms contribute to bonding
- divide by 2 to get the number of bonding pairs
- decide on the basic shape of the molecule.
draw a table showing different shapes of molecules
memorise table
what happens to the shape of molecules when there are lone pairs.
when lone pairs are inverted, the basic shapes are modified because the LP. has greater repulsion than the BP. where all the positions are not equal the LP goes to the site with the least repulsion, ie in the trigonal bipyrimdal this is the equational position. when there is more than one LP they try to get as far apart as possible from each other.
What is continuous spectrum
Continuous spectrum includes all wavelengths of light, it consists of a continuum of wavelengths
What is emission spectrum
The emission spectrum includes only specific wavelengths of light
What is absorption spectrum
The absorption spectrum includes all wavelengths of light with the exception of a small number of specific wavelengths of light. The absorption spectrum of an element is the converse of the emission spectrum of that element
Explain diagram of emission spectrum supports atomic model
When an electron gains energy an electron in the general state can be promoted to a higher energy level ( an excited state). When the excited electron relaxes it drops back to the ground state and gives that energy (emits energy). In the form of a photon of light. The photon of light is a specific wavelength that corresponds to the difference in energy. The greater the energy the shorter the wavelength
Explain diagram of emission spectrum supports atomic model
At higher energy (shorter wavelength) the emission lines become closer together, this evidence supports the modern atomic model - as energy levels get further from the nucleus they become closer together until eventually they merge and form a continuum at n= infinity. The energy gaps between energy levels decrease with increasing energy, i.e. higher energy levels get closer together.
What are orbitals
The area in space where an electron is likely to be forced is called an orbital. Different orbitals are different shapes. S,p,d,f. Each orbital can hold a maximum of 2 electrons
What is an s-type orbital
Spherical shape like a ball. The S orbital in the first shell is smaller than s orbital in the second shell
What is a p-type orbital
The second shells all have p orbitals, in addition to an s orbital. The p subshell has three different p orbitals of the same energy. Orbitals that have equal energy are said to be degenerate. The shape of p orbitals is a dumbbell shape.
What is a d-type orbital
quantum numbers
write out now on paper
State aufbau’s principle
Electrons fill the orbitals in order of increasing energy meaning that the lowest energy subshells are filled first. Of course some sub-shells such as p-subshells and d-subshells have degenerate orbitals
What does hund’s rule state
When there are degenerate orbitals that are available, electrons fill each degenerate orbital singly, and with parallel spins, before pairing up to fill the orbitals
Pauli’s exclusion
No two electrons within the same atom can have the same four quantum numbers. This means that two electrons in the same orbital must have ….. spins
Ionisation energies
Explain the trend in 1st ionisation energy of elements as you go across the period
The general trend as you go across a period is an increase in 1st ionisation energies. However, a decrease can be seen between Be and B, as well as between N and O.
shapes of molecules
go into screenshots now and do it
Order of increasing ems
Gamma ray, X-ray, ultraviolet, visible, infrared, microwave, radio waves
