unit 1 - FOCUS Flashcards

content i need to REVISE (weaknesses)

1
Q

oxalate

A

C2O4 -

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2
Q

atomic absorption spectra

A

element-specific frequencies of electromagnetic radiation at which energy is absorbed when transitioning up from a ground to excited state, represented as a continuous spectrum of light with specific frequencies of light missing (black lines = gaps between energy levels, absorbed by the atom)

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3
Q

atomic emission spectra

A

element-specific frequencies of electromagnetic radiation at which energy is emmited when transitioning down from an excited to ground state, represented as specific frequencies of light (coloured lines on a black background = gaps between energy levels, emitted by the atom)

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4
Q

purpose of monochromator

A

unabsorbed light is focued through a slit, entering a monochromator that separates into specific frequencies and distinguishes wavelengths of interest

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5
Q

water of crystallisation

A

water chemically bonded into a crystal structure of ionic salts (completely embedded as full H2O molecule between lattice gaps)

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6
Q

hydrous salts

A

contain water of crystallisation

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7
Q

quantum dots (what are the compounds)

A

ZnS, ZnSe, CdSe

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8
Q

quantum dots (functions)

A

emit size-dependent wavelengths of light (small = violet, large = red)
used as a biological tracer due to fluorescent microscopy/photometry

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9
Q

dispersion forces (how do they arise)

A

arise in all substances, since electrons are constantly moving, and thus not always symmetrically distributed, resulting in a very temporary/momentary, weak “instantaneous dipole”

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10
Q

factors that influence dispersion forces

A

surface area, mass, number of atoms

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11
Q

how does surface area influence dispersion forces

A

larger surface area => ability of increased proximity between molecules => stronger forces

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12
Q

how does mass influence dispersion forces

A

heavier (more protons) => more electrons => more chance/likelihood AND increased strength of an instantaneous dipole

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13
Q

how does number of atoms influence dispersion forces

A

increased proximity / concentration
more electrons => more chance/likelihood of instantaneous dipole

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14
Q

what are dipole-dipole forces

A

interactions between polar molecules with a partial charge, specifically electrostatic attraction (and repulsion) between physically aligned covalent molecules experiencing temporary, relatively weak, Dipole Moment

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15
Q

factors that influence dipole-dipole forces

A

molecular dipole, size, surface area

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16
Q

how does molecular dipole influence dipole-dipole forces

A

stronger individual dipole => stronger electrostatic attraction => stronger overall dipole-dipole force

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17
Q

how does size influence dipole-dipole forces

A

larger molecule => more electrons => more chance AND increased strength of dipole => stronger electrostatic attraction => stronger force

18
Q

how does surface area influence dipole-dipole forces

A

increased proximity => increased physical alignment => stronger electrostatic attraction (by inverse square law) => stronger forces

19
Q

factors that influence hydrogen bonding

A

atomic radius (inversely)

20
Q

how does atomic radius influence hydrogen bonding

A

smaller atomic radius => electrons confined to a smaller space => increased density => stronger, condensed partial charge => stronger polarity => stronger hydrogen bonding

21
Q

factors that overall impact intermolecular forces

A

atomic radius, mass, surface area, number of electrons, size, molecular dipole strength

22
Q

how do intermolecular forces influence MP / BP

A

stronger intermolecular forces => more energy required to overcome electrostatic attraction and intermolecular forces => increased kinetic energy needed => higher melting and boiling point temperatures

23
Q

vapour pressure

A

tendency of a substance to evaporate

24
Q

how do intermolecular forces influence vapour pressure

A

weaker intermolecular forces => lower boiling points => increased vapour pressure and increased volatility

25
pure substance
substances made of one type of moelcule with a FIXED / CONSTANT / UNIFORM COMPOSITION, AS WELL AS WELL DEFINED, CONSTANT PHYSICAL AND CHEMICAL PROPERTIES
26
surface tension
measure of forces required to strecth or break the surface of a liquid, due to strong cohesive forces (hydrogen bonds)
27
dissociation
ionic substance dissolving into separate, independent mobile ions
28
ionisation
molecule splitting into individual ions, i.e. formation of charges
29
ion-dipole forces
attraction between fully-charged ion and partically-charged dipole, occuring in all forms of dissolution between formed ions and water
30
relationship between solubility of solids and temperature
more kinetic energy => particles able to move more => weakened intermolecular forces => can be overcome with less additional energy => dissociates and ionises more
31
relationship between solubility of gases and temperature
more kinetic energy => particles able to move more => weakened intermolecular forces => more difficult to be "held" by solvent => "escapes" the surface of the solvent
32
types of water pollution
sweage, disease causing aagents, sediment pollution, inorganic plant and algal nutrients, organic compounds, inorganic compounds, radioactive substances, thermal pollution
33
factors of intermolecular forces that influence chromatography
types and charges of polar groups, molecular weight, molecular geometry
34
how does the type and charge of polar groups influence chromatography
molecules preferentially bond with phase having the most similar bonding TYPE (thus the amount of same polar groups as well)
35
how does molecular weight influence chromatography
heavier => larger => more likely to bond with stationary phase and remain in it longer => reduced Rf and increased Rt
36
how does molecular geometry influence chromatography
greater surface area => more likely to bond with stationary phase and remain in it longer => reduced Rf and increased Rt
37
normal phase
stationary POLAR, mobile NONPOLAR
38
reverse phase
stationary NONPOLAR, mobile POLAR
39
mobile phase in PC
solvent (water) progressing along the stationary phase (filter paper) due to capillary action (combination of cohesion and adhesion)
40
advantages of TLC over PC
glass plate is more rigid than flexible paper; easier to control after separation, substances can easily be recovered