Gen Chem Flashcards
What are isotopes?
Same elements with the same atomic number (protons) and chemical properties but different number of neutrons (mass number)
What do valence electrons determine?
Chemical properties of that molecule
VE’s are also the most easily removed and most available for bonding
Electrons: lowest mass
Protons: moderate mass
Neutrons: most mass
Atomic mass vs. atomic weight?
Atomic mass: roughly equal to the mass number in amu
Atomic weight: weighted average of isotopes (as most all elements exist as isotopes)
What is important in the Bohr model about electron energy levels?
As electrons rise in energy level they absorb light, become excited, have higher potential, and become more distant from the nucleus
If enough energy is transferred electrons can move to an excited state (beyond ground state of n=1)
Excitation is brief and the return to ground state is associated w/ photon emission
Instead of the Bohr model where do electrons really exist?
In orbitals or regions in space b/c of electron-electron repulsion
What is the Heisenberg Uncertainty principle?
It is impossible to determine both the momentum and position of an electron
What are the quantum numbers and what do they describe?
They describe the location of an electron
Principal Quantum Number (first number)
- denoted as n
- larger the value indicates the higher the energy level
and radius
- corresponds to the row or period
Azimuthal Quantum number (second number)
- denoted as ℓ
- describes the shape and number of subshells
- 0: s subshell
- 1: p subshell
- 2: d subshell
- 3: f subshell
- larger the value the greater the energy level
Next is Magnetic Quantum Number (mℓ) then Spin Quantum Number (ms)
What is electron configuration? Aufbau Principle? Hund Principle? Pauli Princple?
Ex: 1s2, 2s2, 2p4 is electron configuration for O
If anion: add another electron so 2p4 becomes 2p5, if cation:
Aufbau: electrons fill from low to high energy levels and fill shells fill completely before filling next energy level
Hund: electrons fill all half shells first then double up (this minimizes repulsion), this makes it so half and fully filled orbitals have lower energy
Pauli: electrons have opposite spins
Paramagnetic vs. diamagnetic?
Paramagnetic: means has unpaired electrons, is attracted to magnets, parallel spin alignment and magnetic field lines bend toward material
Diamagnetic: means all paired electrons, is repelled by magnets, anti-parallel spin alignment and magnetic field lines bend away from material
Periods/groups correspond to rows/columns? Valence electrons?
Periods are rows
Groups are columns (which corresponds to # of VE’s)
What is the periodic notation?
Top is atomic number next is the element and bottom is the atomic weight
Metals vs. nonmetals vs. metalloids characteristics?
Metals: left side of periodic table
- low electronegativity
- low charge
- large atomic radius
- small ionic radius
- LOW IONIZATION ENERGY
- GOOD CONDUCTOR
Nonmetals: right side of periodic table
- HIGH IONIZATION ENERGY
- high electronegativity
- POOR CONDUCTOR
Metalloids: b/w transition metals and right side
- semi-metal so mixed characteristics
How do you determine the smallest ionic radius in an isoelectric series?
Vs. atomic radius
Just know that cation = smallest and anions = biggest b/c isoelectric so only that (+) or (-) matters
Atomic radius is determined by periodic table
What is Zeff and where is it largest of periodic table?
Effective nuclear charge or the pull of valence electrons to the nucleus
It increases from left to right across a period because more valence electrons = more attraction with nucleus
What do the noble gases represent?
The ideal valence electron configuration, most stable/inert/nonreactive
What is the atomic radius periodic table trend?
Atomic radius is highest in the bottom left corner of the periodic table
Left because a lower Zeff holds valence electrons less tightly
Bottom because shells are added resulting in valence electrons being farther away
What is the ionization energy periodic table trend?
Ionization energy is highest in the top right corner of the periodic table
It is the energy required to remove an electron from the nucleus so the closer it is to the nucleus the harder it is to remove
What is the electronegativity periodic table trend?
Electronegativity is highest in the top right corner of the periodic table
It is a measure of the attractive force to an electron, how well it can tolerate a (-) charge
What group are alkali metals/alkaline earth metals/halogens/noble gas located in?
Transition metals?
Alkali metals: Group 1 (reactive)
Alkaline earth metals: Group 2 (reactive)
Halogens: Group 17 (reactive with G1,2 metals)
Noble Gas: Group 18 (inert, high IE, no electronegativity, low BP)
Transition metals: the stuff in the middle (high BP and MP, good conductors)
Ionic bond vs. covalent bond characteristics?
Ionic bonds:
- significantly different electronegativities (metal and
non-metal)
- higher BP and MP than covalent because of
electrostatic attraction
- readily dissolve in water and polar solvents
- aqueous: good conductors
- solid: form a crystalline lattice
Covalent:
- similar electronegativities
What are bond length trends?
C≡C is shortest and strongest
C-C is longest and weakest
Bond length increases w/ atomic radii so larger atomic radii = weaker bond
What are bond energy trends?
Energy required to break a bond so higher bond energy = stronger bond
What is polarity? In bonding?
Refers to the electronegativity difference b/w atoms that creates a dipole with positive end at less electronegative atom
Polar bonds: unequal sharing of electrons from electronegativity difference
Non-Polar bonds: equal sharing of electrons or diatomic (O2, N2, etc.)
What are coordinate bonds? Coordination number? Usually a lewis acid/base?
Bonds where both pairs of bonding electrons come from the same atom, USUALLY COORDINATE COVALENT
Coordination number: number of atoms bound to a central atom
Central atom is usually lewis acid and ligands are usually lewis base
How do you calculate formal charge?
FC = VE - sticks - dots
sticks being number and dots being individual electrons in LP’s
What is resonance?
Molecular structures w/ the same arrangement of atoms but differ in the placement of electrons
Exist as hybrid structures with electron delocalization
The more stable a resonance structure the more it contributes to the hybrid structure
What three things can determine stability of a molecule?
1) lower FC
2) less separation of opposite charges
3) (-) charge on more electronegative atom
VSEPR Shit…
2 electron clouds: linear (180)
3 electron clouds: trigonal planar (120)
w/ a LP: bent
4 electron clouds: tetrahedral
w/ a LP: trigonal pyramidal
5 electron clouds: trigonal bipyramidal
Single/sigma bond vs. double/pi bond?
Sigma bonds have head to head overlap and free rotation
Double bonds are made up of a sigma bond and a pi bond that makes it have side to side or parallel overlap and no free rotation
What are the three types of IMF’s?
1) London Dispersion Forces
- short-lived attractive/repulsive interactions by shifting
dipoles
- everything has these
2) Dipole-Dipole
- when polar molecules orient such that the partial
negative regions are near the partial positive region of
another molecule
3) H-Bonding
- Partial positive H interacts w/ partial negative (F, O, N)
that is nearby
- INCREASES BOILING POINT
IMF’s when summed together can be quite impressive
How many particles are in a mole?
6.022x10^23
What are equivalents?
The number of mols of the interested substance does one mole of a given compound produce
= mass of compound (in grams) / gram equivalent weight
What is gram equivalent weight?
the amount of compound, in grams, that produces one equivalent of a particle
= molar mass/n n: # of particles produced/consumed
What is normality?
A measure of concentration using equivalents (equivalents / L)
Molarity = normality/n
Empirical vs. molecular formula?
Empirical formula: Simplest/smallest whole-number ratio of elements in compound (CH)
Molecular formula: Exact number of atoms of each element in the compound (C6H6)
What is a combination reaction vs. decomposition reaction?
Combination: Two or more reactants forming one product
Decomposition: A single reactant breaking down into two or more products
What is a combustion reaction?
Involves the formation of CO2 and H2O from a fuel (hydrocarbon) and an oxidant (O)
What is a single displacement vs. double displacement reaction?
Single displacement: Atom in a compound is replaced by an atom of another element
Ex: Cu + AgNO3 –> Ag + CuNO3
Double Displacement: elements from two different compounds swap places w/ each other to form two new compounds
Ex: CaCl2 + AgNO3 –> Ca(NO3) + AgCl
What is a neutralization reaction?
A type of double displacement reaction where an acid and a base react to produce water and a salt
What is a redox reaction? Disproportionation? Oxidation state rules?
A reaction that involves a change in oxidation state
Dispro: when both oxidation and reduction happen to atoms of the same element
Element by itself: 0
Neutral compound: sum of oxidation numbers is 0
Ionic: sum of oxidation numbers is the charge
Group 1: +1
Group 2: +2
Group 17: -1 (+1 w/ O)
H: +1 (w/ nonmetal) -1 (w/ metal)
F: -1
O: -2 (-1 w/ H2O2)
What does collision theory state?
That rate is proportional to the number of collisions of sufficient KE to overcome the Ea
What does transition state theory state?
That when molecules w/ sufficient Ea collide they form a transition state (greatest free energy) that then dissociates into product
ΔG is b/w?
Free energy of products and reactants
+ΔG: endergonic, energy absorbed
-ΔG: exergonic, energy released
Plot it on reaction coordinate diagram to see
Forward and reverse reaction have same ΔG but possibly different Ea
What factors can affect reaction rate?
- reactant concentration (greater concentration = greater rate)
- temperature (greater temp = greater rate)
- reaction medium
- catalysts
What are functions of catalysts?
- increase frequency of collisions
- change orientation for more effective collisions
- STABILIZE TRANSITION STATE INTERMEDIATE
- LOWER Ea (FORWARD AND REVERSE) WITH NO CHANGE IN ΔG OR Keq
- Not consumed
What is the rate law equation? How do you determine reaction orders? What are the reaction orders?
Rate = k[A]^x[B]^y
x,y are the orders of the reaction
k = reaction rate coefficient
1) identify pair of trials where concentration of one reactant changes and all others are held constant
- to find rate order for [A] find where [B] is same but [A]
changes
2) identify order of reaction
3) replace exponents to create rate law
Zero Order: independent of concentration changes
First Order: directly proportional to one reactant
Second Order: proportional to the square of a single reactant
Overall: sum of individual orders
What is bicarbonate buffer reaction?
CO2 + H2O <> H2CO3 <> H+ + HCO3-
H2CO3: carbonic acid
HCO3-: bicarbonate
What is Keq?
Equilibrium constant
Keq = [products]/[reactants]
exponents = stoich coefficients
@equilibrium and given temp
Exclude solids, liquids (H2O)
Greater Keq indicates -ΔG, spontaneous reaction, equilibrium favors forward reaction
What is Le Chatelier’s Principle? Pressure effect? Temperature effect?
Systems always react in a direction to restore equilibrium
Law of Mass Action: buildup of reactants one side will push the forward reaction towards production formation
Pressure: when pressure is increased reaction will shift towards side w/ less moles of gas
Temperature: affects Keq, ΔH>0 (endothermic) heat is reactant, ΔH<0 (exothermic) heat is product
What is the kinetic vs. thermodynamic product?
Kinetic product: forms faster but is less stable, found in lower temps (less free energy added), determined by Ea, irreversible
Thermodynamic product: forms slower but is more stable, found in higher temps (more free energy added), determined by ΔG, reversible
- stability: measured in heat of combustion
What is a state function?
It describes system in equilibirum
What is a process function?
It describes pathways b/w equilibrium states
Identify points on a phase diagram
Refer to notes (Gen Chem Ch. 7)
What is enthalpy? Equation? Exothermic? Endothermic?
ΔHrxn = Hproducts - Hreactants
(+)ΔH = endothermic, breaking bonds (-)ΔH = exothermic, forming bonds
ΔHrxn = ΔHbonds broken - ΔHbonds formed
What is entropy?
The measure of the dispersal of energy (how spread out it is) or measure of disorder
Increased entropy is increased disorder
What is Gibbs Free Energy? Equation? Exergonic? Endergonic?
ΔG = ΔH - TΔS
(-)ΔG = spontaneous (+)ΔG = non-spontaneous ΔG = 0 = equilibrium
Exergonic on reaction diagram is free energy of products is lower
Ea = Etx state - Ereactants
When ΔH and ΔS have same signs then ΔG is dependent on temperature
- if both (+) then spontaneous at high temps
- if both (-) then spontaneous at low temps
(+)H and (-)S = non-spontaneous
(-)H and (+)S = spontaneous
What is STP? Gas at STP?
273K and 1 atm
Any gas at STP has a volume of 22.4L/mol
Or one mole of gas occupies 22.4L of volume
What is barometer?
Atmospheric (external pressure) applies on outside, opposing force of weight applies on inside
When atmospheric pressure is greater the fluid rises
What is an ideal gas? Assumptions? Equation?
1) molecules have no IMF’s
2) molecules have elastic collisions
3) molecules occupy negligible volume
PV = nRT
pressure, volume, number of moles, constant, temperature
Is N2 stable?
Yes, very inert because N triple bonds
What is the combined gas law? Boyle’s law? Charle’s law? Gay-Lussac’s law?
Combined: P1V1/T1 = P2V2/T2
Boyle’s: pressure is proportional to inverse of volume, P1V1 = P2V2
Charle’s: volume is proportional to temperature, V1/T1 = V2/T2
Gay-Lussac’s: pressure is proportional to temperature P1/T1 = P2/T2
Avogadro: T and P are constant when volume is proportional to n mols
What are gas partial pressures?
Indicates the total amount it contributes overall
Ptotal = P (of A) + P (of B)
What is a solution? Solute? Solvent?
A homogenous mixture of two or more substances that combine to a liquid phase
Solute: substance that is dissolved in the…
Solvent:
What is solubility? Equation? Ksp?
The max amount of solute that can be dissolved in a solvent at a given temp.
If solute is beyond the Ksp, or saturation, it will precipitate and form a solid
Ksp = [a x prodcuts]^a / [b x reactants]^b
- a,b = stoich coefficients, raised to power and multiplied by
- solids and pure liquids are not included
- only gases and aqueous are included
Common ion effect
What is the dilution equation?
M1V1 = M2V2
What will dissolve in what?
Like dissolves like
Polar solvent will dissolve polar solute
What are colligative properties? Examples?
Properties dependent of dissolved particles and not chemical identity
BP: The temp where vapor pressure = external pressure
- so vacuum lowers BP
- intermolecular
Vapor pressure: increase solute causes a lower vapor pressure of solvent so higher temp needed for BP
Freezing point: increased solute results in a lower (more cold) freezing point b/c particles interfere in lattice structure
- intermolecular
What is an Arrhenius base/acid?
Acid: dissociates to form excess H+ in solution
Base: dissociates to form excess OH- in solution
What is a Bronsted-Lowry acid/base?
Acid: H+ donor
Base: H+ acceptor
What is a Lewis acid/base?
Acid: electron pair acceptor
Base: electron pair donor
What are amphoteric species?
Can behave as both an acid and a base, H2O for example
What is the autoionization of water?
H20 + H2O <> H3O + OH
Water can react with itself
Kw = 1x10^-14
pH and pOH equations?
pH = -log[H+] -log 10^-7 =7
pOH = -log[OH-}
pH + pOH = 14
What are the strong acids?
Completely dissociate in solution
H2SO4 HI HBr HNO3 HCl HClO4
So I brought no clean clothes
What are strong bases?
NaOH
KOH
other group 1 metals
Ka, Kb, Kw?
(Ka)(Kb) = Kw
[products]/[reactants]
Lower Ka = weaker acid
Lower pKa = stronger acid
Compare Ka and Kb can figure out if acid or base
What are titrations? Equivalence points? Indicators? Polyprotic meaning?
Titration: used to determine the concentration of a known reactant in solution
- add titrant to titrand until reaching an equivalence
point (steep part) which indicates acid/base
equivalents are equal
- flat parts indicate the pKa’s
Number of equivalence points equals the number of steep parts
Blue = base Red = acid
Polyprotic: means the molecule can lose multiple protons (has multiple H’s) so will also have multiple equivalence points
What are buffers? Equation?
pKa = +/- 1 pH unit
A mixture of a weak acid its salt (conjugate base and cation)
A mixture of a weak base and its salt (conjugate acid and anion)
These mixtures are able to resist drastic changes in pH
pH = pKa + log ([base]/[acid])
OILRIG? Oxidizing agent? Reducing agent?
Oxidation is loss of electrons
Reduction is gain of electrons
Oxidizing agent: itself is reduced and causes another thing to get oxidized
Reducing agent: itself is oxidized and causes another thing to get reduced
What is a spectator ion?
An ion on both sides of the reaction in the same and therefore doesn’t take part in the reaction
Electrochemical cells.. where does oxidation/reduction occur at?
Reduction @ cathode
Oxidation @ anode
Electrons move anode –> cathode
Galvanic/Voltaic vs. electrolytic cells?
Ecell = Ecathode - Eanode
Galvanic: spontaneous reactions so has a (+)Ecell
- anode is negative and cathode is positive
Electrolytic: non-spontaneous reactions so has a (-) Ecell
- anode is positive and cathode is negative
What are reduction potentials? Where do electrons appear in half reactions for red/ox?
Refers to the likelihood a compound is to be reduced (Ered)
(+) E red: spontaneous reduction
(-) E red: non-spontaneous reduction
When working with reduction potentials you sum them but may need to flip sign of one of the half reactions so they’re both reduction
Ered = oxidizing agent - reducing agent
Reduction: electrons are included with the reactaints
Oxidation: electrons are included with the products
What is a reference electrode?
It contains known electrical potential and ion concentration
What energy level do lost electrons get removed from?
The highest energy level so if there was a partial 3d orbital the 4s electrons would be removed
