Chemical Principles Åk 1 Flashcards
Var på y-axeln börjar kurvan på en s orbital och hur ser kurvan ut beroende på noderna? Hur ser Ψ, Ψ^2 och 4pir^2 Ψ^2 kurva ut?
Den börjar högre upp på y-axeln. Först ritar man kurvan som vanligt med Wavefunction Ψ och alla noder så ifall n=3 ska den ha 3 kurvor. Sedan blir Ψ^2 och alla kurvor som passerar under x-axeln blir positiva och alla 3 kurvor är på den positiva axeln. Sedan börjar man med den minsta kurvan, näst minst och störts. Så ser kurvan då ut.
Var på y-axeln börjar en p orbital och hur ser kurvan ut? Hur ser Ψ, Ψ^2 och 4pir^2 Ψ^2 kurva ut? Hur ser kurvan ut beroende på noderna?
Den börjar vid origo. Först ritar man kurvan som vanligt med Wavefunction Ψ och alla noder så ifall n=3 ska den ha 2 kurvor. Sedan blir Ψ^2 och alla kurvor som passerar under x-axeln blir positiva och alla 2 kurvor är på den positiva axeln. Sedan börjar man med den minsta kurvan, näst minst och störts. När man sen skriver 4pir^2 Ψ^2 så börjar den vid origo.
Kurvorna är lika med mängden noder-1
Vad indikerar MO theory och hur ser dess diagram ut?
MO Theory = Molecular orbital diagram. Visar hur de olika elektronerna ligger i sigma och pi bindningarna när elektroner binder ihop sig. alla valenselektroner är dilokaliserade runt molekylen.
Man börjar med sigma sen sigma.
Sedan: pi, sigma sen pi,sigma*.
Hur beräknar man Bond order?
((Number if electrons in bonding orbitals- number of electrons in anti bonding orbital)/2).
Du räknar antalet elektroner som är bonding så i 2s^2 är det 2 elektroner, sedan subtraherar du med mängden elektroner som är i antibonding orbitalen och dividerar sedan med 2.
What is a Lewis structure and how do you Apply it to a molecule
Lewis structure tells you how where and how many electrons are located around an atom and how they are bonded in a molecule.
You start by counting the valance electrons on each of the atoms and then transfer the cations electrons to the anion and draw the bond. The anion is the atom who’s more electronegative
What is lattice energy?
The difference in energy between the ions of a compound separated as a gas and packed together in a solid.
Whats a lone pair?
A pair of valance electrons had doesnt participate in bonding (anti bonding)
What’s the octet rule?
Atoms in covalent bonds go as far as possible to complete their shells with electrons by sharing the electrons
What’s a central and terminal atom?
Central atom: bonded to at least two other atoms and is the center of the molecule, it’s written first in the molecules name.
Terminal atom: an atom bonded to only one other atom
How are acids compound name written?
An H is written first on the compound
What does resonance mean? How is the molecule written according to the energy?
Blending of Lewis structures of a molecule. Occurs when there’s a double bond that rotates all around the the molecule because of their symmetry and final charge.
The chosen resonance structure always contributes the most to the lowest energy. Resonance structures with the same structures (symmetrical) contribute with equal energy to the resonance structure
What does formal charge mean and how do you apply it?
What is it’s equation?
What is said about the Lewis structures formal charge?
Formal charge equation: valence electrons - (lone pairs + bonding electrons/2)
The formal charge is the charge the of an atom it would have if the bonding were covalent.
The arrangement of a molecule with the lowest formal charge results in the lowest energy.
What is a dipole-dipole bond? And what does electronegativity has to do with it?
a dipole dipole bond is when two or more atoms share the the electrons but one is more electronegative than the other which makes easier for it to pull the other electrons from the atoms toward it.
The greater the electronegative the atom is the greater it’s pull on the other atom is and the harder it is for the atom to loose its electrons.
What does low- and high ionizing energy indicate?
Low ionizing energy = low electronegative atom, takes little energy to remove electrons from it.
High ionizing energy = high electronegative atom, takes a lot of energy to remove electrons from it.
Name a weak and strong acid. How do their balanced equation look?
Strong acid: H2SO4 (svavelsyra, you use a normal arrow because it proteolyses the whole way ->)
weak acid: HAc (acetic acid) you use equilibrium arrows
What does bond strength mean and how do you calculate it?
It’s the strength of a bond between 2 atoms. It’s measured by the energy required to separate the bonds.
You draw the molecule and add together all the bonds energies you see which results in the molecules strength.
Namn the 4 strongest Bonds from strongest to weakest
Coulombic attraction,dipole-dipole, hydrogen bonds and London dispersion.
What’s the VSEPR model?
By it’s 4 rules it explains in what angles the atoms in the molecule are bonded.
What’s the 1 rule of the VSEPR model?
Regions with high electron concentration (lone pairs on the central atom and bonds) repel each other. The repulsion is minimized by moving these regions as far away from each other as possible.
What arrangement gives the electron arrangement?
The most distant way the electrons/atoms lie to each other in a molecule
What’s the 2 rule of the VSEPR model?
A multiple bond is grated as a single region of high electron concentration. Ex a double bond repel other atoms/lone pairs as one unit
What’s the 3 rule of the VSEPR model?
All regions of high electron concentration, lone pair and bonds, are included in the description of the electron arrangement but only the positions of the atoms are considered when identifying the shape of the molecule
What’s the 4 rule of the VSEPR model?
Strengths of repulsion:
Lone pair-lone pair > lone pair-atom> atom-atom
What’s a polar molecule?
A molecule with dipole-dipole moments.
What’s a non polar molecule?
A molecule with zero dipole-dipole moments
What’s the VB (valence bond) theory?
The description of covalent bonding in terms of atomic orbitals sigma and pi.
What sigma and pi bond indicates a single, double and triple bond?
Single bond: 1 sigma bond
Double bond: 1 sigma and 1 pi bond
Triple bond: 1 sigma and 2 pi bonds
What do the sigma and pi boxes look like? How many electrons fit in them
Sigma = 1 Box that can fit 2 electrons Pi= 2 boxes that can fit 4 electrons
Whats a bonding and antibonding orbital?
Bonding orbital = doesnt have * marked on it and it participates in the bonding with the atoms
Antibonding orbital= has an * marked on it, doesn’t participate in the bonding between atoms in a molecule
*What does isothermal mean? And what happens during it?
Constant temperature.
What does diffusion mean?
One substance goes through another one
What does effusion mean?
The escape of gas through a small hole towards a region with lower pressure
Name the three different phases.
Solid liquid gas (vapor)
What does hydration mean? How does it occur?
When water dissolve solute particles by surrounding (H2O) its ions and separating them.
It occurs through the polar characteristics from water.
What’s an ion-dipole interaction?
The interaction between a dipole molecule and ion. It arises from the partial charges on the dipole molecule which binds together with the opposite charge from the ion (- with +)
What’s a dipole-dipole interaction?
The interaction between dipoles (polar molecules), the positively charged cations on one dipole bind together with the negative charge anion from the other dipole
What are London forces? Between what molecules does this occur?
It’s the weakest bond and the attractiveness from non polar molecules. It’s only between monatomic gases (same atoms gas) and non polar molecules.
What is the van det waals interaction?
Interaction between a dipole and non dipole molecule (polar with non polar). The non polar molecule becomes polar permanently when it approaches the dipole molecule. Ex O2 and H2O.
What is a hydrogen bond?
When a hydrogen atom is bonded to a strongly electronegative atom (often N, O, F). It’s the strongest intermolecular interaction.
In what 2 parts is the universe divided in? Give examples on both of them
System (a reaction mixture) and surroundings ( water bath)
What’s an open-/ closed and isolated system?
Open system: can exchange both matter and energy with the surroundings
Closed system: has a fixed matter but can exchange energy
Isolated system: can’t exchange either of them
What does internal energy (U) mean?
The total store of energy in a system
What happens to w when energy leaves and enters a system (q =energy)?
Energy leaves the system = -w
Energy enters the system/work is done on the system = +w
What does expansion and non expansion work mean?
Expansion work: work arising from a change in the volume of a system
Nonexpansion work: work that doesn’t involve a change in volume of the system. (Alla material och mängder finns redan inuti kapseln)
What does free expansion mean?
No work done by a piston (Pex= 0 and w=0)
What happens when the external pressure on the piston is constant?
The system loses energy as work so work becomes -w and the equation is
w= -Pex*V
What happens when the piston moves in a reversed motion?
It’s often isothermal and V1= volume from the start and V2= volume at the end, we use the formula:
W= -nRT* ln(V2/V1)
What happens when w=0? In other words when no expansion or work is occurring. What happens when energy leaves and enter the system as heat?
U=q
Energy enters the system as heat= +q
Energy leaves the system as heat= -q
*What does adiabatic mean?
- what does diathermic mean?
What is specific heat capacities formula?
Cs= C/m (mass)
What is molar heat capacities formula?
Cm= C/n (moles)
What is a state function?
Give examples
A property that depends only on the current state of the system and is independent of how that state was prepared.
Ex) pressure, volume, temperature and density, internal energy.
What happens to the internal energy during an isothermal process?
U=0 so q+w=0
What letter is enthalpy denoted as and what other parts are included in its formula?
Is enthalpy a state function?
H= enthalpy.
Formula: H= U + P*V
It is a state function?
What happens to the enthalpy during constant pressure and no expansion work and what happens to the external pressure?
Pex=P
And
H=q
What is an endothermic and exothermic reaction and what is the value of H?
When does all this occur?
Exothermic: H<0
It absorbs little heat and releases a lot of it.
Endothermic: H>0
It absorbs a lot of heat and releases only a little of it.
It all occurs during constant pressure.
*What’s the formula for “enthalpy of vaporization”?
Hvap= Hm(vapor) - Hm(liquid)
What’s the formula for the enthalpy of fusion?
Hfus= Hm(liquid) - Hm(solid)
What’s the formula for the enthalpy freezing?
H reverse process = - H forward process
What’s the formula for enthalpy if sublimation and what does sublimation mean?
Hsub= Hm(vapor) - Hm(solid)
Or
Hsub= Hfus + Hvap
Sublimation= solid goes to vapor
What is Hess’s law?
The overall reaction H is the sum of the reaction enthalpies of the steps into which the reaction can be divided.
You balance the formula and then change H by how the formula is changed. Change its sign if the formula is reversed and then cross out the similar formulas.
What is a spontaneous change?
A reaction that can occur without needing an external influence
What is the definition for entropy?
Entropy= S
What is the formula for total entropy change?
Stot= S (change is system)+ S(change in the surroundings)
When is the entropy exothermic and endothermic?
Exothermic: S>0
Exothermic: S<0
When is the entropy spontaneous, no spontaneous and equilibrium?
Process is spontaneous: S>0
Process is non spontaneous: S<0
Process is at equilibrium: S=0
What happens to Gibbs free energy at constant T and P?
G=0
What happens to Gibbs free energy it is spontaneous, at equilibrium and no spontaneous?
Spontaneous: G < 0
Equilibrium: G=0
Non spontaneous: G >0
What does hydrophilic and hydrophobic mean?
Hydrophilic: attracts water
Hydrophobic: Repels water
What’s the like dissolves like rule?
Polar compounds dissolve each other and non polar compounds dissolve each other
What is the enthalpy of solution?
Hsol = HL (Lattice enthalpy) + Hhyd(enthalpy of hydration)
How is the equilibrium constant k affected by pressure?
Doesn’t change
What does the equilibrium constant depend on? And what happens when these factors increase on one of the sides?
Temperature and added/removed products/reactants (the concentration of products)
Add reactants: K will Increase
Add products: k will decrease
What is an acid and a base?
Acid = proton donor
Base= proton acceptor
***What is an bronsted acid and base? And what do they mean?
bronsted acid = proton donor (a substance that donates protons from a base in order for the reaction to occur)
Bronsted base = proton acceptor (a substance that accepts protons from an acid in order for the reaction to occur)
What is a weak/ strong acid?
Strong acid: all molecules are deprotonated in a solution (one normal arrow)
Weak acid: almost all molecules are deprotonated in a solution (two arrows)
What’s a strong/weak base?
Strong base: all molecules are protonated in a solution (one normal arrow)
Weak acid: almost all molecules are protonated in a solution (two arrows)
What is an Lewis acid/base?
Lewis acid: electron pair acceptor
Lewis base: electron pair donor
How do you write out the formula for the constant k?
K= [H3O+][OH-]/[H2O]
What does Kb and Ka mean and what does Pka and Pkb mean and equal?
Ka = acidity constant Kb = basicity constant
PKa= - log Ka PKb= - log Kb
How do you know when Kb and Ka is weak and what does it mean to the substance and it’s Pka and Pkb value?
Weak acid = small value of Ka = high value of Pka
Weak base = small value of Kb = high value of Pkb
The smaller the constant K is the harder it is for the base/acid to protolyse
What is coulombic force and when does it appear?
It’s the attraction between one positively cheated atom and one negatively charged atom. The force appears between the atoms.
What happens to the equilibrium constant when T is increased/decreased?
For an exothermic reaction where heat is released (H= negative), heat acts as a product.
If T increases -> product increases -> reaction moves to the left -> K decreases
If T decreases -> product decrease -> reaction moves to the right -> K increase
For an endothermic reaction where heat is absorbed (H= positive), heat acts as a reactant.
If T increases -> reactants increases -> reaction moves to the right -> K increase
If T decreases -> reactants decrease -> reaction moves to the right -> K decrease
