Studied by 2 peoplewhat are the nuclei of atoms made up of?
protons and neutrons
electrons “float” around outside the nueclus
what are valence electrons? what are the energy levels?
electrons on the outermost electron shell
there are 7 energy levels each with orbitals that contain 2 electrons
s: 2 electrons (1 sub-shell)
p: 6 electrons (3 sub-shells)
d: 10 electrons (5 sub-shells)
f: 14 electrons (7 sub-shells)
Hund’s rule
each orbital needs one upspin and one downspin before any orbital gets two spins
electron config order
1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6, 5s2, 4d10, 5p6, 6s2, 4f14
noble gas config
(closest noble gas) + rest of electron config
do positive ions gain or loose electrons?
positive: looses electrons
negative: gains electrons
isoelectronic
two species have the same electron config
mass number of an element
#protons + #neutrons
charge of an atom
#protons - #electrons
atomic number
#protons
isotope
same element (#protons), different mass (#neutrons)
ion
same #protons and #neutrons, different charge (#electrons)
finding average atomic mass
(mass of isotope 1)*(abundance) + (mass of isotope 2)*(abundance)
for electron to get closer to the nucleus it must,
loose energy (emission)
for electron to get further from the nucleus it must,
gain energy (absorbtion)
True or False: all colors of light travel at the same speed
true
which colors of light have the most energy?
high to low (aka short to long wavelengths) →
red
orange
yellow
green
blue
purple
alkali metals
col 1, very reactive
alkaline earth metals
col 2
halogens
col 17, very reactive
noble gases
col 18, very un-reactive
ionization energy def & trend
def: energy needed to remove a valence electron from a neutral atom
trend: ↗
electron affinity def & trend
def: energy needed to add a valence electron to a neutral atom
trend: ↗
electronegativity def & trend
def: energy tendency of an atom to attract a valence electron
trend: ↗
non-metal reactivity trend
explanation: non-metals want to gain electrons, so the trend is the opposite of the atomic radius trend because the smaller the radius the easier it is to add electrons
trend: ↗
atomic radius def & trend
def: distance between nucleus and valence electrons (if there is two atoms, divide distance between the nuclei by 2)
trend: ↙
metal reactivity trend
explanation: metals want to loose electrons, so the trend is the same as atomic radius because the bigger the radius the easier it is to remove electrons
trend: ↙
coulombs law
opposite charges attract
what are the two main factors that cause atoms to have a strong attractive force?
smaller radius
lots of protons
ionic bond
metal and non-metal
“stealing electrons”
non-metal steals electrons from the metal
covalent bond
2 non-metals
“sharing electrons”
metallic bond
2 metals
“sea of electrons”
create lattice structures
electrons can move freely which makes these structures good conductors
cation
positive ions
loose electrons
anions
negative ions
gain electrons
transition metals
don’t have full electron shell in level 3 so they can loose more than just valence electrons
lattice energy
energy released when a lattice structure is created
writing ionic compounds
must be neutral:
take charges of each element
the coeff is the same as the other element’s charge
formal charge
the charge an atom would have if bond was broken evenly
to find it: valence electrons - electrons on atom
VESPR structure
electrons pairs repel, so they must be as far apart as possible
polar compounds
happen when one of the molecules is super electronegative which gives the compound a slightly negative overall charge
naming compounds
covalent: first element no prefix, -ide suffix, second element prefix for coeff
ionic: no prefixes at all, -ide suffix, use roman numerals for transition metals
intramolecular forces
ionic, covalent, metallic
intermolecular
dipole-dipole, london dispersion, hydrogen, ion-dipole
london dispersion
2+ non-polar molecules: electron temporarily disperse, happens between covalent molecules
dipole-dipole
2+ polar molecules
hydrogen bonding
hydrogen molecule bonded with N,O or F
ion-dipole
ion bonded with a polar molecule
stronger IMF creates a
higher boiling point
heavier compounds also have a higher boiling point
mixtures
can be physically separated
homogenous: can’t tell the components apart
heterogenous: can tell components apart
pure substances
can’t be physically separated
compound: can be chemically decomposed
element: can’t be chemically decomposed
physical seperation
breaks IMFs
chemical seperation
breaks compounds
synthesis
2+ substances combine into one product
(A+B→ AB)
decomposition
substance breaks into 2+ products
(AB → A + B)
single replacement
1 element switches with another
(AB + C → A + BC)
double replacement
positive and negative ions of reactants are switched
(AB + CD → CB + AD)
combustion
fast reactions that produce co2 and water
(fuel + O2 → CO2 + H2O)
BOOOOOOOOOOOOM
scientific notation
#>1: move decimal left for a POSITIVE power
#<1: move decimal right for a NEGATIVE power
Avogadros #
6.02 * 10^23
chemical reactions
changes in valence electrons
nuclear reactions
changes in the nucleus
transmutation
change in protons (diff element) or change in neutrons (diff isotope)
radioactivity
decomposition of a nucleus to form a new one
half life
the time it takes for half of the sample to die
ionizing radiation
release of energy that allows unstable nucleus to become stable
alpha decay
releases an alpha particle, makes smaller atom
beta decay
releases an electron
happens when there are too many neutrons
positron emission
releases a positron
happens when too many protons
gamma decay
releases pure energy
happens when there is too much energy
fusion
nuclear process that combines smaller elements into larger ones by adding alpha particles (He)
fission
releases energy by bombarding compounds with neutrons till they split apart
equation to find energy released during fission
e = mc^2
where m = mass defect (predicted mass - actual mass)
c = speed of light
half life equation
n(t) = N(1/2)^(t/t1/2)
where N is the og sample
t is time
and t 1/2 is alf life
percent composition
by mass not molecules
(mass of the element / mass of the compound) * 100
rounding rules
0.1 away from whole number → round
0.11 away from whole number → don’t round
empirical formula
simplest ratio for a formula
to find: convert to moles, divide both elements by smallest weight, find ratio
molecular formula
molar mass / empirical mass = # of each atom in the compound
limiting reactants
do stoich with both reactants, the one with the least left over is the limiting reactant
theoretical yield
what we expected to be formed from a chemical reaction
percent yield
(actual / theoretical yield) * 100
kinetic molecular theory
constant random motion
no attraction or repulsion
elastic collisions (no KE is lost)
volume of gas molecules is negligible to total gas volume
temperature is proportional to average KE of molecules
standard temp and pressure (STP)
1 atm
273.15 K
gas laws
inc P = inc T (constant - p/t)
inc V = inc n (constant - v/n)
inc V = inc T (constant - v/t)
dec P = inc V (constant - pv)
kinetic energy
1/2 mv^2
ideal gas law
pv = nrt
where r is the gas constant
real gasses
low t, high p, low v
what conditions are not ideal for gasses
strong IMFs
energy loss
small volume
Graham’s law
rate of effusion or diffusion of a gas is the sqr(mm)
diffusion
movement of gas molecules from high concentration → low
effusion
gas molecules escape collision though a tiny hole into a vaccum
vapor pressure
pressure on liquid that is exerted from evaporated vapors
high BP is caused by
low vapor pressure bc of strong IMFs
phase change: gas → solid
deposition
phase change: solid → gas
sublimation
closed system
physical boundaries, energy flows but not matter
isolated system
physical boundaries, matter and energy can not flow
open system
matter and energy can flow
solution
homogenous mixture
basically all combos of s, l, g except for solid in liquid
suspension
heterogenous mixture (particles settle/separate)
colloid
heterogenous mixture (particles disperce, fog, milk, jello)
Note
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