Term 1 Flashcards
How many sub shells are in 1n, 2n, 3n?
n = 1 is 1 s orbital
n = 2 is 1 s and 3 p
n = 3 is 1 s, 3 p and 5 d
What are orbitals?
Orbitals are standing probability waves, - Space around the nucleus that can occupy 2 electrons
What is the principle quantum number?
N (main shell) - size of orbital
What is the angular principle quantum number?
I (sub shell) - shape of orbital
What is the magnetic quantum number?
Symbolized by m, indicates the orientation of an orbital around the nucleus (no. of orbitals in a sub shell)
What is the spin quantum number?
“ms”, tells the direction of the spinning electron, can equal +1/2 or -1/2
What are the 2 exceptions for electron configuration?
Cr and Cu
Cr = 1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d10
Cu = 1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d10
Why does 4s come before 3d?
It has lower energy
What is a becquerel?
A unit of radioactivity equivalent to one nuclear decay per second
1 disintegration/s
Old unit is a curie (Ci - 1g of Ra)
What is ionising power?
How easily electrons are knocked off atoms creating positive ions.
What is an alpha particle?
Two neutrons and two protons, - Larger, can travel only short amount of air before stopping
- Can be stopped by paper
- Very strongly ionizing
E.g Radium Radon + alpha particle (He)
88 protons 86 protons + 2 protons (And 2 neutrons)
Atomic number reduced by 2
Mass number reduced by 4
What is a beta particle?
A fast moving electron
- Electron ejected from nucleus at v high speed, when a neutron changes into a proton and a electron
- Smaller so can travel further before stopping
- Need a few mm of aluminium to stop
- Quite strongly ionizing
Changes to proton and electron
Aluminium silicon + beta particle
13 14 + -1
Since -1 charge lost
Atomic number increases by 1
Mass number doesn’t change
What are gamma rays?
Waves of electromagnetic radiation released by the nucleus
- Can travel long distances
- Stopped by several cm of lead
- Weakly ionizing
- Mass and atomic number not changed at all
What is neutron radioactive decay?
Neutron release
- Causes mass number to decrease by one but atomic number stays the same
What is a Geiger counter?
A gas filled metal tube to detect radiation.
What is the stability of a nucleus?
- Ratio of neutron/proton
- Total charge
Heavy nuclei: - Increasing number of protons
- Increasing charge
Light nuclei: - Odd of neutron/proton ratio
What are heavy nuclei?
- Heavy nuclei (elements): alpha decay and alpha radiation
- 92U 90Th + 2He
- Shift to the left in periodic table, so jump up a row if at end
- 88Ra –> Rn + 2He - numbers must add up
What are light nuclei?
- Light and heavy nuclei: beta decay and beta radiation
- 6C –> 7N + -1e
- Co –> 28Ni + -1e
Light nuclei n/p <1: b+ radiation
- 6C 5B + +1e(a positron)
- +1e + -1e 2y (flash of light)
- Electrons have no mass
What are excited nuclei and excess energy?
- y radiation
- 43Tc –> 43Tc + y (gamma) - more powerful than x-ray
What is a positron?
Positively charged electron
What is positron emission?
Emission of a positron when a proton becomes a neutron
What is orbital electron capture?
- 27Co + -1e –> 26Fe + ve (energy - neutrino) + hv (x-ray)
What is nucleon conversion?
p –> n + +1e
N –> p + -1e
What is the unit for absorbed radiation?
J/kg (Gray) (1 Gy)
What is the unit for biological damage?
Sievert 1 Gy x factor (1 Sv)
What is the action of cosmic rays?
- 7N + n –> 6C + 1H
- Neutrons have no charge but mass of 1
What is transmutation?
The conversion of an atom of one element to an atom of another element
What are the applications of radioactivity?
- Carbon dating
- Radio-immuno assay, radioactive element to be labelled
- Medical - visualization and treatment, PET scans - positron emission tomography
- Energy generation - fission and fusion
What are PET scans?
- Positron emission tomography
- Harmless dose of radioactive glucose introduced in bloodstream
- Shows which areas are most active
What are PET scans used for?
To diagnose cancer, heart disease, and some brain disorders
Detecting the spread of cancer or monitoring the response to cancer treatment. Sometimes used to help diagnose Alzheimer’s disease, and as a research tool to explore brain function.
What is nuclear fission?
A type of nuclear reaction that is used to release energy from large and unstable atoms by splitting them into smaller atoms
What is nuclear fusion?
A nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.
What is a CT scan?
A computed tomography is cross-sectional x-ray images of the brain and spinal cord.
What is a CT scan used for?
Fast imaging, indicates size and location of lesion, helps differentiate between the type of stroke
What is the valence shell?
Shell that provides bonding
- Same down the group
- Outer shell
- Noble gas configuration is most stable valence shell
- All other elements try to gain noble gas configuration = octet rule
- Group 2 lose 2 or gain 6 electrons to gain noble gas config, have 2 valences (2 valence electrons)
How many valences? (bonds)
- Maximum = group number
- Minimum = 8 minus group number
- Main group metals: usual group number
- Transition metals normally have 2
- Count the bonds
What is a crystal lattice?
The symmetrical three-dimensional arrangement of atoms inside a crystal.
- Electrostatic force
- Macroscopic structure
- Class depends on size and charge of ions
Which bond depends on electronegativity?
- Difference is more than 1.7 = ionic
- Difference is equal to or less than 0.4 = covalent
- Difference is in between 0.4 and 1.7 = metallic bonding (0.4 < EN < 1.7)
Oxygen content increases from what to what in compounds?
Ide with least oxygen to ite to ate with most oxygen
What is a hybrid orbital?
Orbitals of equal energy produced by the combination of two or more orbitals on the same atom
- All hybrid orbitals have the same shape
- Bond is rotational
What is a sigma bond?
Overlap of outer orbitals along bond axis
What is a pi bond?
Overlap of orbitals horizontally, weaker than sigma
1 pi and 1 sigma bond
Why can’t double bonds rotate?
- Can’t rotate double bond bc pi bond
- Geometric bonding - restricts rotation and diff groups on each carbon
- Cis (same/sisters) /trans (opposite)
- e/z - enemies/opposite and zamen/same
- Triple bond - one sigma bond and 2 pi bonds
Units for concentration measures
- Partial pressure - Pa, p = p1 + p2 + … = the sum of them
- Amount of substance conc - mol/L, c = n / vol
- Molal concentration - mol/kg (solvent) n/mr
- Mass fraction - kg/kg (%), m/m
What is the concentration in mol/L of 37% m/m hydrochloric acid?
- Trying to work out moles
37% per 100
37g HCl in 100g solution = 370g HCl in 1000g solution
What do you have? Mass of acid in solution, mass of solution
What do you want? No of moles of acid, volume of solution
So how many moles in 37g of HCl
How many litres in 100g solution?
Molar mass: M(HCl) = 36.461 g/mol
M=m/n n = m/M
37/36.461 g/mol = 1.015 mol
So n = 1.015 mole and v = 0.08448L (below)
c = n / V
c = 1.015 mol / 0.08448 L = 12.01 mol/L
How many litres in 100g solution?
Pressure is mass / volume
Volume is mass / pressure
Density p = 1.1837 g/mL
P=m/v
V=m/p
100g/1.1837g.mL = 84.48mL = 0.08448 L
DRAG UNITS ALL THE WAY THROUGH
How to prepare a solution?
Once you’ve calculated the grams of solute necessary for a particular concentration and/or volume of solution, measure the specific amount out and place it in a volumetric flask, then add water up to the volume necessary. It is suggested the solid (salt) is dissolved in a little water, first, since it will make the volume slightly larger as it dissolves - then add water up to the volume necessary.
C1 x V1 = C2 x V2
How to calculate dilutions?
n(solute) = C(solute) x V(solute)
n(dilution) = C(dilution) x V(dilution)
c(solution) x v (solution) = c (dilution) x volume (dilution)
v (solution) = c(d)/c(s) x V(d)
What is the heating curve?
A heating curve is a graph of temperature versus heat added.
- Same amount of energy required for transition between phases
- Under same pressure, bpt and mpt are constants
- Amount of heat required depends on amount of matter
- Bpt depends on pressure
- Heating one thing is the loss of heating from another
What is the critical point?
Highest temp and pressure at which a pure material can exist in vapour/liquid equilibrium
What is the supercritical point?
A substance at temp and pressure above its critical point, where distinct liquid and gas phases do not exist but below the pressure required to compress it into a solid
What is enthalpy?
The heat content of a system at constant pressure
- Energy change, internal energy of the system plus product of pressure and volume, measurement of energy change in a thermodynamic system
What is the first law of thermodynamics?
Energy cannot be created or destroyed
- Matter has an energy content (internal energy)
- Heat is equivalent to mechanical energy
- Energy content can only be changed by heat exchange and work with environment
- Energy cannot come out of nowhere
- No such thing as a perpetuum mobile (a hypothetical machine which once activated would run freely and forever)
- Matter has an energy content: enthalpy, H
- Changes in enthalpy result from adding or removing heat (Q) or by work (W)
- dH = sQ + sW
- Energy can be described by P, V, T, n
- dH = CpdT + Vdp
What is the unit for ideal gas law?
Joule per mole and kelvin per mole, these are both energies
How to calculate reaction enthalpy?
H(products) - H(reagents)
What is Hess’ law?
If a reaction can take place by two routes, and the starting and finishing conditions are the same, the total enthalpy change is the same for each route
- Enthalpy change of reaction is equal to sum of the enthalpies of the reactions into which it may be divided
- Enthalpy of a reaction is independent of route taken as long as start and end are the same
What is entropy?
= measurement of disorder
- Larger entropy = more disorder
- Need to have a positive entropy to react
- All processes and reactions involve a change in enthalpy H and entropy S
What is the second law of thermodynamics?
Every energy transfer or transformation increases the entropy of the universe.
- G = H - T delta S
- Gibbs free energy, G
It is not possible to convert heat completely into mechanical work
- Spontaneous processes are exergonic = one that releases energy
- Non-spontaneous processes are endergonic (ones that require an input of energy)
What is the collision theory?
Need right orientation and energy to successfully collide
What is thermodynamic control?
Reaction that forms the more stable product; requires higher reaction temperature and has a higher activation energy.
- Forms more slowly
- Exergonic reactions will happen
What is kinetic control?
Favored at lower temperatures under equilibrium conditions and has a lower activation energy and thus forms more quickly but is less stable
- Exergonic reactions will only happen once EA is provided
- RT needs to be bigger than EA
What affects K?
Only temperature
But when T increases, K increases
- When EA increases, K decreases
- Catalyst increases K
What is the rate equation?
Rate = k[A]^m[B]^n
What is the transition state?
The intermediate complex formed as covalent bonds in the reactants are being broken and re-formed during a reaction
- Transient
- Very short lived
- Have to go through it
- In between 2 reactions
- Energy barrier
- Stabilize charge
What is binding energy in enzymes?
Helps provide energy to contort molecule to a tetrahedral intermediate to stabilize it
- Peptide bonds can be attacked due to charge relay
What is enzyme inhibition?
- Lots of drugs are proteinase inhibitors e.g HIV drugs
- Mimic transition state
What are the types of inhibitors?
Reversible/competitive inhibitors and irreversible/non-competitive inhibitors
What is reversible (competitive) inhibition?
- Competitor is able to bind to active site as well as substrate, can dissociate again
- No product with competitive inhibitor
- E + S <=> ES <=> E + P
- Reaches maximum velocity slower
- Vmax (maximum speed reaction can go) is the same
- Need more substrate to get to vmax, higher conc of substrate
- Need more substrate to get half of vmax, which is km
- Substrate is unchanged
What is Vmax?
The maximum rate of reaction – when the enzyme is saturated with substrate
What is Km?
Substrate concentration at 1/2 Vmax
Units for conc
What is the equation for Km apparent?
Km app = Km (1+ [I]/Ki)
What is Km apparent?
Km when competitive inhibitor is there - will be higher as will need more substrate in order to fill half active sites
What is Vmax?
The maximum rate of reaction – when the enzyme is saturated with substrate.
What is Km?
Substrate concentration at 1/2 Vmax.
Units for concentration.
What is the equation for Km apparent?
Km app = Km (1 + [I]/Ki).
What is Km apparent?
Km when a competitive inhibitor is present - will be higher as more substrate is needed to fill half active sites.
Measured in presence of inhibitor.
What is Ki?
Inhibitor constant.
Equilibrium constant from binding of inhibitor to the enzyme.
How to determine Ki?
- Rate without inhibitor
- Rate with inhibitor
- Y-intercept when line of best fit extrapolated is -1/Km
- When extrapolated with inhibitor is -1/Km app.
What is irreversible inhibition?
Refers to the prolonged or permanent inactivation of an enzyme, such that it cannot be easily renatured to gain function.
Enzymes can be irreversibly inhibited by compounds that react covalently with groups essential to the enzyme’s activity.
What is myasthenia gravis?
An autoimmune disease that reduces signals by blocking acetylcholine receptors with antibodies.
What is the primary problem in myasthenia gravis?
The problem is at the neuromuscular junction.
How can the condition of myasthenia gravis be relieved?
By raising the concentration of acetylcholine.
What is edrophonium?
A reversible (competitive) inhibitor of acetylcholinesterase used to diagnose myasthenia gravis.
Why is edrophonium not used for treatment of myasthenia gravis?
Because of its short half-life, the effects do not last long.
What is neostigmine?
A drug used to treat myasthenia gravis that binds to acetylcholinesterase and forms a covalent bond.
What is b-galactosidase?
- Natural function is to hydrolyse lactose into Galactose + glucose.
- Also hydrolyses other galactosides like nitrophenylgalactose.
Nitrophenolate ion is yellow.
What is the Michaelis-Menten equation?
V = Vmax([S]/(Km + [S])).
What is the Michael’s-Menten constant?
It measures production over time, can turn that into velocity and can plot it against substrate concentration.
v = velocity, vmax = max. velocity, kM = Michaelis-Menten constant which is the substrate conc that gives half of vmax.
What is the equation for enzyme catalysed reaction?
Km = (k2 + KCat) / K1.
What is the rate of change of [product]?
Kcat x [ES].
V = kcat x [ES].
What is affinity?
How much the enzyme likes the substrate?
What is Kcat?
- A turnover number, productivity, number of products over time, per second, how quickly generates product.
- At enzyme saturation, Vmax = kcat x (Etot).
Etot is total amount of enzyme added to a reaction.
What is the equation including Etot?
Vmax = kcat x (Etot).
