ap chem final study guide

Lavoisier, Law of Conservation of Matter

in a chemical reaction, matter is neither created nor destroyed

proust, law of constant composition

each pure chemical compound always has the same percentage composition of each element by mass

atomic theory, 4 principles

- each element and all matter is composed of atoms
- atoms are identical to one another in mass, and unique against all other elements
- atoms of one element can't be changed into atoms of another element
- chemical reactions are just rearrangements of actions (different combos!)

law of multiple proportions

if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers

cathode ray tube

Electrodes were stimulated to give off radiation -> these rays were consistent regardless of the cathode itself, and determined to be negatively charged; thus, the rays were concluded to be streams of negatively charged particles, aka electrons.

electron's charge to mass ratio

- (1.76 x 10^8 coulombs) per gram

millikan oil drop experiment

dropped oil drops which lost electrons as falling => gravity acted as downwards force, but the bottom plate repelled electron force; by determining when repulsion and gravity balanced, millikan discovers force and mass of an electron by applying charge to mass ratio

charge of an electron

Charge of an Electron: -1.6 * 10^-19 Coulombs

mass of an electron

9.11 * 10^-28 grams

alpha radiation

fast moving particles with a positive charge

beta radiation

fast moving high speed electrons with a negative charge

gamma radiation

high energy radiation without particles of charge

plum pudding model

electrons bathed like chocolate chips in a sea of positive charge

gold foil experiment

shone alpha particles at a gold foil => deflection and bounceback proved the existence of a dense positive center (nucleus!)

properties of a proton

Discovered by Rutherford, 1919

basic unit of positive charge

Magnitude: +1.6 * 10^-19 Coulombs

Mass of 1.67 * 10^-24 grams, 1836 times heavier than the electron

Relative Charge (+1)

Relative Mass in AMU: 1.0073

p

neutrons

Magnitude: 0 Coulombs

Mass of 1.67 * 10^-24 grams, same as proton

Relative Charge 0

Relative Mass in AMU: 1.0087

n

electrons

Magnitude: -1.6 * 10^-19 Coulombs

Mass of 9.109 * 10^-28 grams

Relative Charge (-1
)
Relative Mass in AMU: 5.486 * 10^-4
p

line spectra

colors consist of discrete wavelengths of light, each element is unique!

wave nature of light

all waves move thru a vacuum at the speed of light (3 x 10^ m/s)
- behave like sin/cosine functions; its periodic

wavelength and frequency relationship

- inversely proportional; long wavelengths mean lower frequency n vice versa

wavelength x frequency = speed of light
WAVELENGTH NM VERSUS SPEED OF LIGHT M

energy of light

energy is absorbed in quantum sizes

e = hv where v is the frequency.

h is planck's constant, 6.626 x 10^-34 joules per second

strength of diff. wavelengths

longer wavelengths mean weaker, shorter means stronger; red is weakest, purple is strongest

weakest to strongest wavelengths

radio, tv, microwave, infrared, uv, xray

note for prefixes

nano = -9
micro = -6
milli = -3
yk the rest

photoelectric effect

- when light hits a metal surface, the minimum amount of energy required to eject an electron differs
=> known as work function, the barrier to ejection

postulates of the bohr model

- electrons can only circulate in orbits of specific radii
- in a permitted orbit, energy isn't released so electrons don't collapse into the nucleus
- energy is emitted or absorbed when electrons jump from one orbit to another

ground vs excited state

ground state is when an electrion is in the lowest possible energy state, excited is when its in a higher energy state

energies of specific orbits

always negative because if n is infinite, it has no attraction the nucleus, making the energy zero
- the closer/more stable it is, the more negative it is.

principal energy levels

- big shells, hold max of n^2 orbitals and 2n^2 electrons
- starts at 1 starting from closest to the nucleus

sublevels/subshells

number of subslevels possible is equal to the value of n
- there's an s sublevel, p sublevel, d sublevel, etc.

orbitals

think of it more as subshell orientations
- s sublevel has 1 s orbital, p sublevel has 3 p orbitals, etc..

quantum numbers

n = prinicpal quantum number

l = angular momentum number, represents sublevel starting from 0 to n-1
-- 0 is the s orbital, n so on

ml = orientations of a specific orbital (-l to l)
-- -1 represents the first p orbital, 0 the second, etc...

spin quantum number, either + or - 0.5
-- positive is counterclockwise, negative is clockwise

pauli exclusion

no two electrons have the same 4 quantum numbers (you can't put a person in a person)

heisenberg uncertaintiy

position and momentum can't be known at the same time; the more you know about one the less you know about the other

hund's

electrons of the same energy go indiv. in each orbital before doubling up - like how u sit on the subway

aufbau

sideways christmas tree

exceptions to aufbau

- completely filled d for cu ag and au by unfilling s sublevel
- half filled d level for cr and mo is done by unfilling s sublevel

reading periodic table

d block starts on thrid shell
f block starts on fourth shell

spectroscopy

- microwave radiation represents molecular rotational disturbance
- infrared is molecular vibrational levels
- ultraviolet represent change in energy levels

electronic energy, vibration, and rotation << order from most energy to least energy required

beer lambert

lower concentration = lower absorbance, IE DILUTION = LESS ABSORBANCE

- if fingerprints are left, they cause light to scatter, making the light measurer think there's less light passing thru the sample and greater absorbance!

PERIOD VS GROUPS

PERIOD IS A ROW, GROUP IS A COLUMN

what are isotopes

Atoms of the same element with different numbers of neutrons

numbers of particles in atoms

- proton and electrons are always equal to the atomic number, but number of neutrons depend on the isotope mass minus the atomic number
-- i.e. uranium 235 has 143 (235 - 95) neutrons

radioactive decay

- unstable nucleus emits small particles to achieve stability
- emits electrons, neutrons, helium nucleus n positrons
- changes nuclear mass and charge!
- released in the form of xrays/gamma rays

mass spectrometry

molar mass is weighted avg of masses of all naturally occuring isotopes

groups of periodic table

- alkali metals, alkaline earth metals, transition metals, halogens, n noble gases respectively from left to right

elements liquid at STP

mercury and bromine

gases at STP

all noble gases

diatomic molecules

H, N, O, F, Cl, Br, I

BRINCLHOF

Polyatomic elements

sulfur and phosphorus

allotropes

elemet that has two or more distinct sets of chemical n phsyical properties like ozone and oxygen

effective nuclear charge

- core electrons shield valence electrons from getting full nuclear charge

effective charge = nuclear charge - screening constant, abides by coulomb's

trend: increases left to right, top to bottom

coulomb's

charge increases as nuclear charge increases n distance decreases

ionization energy

energy needed to remove an electron

trends = increases bottom to top, left to right

EXCEPT
- beryllium higher than boron because you're removing from full subshell
- same thing with nitrogen n oxygen

atomic radii

van der waals - shortest distance separating two nuclei during a colission is twice the radii of the atoms

trend: increases top to bottom, right to left

electron affinity

how much an atom wants an electron
- halogen has the most negative affinities meaning they WANT electrons
- noble gases have the most positive = DONT want electrons
- doesn't change much moving down a group

electronegativity

how much an atom can pull shared electrons toward itself, diagonal rule!

ionic radii

cations always smaller than neutral atoms of the same element, anions always larger due to increase in electrons and repulsion

boiling points

decreases top to bottom for metals, but increases top to bottom for nonmetals

PES

measures binding energy
- peak size proportional to number of electrons in a subshell
- electrons closer to core have higher energy, PAY ATTENTION TO THE AXIS.

properties of metals

- shiny luster, malleable, ductile, good heat and electricity conductors
- metallic character increases top to bottom, right to left

nonmetal properties

no luster, brittle, bad conductors of everything

metalloids

if metals n nonmetals had a mixed child, good for semiconductors

avogadro's

number of things in a mole => 6.02 * 10^23 particles/atoms/etc

amu

grams/mole

molecular vs empirical formula

actual number of compounds versus greatest common factor

chemical bonds

attraction between nucleus of one atom and electron of another

intramolecular - ionic

complete transfer of valence electrons
- en is greater than 2.0

intramolecular - covalent

similar electronegativites
- nonpolar covalent when less than 0.5, very equal sharing
- polar covalent when between 0.5 and 2; slightly more unequal sharing

intramolecular - metallic

when electrons free to move throughout a metallic lattice; attraction is the attraction between mobile electrons moving in a sea

strongest to weakest intramolecular forces

metallic, ionic, polar covalent, nonpolar covalent

intermolecular - dipdip

dipole-dipole; dipole of one molecule attractions to oppositely charged dipole of another; STRONGEST IMF

intermolecular - hydrogen

H and NOF
- positive end of hydrogen attracts to oxygen, nitrogen, or fluroine

london dispersion or van der waals

weakest forces, exist in all types of molcules
- momentarily induced dipole attraction due to uneven distribution

strongest to weakest imfs

hydrogen, dipole dipole, london dispersion attraction

boiling points by imfs

ionic compounds w ion to ion attraction, covalent compounds w hydrogen, polar covalent, and then nonpolar covalent

potential energy curves

if less than 0, its stable, if greater than 0 its unstable, and if there's no attraction, its zero.

bond energy

emergy required to break a bond, ENDOTHERMIC because you have to absorb energy

bond length

distance btwn atoms

single, double, triple bond

single is the weakest and longest, triple is strongest and shortest

lattice energy

energy require dto separate ions in an ionic bond

requirements for conductivity

charged particles that are MOBILE

substitutional vs interstitial

substituional = similar sizing, changes properties a lil

interstitial = smaller fits inside interstices of bigger, strengthens.

formal charge

valence electrons - number of assigned electrons

MINIMIZE for best lewis diagram

VSEPR Theory

- negative electrons repel each other
- bonds n lone pairs arrange themselves as far as possible to minimize repulsion

molecular versus electron geometry

- molecular geometry depends on number of lone pairs, electron just depends on total electron regions.

BOND polarity

electrons shared equally only when its a covalent bond between two identical atoms

free radicals

odd number of electrons

bond order

number of bonds divided by number of atoms bonded to

MOLECULAR polarity

- symmetrical means nonpolar
- nonsymmetrical are polar if the bonds are polar
- if central atom has more than one type of atom or nonbonding, its polar.

valence bond theory

covalent bonds are overlapping orbitals,

= sigma bonds are single bonds, overlap of two s orbitals
- pi bonds are overlaps of p orbitals
- doule bonds are one sigma one pi
- triple bonds are one sigma two pi

ELECTRON GEOMETRIES

two regions = linear
three regions = trigonal planar
four regions = tetrahedral
five regions = trigonal bipyramidal
six regions = octahedral

molecular shapes n angles - for two electron regions

always linear, 180 degree

molecular shapes n angles - for three electron regions

if there's no nonbonding, it's trigonal planar, 120
if there's one nonbonding, it's bent, 120

molecular shapes n angles - for four electron regions

if there's no nonbonding, its tetrahedral, 109.5

one nonbonding = trigonal pyramidal, 107

two nonbonding = bent, 104.5

molecular shapes - for five electron regions

no nonbonding = trigonal bypyramidal, 120 in plane and 90 in perpendicular to plane

one nonbonding is a seesaw, complex no one really knows ig

two nonbonding is a t, about 90

three nonbonding is linear, 180

molecular shapes - for six electron regions

zero nonbonding is octahedral, 90

one nonbonding is square pyramidal, 90

two nonbonding is square planar, 90

hybdrization (BY ELECTRON GEOMETRY)

sp for two regions, sp2 for three regions, sp3 for four regions, sp3d for five regions, sp3d2 for six regions

polar geometries

3 regions
- bent

4 regions
- trigonal pyramidal
- bent

5 regions
- seesaw
- t

6 regions
- square pyramidal

bond length pe graph

lowest point on graph represents length!