General Chemistry

Question 1

Atomic Mass vs Atomic Weight

Weight of a proton/neutron

Isotope abundance

Answer 1

Atomic mass- mass of single atom

Atomic weight - mass of one mole of an element

Weight of a proton/neutron = 1.66x10^24 g

More stable isotopes are found in greater abundance in nature (and have longer half lives)

Question 2

Rutherford model

Bohr model

Answer 2

Rutherford model - atom mostly empty space; positively charged center with negative elective orbiting randomly

Bohr model - electrons travel in fixed orbits at set distances (orbitals); energy level increases farther away from nucleus; quanta of energy radiated off an atom is equal to difference b/w 2 adjacent orbitals
L= nh E= -R(H)
2 pi n^2

R(H) = rydbergs constant = 2.18x10^-18J/electron

Question 3

Planck
planck’s constant

Emission & Absorption

Answer 3

Planck - first quantum theory - atoms radiated energy in small discrete bundles called quanta
E=hf where h = 6.6x10^-34 J•s

J =

Emission & absorption
E= hc = -R(H)((1/ni^2)-(1/nf^2))
Lambda

Question 4

Nonpolar covalent bond

Answer 4

When atoms have identical or nearly identical electronegativities and so share electron pairs with equal distribution of electrons

Question 5

Ionic Bonds

Answer 5

High melting point
High boiling point
Dissolve readily in water and other polar solvents
In aquesous state, are GOOD conductors of electricity
Form crystalline lattice in solid state - more attractive forces

Question 6

Covalent bonds

Answer 6

Low melting and boiling points
Don’t break down into ions –> POOR conductors of electricity
properties - Bond length, bond energy, polarity

Question 7

Polar covalent bonds

Answer 7

difference in electronegativities (0.5 - 1.7) causes separation of charge across the bond - but not enough to form ionic bond
has partial negative and partial positive charges and dipole moment (p=qd) p is in Coloumb-meters

Question 8

Coordinate Covalent bond

Answer 8

both of the shared electrons originate on the same atom

-meaning lone pair of one atom attacked another atom with unhybridized p-orbital to form a bond

Question 9

Lewis Acid
Lewis Base
Formal charge

Answer 9

Lewis Acid - accepts lone pair of electrons
Lewis Base - donates pair of electrons
Formal charge = V = N(nonbonding electrons) - (0.5*N(bonding electrons))

Question 10

Formal charge vs oxidation state

Answer 10

Formal charge underestimates effect of electronegativity and oxidation state overestimates effect of electronegativity

Question 11

Gram equivalent weight

Answer 11

Gram equivalent weight = molar mass/n
where n is number of particles of interest produced or consumed per molecule of the compound in the reaction
equivalents = mass of compound/gram equivalent weight

Question 12

Normality (N)

Answer 12

normality = equivalents/L

in 2 N solution of H2CO3, the molarity of H2CO3 is ).5 M because H2CO3 has 2 protons/hydrogens

Question 13

law of constant composition

Empirical vs molecular formula

Percent composition

Answer 13

any pure sample of a given compound will contain the same elements in an identical mass ratio
H2O molecules will always have 2 hydrogen atoms for every one oxygen atom

empirical - simplest whole number ratio of elements
molecular - exact number of atoms of each element

percent composition - of an element (by mass) - is percent of specific compound that is made up of a given element

Question 14

Combination RX (reaction)

Decomposition RX

Combustion RX

Single -displacement RX

Double - Displacement RX/metathesis

Neutralization RX

Answer 14

Combination RX (reaction) - two or MORE reactants form one product

Decomposition RX - single reactant breaks down into one or more products; usually as a result of heating, high frequency radiation, electrolysis

Combustion RX - involves a FUEL, usually a hydrocarbon, and an OXIDANT(normally oxygen); forms carbon dioxide and water!!!

Single -displacement RX - atom/ion is replaced by an atom or ion of another element

Metathesis RX/double displacement - occurs when one of the products is removed from solution as a precipitate or gas when two of the original species combine to form a weak electrolyte that remains undissociated in solution

Neutralization RX - specific double displacementl acid reacts with base to produce a salt and usually water

Question 15

Percent yield

Answer 15

percent yield = (actual yield/theoretical yield) *100%

Question 16

Ionic compounds naming

Answer 16

Pg 135 gen chem

Question 17

Solid vs aqueous ionic compounds

Answer 17

solid - lattice arrangement so POOR conductors of electricity
in aqueous solution - ion-dipole interactions between ionic components and water molecules exist - so solution of ions can conduct electricity

Question 18

electrolytes -

Answer 18

solutes that enable solutions to carry currents
~pure water is a poor conductor
` strong electrolytes are ionic compounds with HIGHLY polar covalent bonds that dissociate easily when dissolved (EXAMPLES - NaCl and KI)
weak electrolytes - hydrolyzes/ionizes incompletely (EXAMPLES - Hg2I2, acetic acid and other weak acids, ammonia, other weak bases) NONelectrolytes - dont ionize in water at all - like nonpolar gases and organic compounds (O2, CO2, glucose)

Question 19

Intermediate

rate-determining step

collision theory of chemical kinetics

activation energy

reaction rate

Answer 19

Intermediate

rate-determining step - slowest step; prevents rest of RX from occurring

collision theory of chemical kinetics - rate of RX is proportional to the number of collisions per second b/w the reacting molecules

activation energy - minimum energy of collision necessary for a RX to take place

reaction rate = Z x f

Z = total number of collisions occurring per second
f = fraction of collisions that are effective
Or use the Arrhenius equation to find reaction rate where k = A* e^(-Ea/RT) where k is rate constant, R is ideal gas constant, R is activation energy, T is temp in kelvins
reaction rate = Molarity/second
rate = k[A]^x * [B]^y

Question 20

Transition state vs reaction intermediate

Factors that affect reaction rate

Answer 20

transition state - theoretical construct that exist at point of maximum energy
reaction intermediate - distinct molecules with finite lifetimes

factors that affect reaction rate - reaction concentrations, temperature, medium, catalysts (homogenous vs heterogenous catalysis)

Question 21

Keq for reversible reaction

reaction order vs equilibrium constant expression

Answer 21

for reversible reaction, Keq = k (forward reaction)/ k (of reverse reaction)
notes on Pg 166 Gen chem

Question 22

zero-order
first order
second order RX

Answer 22

zero-order
``````` rate = k
first order
`````` rate = k[A]
second order RX
```````rate = k[A]^2

Question 23

what does it mean for enzyme to be saturated?

Answer 23

When there is too much substrate, it will attach to all the enzyme and will saturate the enzyme, thereby reaching the maximal turnover rate of the reaction. basically enzymes can only make the reaction go so fast to a point