UWorld missed concepts

Why is boiling point influenced by hydrogen bonding

structures with less intermolecular forces have lower boiling points bc less energy is required to overcome the attractions between molecules during the phase change from a liquid state to a gas state

Describe cross-sectional studies

they are observational; data is gathered at one point in time and can determine prevalence of an outcome in a population

What type of bonds are broken during melting

covalent bonds are not broken during melting; intermolecular forces are broken during melting

what is bipolar disorder characterized by

mania and depressive episodes

what is borderline personality disorder characterized by

mania

what does the rate law reaction relate

the rate of a rxn to the concentration of each reactant

what order is a reaction rate if doubling the reactant concentration doubles the reaction rate

first order

what order is a reaction rate if doubling the reactant concentration quadruples the reaction rate

second order

how do you find the overall order of a rate law reaction

sum of the reaction orders of each rate influencing reagent

what is bond enthalpy/ bond dissociation energy

the amount of energy needed to break 1 mole of a bond between 2 atoms in the gas phase at 298 K

how do you find the bond enthalpy

the sum of the bond enthalpy of the bonds broken + the sum of the bond enthalpy of the bonds formed

what is the specific heat capacity reported in

J/g*C

what is specific heat capacity

the amount of heat needed to raise the temperature of 1 gram of a substance by 1 C

fusion

solid to liquid

freezing

liquid to solid

vaporization

liquid to gas

sublimation

solid to gas

deposition

gas to solid

triple point

point in phase diagram where all 3 phases exist

supercritical fluid

density of gas is the same density of liquid; no distinction between the two phases

anything transforming to a gas is a what kind of reaction

endothermic

anything transforming to a solid is what kind of reaction

exothermic

what does spontaneous mean in a reaction

it is irreversible

what does enthalpy focus on

the beginning of the reaction

what does entropy focus on

the end result of the reaction; does the end result look more or less ordered

what does a positive entropy mean

the free change is more random

what does a negative entropy mean

more order

what does a positive enthalpy mean

the reaction is endothermic

what does a negative enthalpy mean

the reaction is exothermic

when enthalpy and entropy are both positive

the reaction will be spontaneous at high temperatures

when enthalpy is positive and entropy is negative

the reaction is non spontaneous at all temperatures

when enthalpy is negative and entropy is positive

the reaction is spontaneous at all times

when enthalpy is negative and entropy is negative

the reaction is spontaneous at low temperatures

entropy (s)

measure of system's thermal energy per unit temperature that's unavailable for doing work

why is gibbs free energy helpful

it allows you to determine if a reaction will be spontaneous or not

what two things are needed to find gibbs free energy

enthalpy and entropy

if gibbs free energy is negative

the reaction is spontaneous

if gibbs free energy is positive

the reaction is non spontaneous

if gibbs free energy \= 0

the reaction is at equilibrium

ions with a greater charge have

more negative standard entropies

compounds with greater molar mass have

more positive entropy

what is exergonic interchangeable with

spontaneity

what is endergonic interchangeable with

non spontaneous

forming a bond is

exothermic

breaking a bond is

endothermic

a positive enthalpy means

endothermic

a negative enthalpy means

exothermic

a positive gibbs free energy means

non spontaneous

a negative gibbs free energy means

spontaneous

state functions

the intrinsic property of a thermodynamic system that depends only on the state system

types of state functions

enthalpy, temperature, pressure, density, volume, internal energy, gibbs free energy, entropy

process functions

describe the pathway from one equilibrium state to another

types of process functions

work and heat

what does electronegativity depend on

the distance of the valence electrons from the nucleus and on how well the core electrons shield the valence electrons from the nucleus (effective nuclear charge)

what is the ionization energy influenced by

the effective nuclear charge of the atom

what happens to the ionization energy if the Zeff is increased

it increases

what does the effective nuclear charge (Zeff) depend on

the number of protons in the nucleus and the number of core electrons providing charge screening around the nucleus

what happens to the effective nuclear charge as the number of electrons increase

it decreases

what happens to the frequency and energy values as wavelength values increase

they decrease

STP

at 1C and 1 atm, 1 mole of gas occupies a volume of 22.4L

Calorimetry

measures the temperature as a rxn progresses; change of temperature

Charles law

increase in V corresponds to an increase in T

Gay-Lussac’s Law

increase in pressure corresponds to increase in T

avogadro’s law

increase in volume corresponds to increase in number of moles

higher wavelength values mean

lower frequency and energy

latent heat of vaporization describes

the amount of heat a substance must absorb to transition from the liquid to the gas phase

Keq is related to Gibbs free energy by

G = -RT lnKeq; if ln(Keq) is positive, Gibbs free energy is negative

What ion transport occurs at the nodes of Ranvier

Na+

Molar concentration

defined as the moles of solute per liter of solution

density

mass/volume

ionic radii tend to decrease in size across

a period left to right and increase moving down a group

in an isoelectronic series, ionic radii decrease

as the atomic number increases

parts per million (ppm)

(mass of solute/mass of solution) x 10^6

During cation formation, electrons are lost from

the highest-energy filled shell/subshell first & added to the lowest-energy unfilled shell/subshell first

mass percent (%m/m) is defined as

the component mass divided by the total mass of the formula unit of mixture expressed as a percentage

What is needed to calculate the mass percent

mass of solute and solvent, and density of the liquid

An atom in its elemental state is neutral with equal number of

protons and neutrons in the nucleus

How can number of neutrons be found

by subtracting atomic number from the mass number

how does an atom in its elemental, neutral state acquire a net charge of +1 or -1

by losing or gaining an electron during ionization

What are the representative elements

groups 1,2, 13-18

when would an electron temporarily jump to a higher energy orbital

the electron achieves an excited state by absorbing energy equal to the energy difference between the two levels

Negative controls

experiment change is not expected to be seen

positive controls

experiment change is expected

when does predomination protonation of a functional group change

when the pH crosses the pka value

what does it mean if the pKA is higher than given pH environment

the functional group will less likely be deprotonated

hydroxyls, thiols, and amines can serve as

nucleophiles to form covalent bonds in nucleophillic substitution or addn reactions during covalent catalysis

how is enzymatic function maintained

by noncovalent interactions in the tertiary and secondary structures of proteins

how do antibodies generally bind their targets

in noncovalent protein-protein interactions

how are protein levels in a cell controlled

by expression and degradation rates

how are degradation rates of proteins controlled

by targeting secretory proteins to the lysosome and cytosolic proteins to the proteasome using ubiquitin tags

what kind of band would form on a reducing gel if the protein is a homomultimer

only one bamd

what are the branched chain amino acids

leucine, isoleucine, valine

what happens to proteins that adopt nonnative conformations

they are forced to expose more hydrophobic residues to aqueous environments; they tend to aggregate to minimize exposure due to the hydrophobic effect and leads to precipitation

what do all beta-sheets participate in

backbone hydrogen bonds

what is the average molecular weight of an amino acid

110Da

At concentrations above Ksp, the ions

combine and precipitate

sigma bonds are

more stable than pi bonds

sigma bonds have

a higher dissociation energy

what can stronger lewis bases do

displace weaker lewis bases as ligands within a coordination complex

lone pair e- atoms with lower electronegativity tend

to be stronger Lewis bases than those with a higher electronegativity