Unit 1 - Organic Chemistry Flashcards
What is electromagnic radiaton
Form of radiation released by an electomagnetic process
-physical interaction between charged particles
What happens when charged particles are accelerate
They produce electromagnetic waves
The longer/shorter the wavelength, the greater the energy of the wave
Shorter
What is the electromagnetic spectrum
Range of all possible frequencies in electromagnetic radiation
What does rlectromagnetic radiation include
Light
Xray
Radio waves
Violet = (1) wavelength Red = (2) wavelength
1 longest
2 shortest
Define wavelength
Distance between adjacent crest of wave
What is the adjacent crest of the wave
Highest point
Define frequency
Number of wavelengths that pass a fixed point in time unit
Define valency
Speed of light (constant of 3x10^8)
What is wave particle duality
Electromagnetic radiation can be considered both, waves and particles
What is a quanta
Can transfer a specific amount of Energy
What information can light provide about an atom
Quantity and type
What is an atomic spectra
Caused by electroms moving between different E levels
=fixed for one atom
Quantum theory
Matter can only emit/ absorb E in small fixed amount
When an electron absorbs a photon of E it moves from lower/higher E level to a lower/higher level
Lower
Higher
How is light emitted
When the electron that has been promoted to a higher E level drops back down
What is evidence for the existence of Energy levels
The light E emitted by an atom produces a spectrum that is made up of a series of lines descrete (quantised) E levels
Photons of high/low radiation can transfer greater amounts of energy
High
Radiation is absorben when electrons are promoted to a lower/higher level
Higher
What is an absorption spectrum
Produced by measuring how the intensity of absorbed light varies with wavelength
Why are high temperatures used in emission spectroscopy
To excite electrons within atoms
When e- drops= quantum emitted
What is an emission spectrum
Produced by measuring the intensity of light emitted or absorbed
What is the concentration of an element related to in atomic spectroscopy
Intensity of emitted or absorbed light
What is referred to as ground state
Lowest possible electronic configuration the electrons in an atom can adopt
Levels become closer/further apart as n increases
Closer
What is rhe convergence limit
Point at which E levels become so close together that they converge
State the Aufbau Principle
Orbitals are filled in order of increasing energy
State the Pauli Exclusion Principle
No 2 electrons in one atom can have the same set of 4 quantum numbers
- no orbital can hold more than 2 electrons
- electrons have opposite spin
State Hunds Rule
When degenerate orbitals are available, electrons fill each singly, keeping spins parallel before pairing starts
Why does 4s get filled up before 3d
Because it has a lower energy state
Whats an isolated atom
Exists separately without any bonding
-orbitals in each subshell are degenerate
Whats ionisation energy
Energy required to remove one mole of electron from one mole of gaseous atom
Full shell = (1) = high/low IE
half full shell = (2) = high/low IE
1 very stable, high
2 stable, high
Why is IE higher for stable molecules
More difficult to remove electron
How are covalent bonds formed
Formed when aromic orbitals overlap to form molecular orbital
What are molecular orbitals
Overlapping atomic orbitals
-form covalent bonds
Whats VSEPR
valency shell electron pair repulsion
Theory that pairs of e- that surround central atom of a molecule or ion are arranged as far apart as possible to minimise electron repulsion
What can vsepr be used for
Can be used to predict shapes of molecules and polyatomic ions
What must be considered for vsepr
Bonding and non bonding pairs
Whats a dative bond
Both electrons come from one of the elements involved in bond
-covalent
Why do bonding e- repell less than non nonding e-
Because they are attracted by 2 nuclei
Transition metals have at least one ion with (1)
And incomplete subshell
Are 4s filled before or after 3d for transition metals
Before
High oxidation number= 1
Low oxidation number= 2
1 oxidation
2 reduction
Compounds with high oxidation states 1
Compounds with low oxidation state 2
1 oxidising agend
2 reducing agend
What di transition metal complexes consist of
Central metal ion surrounded by ligands
What are ligands
Molecules/ neg ions that donate electron pairs into unfilled d orbitals
Whats monodentate
Donates 1 e- pair eg water
Whats bidentate
Donates 2 e- pairs eg oxalate
Whats hexadentate
Donates 6 e- pairs eg EDTA4-
What does colour depend on in transition metals
Oxidation state
Properties of ligands (3)
Have at least one lone pair
Usually neg/molecule
What is coordination number
Total number of binds from ligand to central mental
What is the shape of an ion complex determined by
Coordination number
What dies colour of transition metals depend on
Oxidation state
Identity
Ligands attached
Some of visible spectrum absorbed=
Colourr
Non of visible spectrum absorbed
Colourless
All of visible spectrum absorbed
Black
How are transition metal complexes able to absorb light
Because of 5 degenerate d orbitals splitting in terms of energy
What properites does energy have in free transition metal ions
Degenerate
What are ftee transition metal ions
Transition metals with no ligands
What is the spectrochemical series
A list of ligands according to how strongly they split d orbitals in transition metal complexes
Spectrochemical series from strongest to weakest
CN->NH3>H2O>OH->F->Cl->Br->I-
What is crystal field strength
Difference in energy between two subshells of d orbitals
When one colour is absorbed, what colour is emitted
Complementary colour eg green/purple
How do d orbitals split in higher/lower energies
E- present in approaching ligands cause e- in orbutals lying along axes to be repelled
When is light emitted
When e- jump from higher to lower energy level
When is light absorbed
When e- from lower energy level are promoted to higher
What are strong field ligands
More likely to occur in UV region
What are heterogenous catalysts
In different state to reactant
What are homogenous catalysts
Same state as reactant
How can heterogenous catalysts be explained
Formation of activated complexes and absorption of reactive molecules into active site
Presence of unpaired e- or unfilled d orbitals allow complexes to form
How can homogenous catalysts be explained
Changing oxidation states cause formation of complexes
