chemistry honors final (fulllllll year)

what 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

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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

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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

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trend: ↙

coulombs law

opposite charges attract

what are the two main factors that cause atoms to have a strong attractive force?

1. smaller radius

2. 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)

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BOOOOOOOOOOOOM

scientific notation

\#>1: move decimal left for a POSITIVE 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)