AP Chem

Accuracy How close measurement is to accepted value

Precision When a group of measurements is close together

Sigfig Rules 1. For all nonzero digits any appearance is 1 sigfig 2. 0s in the middle of a number(e.g.1001) are sigfigs 3. 0s at the front are not sigfigs(e.g. 000.021 has 2 sigfigs) 4. Trailing 0s are sigfigs if a decimal is present, but not otherwise

Numbers that have no/infinite sigfigs Definition numbers(Defined ratios e.g. 1000g = 1kg) Counted values

Sigfig multiplication Round result to least amount of sigfigs in numbers used

Sigfig addition & subtraction Find lowest place value occupied by sigfig in each number. Find largest, round to that place value

Multistep sigfig arithmetic First do math, then round at the end

Temperature Measure of average kinetic energy

Intensive  Property of matter that does not change with amount

Extensive  Property of matter that changes with amount

Mass How much stuff

Weight Downward force applied by an object from gravity

Classifications of Matter Pure and Mixtures

Types of Pure Substances Elements and Compounds

Element Any substance composed entirely of one type of atom

Compound Chemically combined group of two or more atoms in a fixed ratio

Types of Mixtures Homogeneous, Heterogeneous

Homogeneous Mixture Components mixed at molecular level

Heterogeneous Mixture Not mixed at molecular level

Physical Property Does not revolve around changing identity of substance

Chemical Property  Precursor sentence of how a reaction would/would not happen

Physical Change Does not change substance identity

Centrifugation Spin fast to separate by density

Filtration Filters based on permeability of membrane(e.g. paper)

Chromatography Mobile Phase, Stationary Phase, mobile phase travels along stationary phase, separating components of mixture

Distillation Separation by boiling point, liquid is boiled and vapor rises up, eventually liquid goes through tube to container

Conservation of Matter Matter cannot be created or destroyed(not generally true, but true in chem)

Law of definite proportion A given compound has a given formula unchanching anywhere in the universe

Law of Multiple Proportion Two can come together in different ways

Avogadro's law The volume of a gas is proportional to the number of particles, not particle size

Four fundamental forces 2 nuclear forces(strong, weak), Gravity, Electromagnetism(positive, negative charge)

Symbols for proton, neutron, and electron p+, n^0, e-

Location of proton, neutron, electron Proton & neutron: in nucleus, electron not in nucleus

Charge of proton, neutron, electron P: 1+, N:0, E:1-

Mass of proton, neutron, electron P: 1 amu, N: 1amu, E: ~ 0.001 amu

Atomic Symbol Format First letter capitlized, next ones never caps

What does the atomic number tell you Amount of protons

What determines identity Only the amount of protons

Neutral atom proton and electron amount "#P = #E"

What can atoms lose or gain Electrons, not protons

Cation Positive charge, from neutral atoms losing electrons

Anion Negative charge, from electrons added to neutral atom

Atomic Mass "# of protons + neutrons"

Atomic mass on periodic table Weighted average of all isotopes

Perioidic table groupings Vertical groups = groups, Horizontal = periods

Periodic table stairstep line Divides metals and non metals

Properites of metals Tend to have high melting point & boiling points (exception of mercury) STP: 0 C, 1 atmosphere High Luster Malleable Ductile Good elec & heat conductor Tend to form cations

STP Standard temperature & pressure

Luster High is shiny, low is dull

Malleable Can be pounded into a sheet

Ductile Pulling out forms wire

Properties of nonmetals Tend to have low melting & boiling point Tend to be dull Poor heat & elec conductor Tend to be brittle Tend to form anions 7 nonmetals are diatomic, but they can be found when they are ions since they are not atoms

Diatomic Not found in nature in elemental form

Diatomic Nonmetals H O F Br I N Cl

P Table Group 1 (Not including hydrogen) Alkali metals, very reactive, always make +1 ions in compounds

P Table Group 2 Alkaline earth metals, make 2+ cations, not as reactive as alkali

P Table Groups 3-12 Transition metals

P Table Group 17 Hallogens, very reactive, form 1- ions

P Table Group 18 Inert/Noble Gases, not very reactive, do not bond

P Table bottom elements Inner Transition Metals

Ions formed by groups 13, 14, 15 , 16 , 17 13: 3+, 14 don't tend to beond in ionic compounds, 15: 3-, 16: 2-, 17: 1-

How does ionic bonding occur Cations & anions attract to each other until no longer attracted, their charges cancelling to form a charge of 0 (e.g. Na+ + Cl- = NaCl

Ionic Compound Naming Cation first, then anion Cation always keeps name, anion of monotomic changes name to end in -ide NaCl != Sodium Chlorine, NaCl = Sodium Chloride

Polyatomic Ion Group of atoms with a charge shared between them(e.g. SO42-,PO43-)

Polyatomic Ions to Remember Nitrate, Sulfate, Phosphate, Oxalate, Ammonium, Chlorate, Perchlorate, Sulfite, Phosphite, Hydroxide

Nitrate NO3-

Sulfate SO42-

Phosphate PO43-

Oxalate C2O42-

Ammonium NH4+

Chlorate ClO3-

Perchlorate ClO4-

Sulfite SO32-

Phosphite PO33-

Hydroxide OH-

Sulfur Derivate and Oxalate Charge 2-

Phosphorus derivative chage 3-

Ammonium Charge 1+(or just +)

Acid Nomenclature "Hydro__ic acid: binary covalent molecules with a hydrogen ion(e.g. HCl Hydrochloric acid) _____ic acid: binary covalent molecules with a hydrogen ion bonded to a polyatomic ion that ends in -ate(e.g. H2SO4 Sulfuric AcidS) ______ous acid: binary covalent molecules with a hydrogen ion bonded to a polyatomic ion that ends in ite(e.g. H2SO3 Sulfurous Acid) "

EM Def and Properties Electromagnetic Radiation, type of energy, includes light, is a wave, requires no medium, electric & magnetic wave running perpendicular

Top & Bottom of Wave Crest, Trough

Wavelength Distance between two identical points on subsequent waveforms

Amplitude Distance between wave crest and mid line

How do waves move They propagate, they do not travel

Frequency How many waves pass in a second(Variable V), unit of Hz(Hertz)

Quantized Light & energy from light is quantized(only int values) E.g. Steps are quantized(When you step 0.5 steps up you fall back down)

Photoelectric Effect If photon has enough energy, when it hits metal an e- bounces off. As frequency increases, the kinetic energy of the e- increases

Special Properties of Light Light is energy but has mass when moving, so it has no resting mass. When a photon stops moving it stops existing.

Double Slit Experiment Waves sent through double slit, propagated out of slits as if they originated from them. Creates pattern on background screen.

Constructive Interference Waves meet each other and align, matching crests and troughs, combining

Destructive Interference Two waves overlap and cancel each other out

Electron Special Properties Since it is very small it is both a wave and a particle

Continuous Spectrum Measuring of EM wave all frequencies appear in approximately the same ratio

Line Spectrum Only specific wavelengths appear, comes from electron excitation

Bohr Model Nucleus in middle, electrons in spheres, each takes more energy to get into and more electrons, only correct until 2-8-8 electron configuration

Change in Energy Final - Initial

 Energy for different electron groups Each energy gap gets closer the more energy levels(electron rings)

Model of Real Electron Moving Through 1 Dimensional Universe Since it is a standing wave, it exists everywhere but at varying probablities, with one node at the start, end, and middle where the amplitude is 0. The higher the amplitude at one point, the more likely to be intercepted at that point

Graphs of one ray of an orbital "Attraction to nucleus decreases with distance, # of positions increases with distance. Attraction to nucleus starts decreasing at a faster rate so the probability of an electron being somewhere on that ray decreases at a certain point."

What is encompassed by an orbital Since the orbital goes on forever, it is defined to encompass 90% of the volume occupied by the density of the electron

S Orbital Set of rays from nucleus creates spherical orbitals, 1 per energy level

P Orbital 3 Orbitals per level except first level. py, px, and pz orbital, together making a p sublevel

d orbitals 5 orbitals. 4 of them look like 4 leaf clovers, 1 look slike a p orbital with a donut wrapped around it. Excludes first 2 energy levels

f orbital 7 orbitals, except for first 3 energy levels

Standing Wave At some points called nodes there is 0 amplitude and it appears to stay still

Degenerate Two or more waves are degenerate if they have the same energy

How many electrons can a given orbital hold 2 maximum

Pauli's Exclusion Principle If an orbital has 2 electrons they must have different spin

Spin Up(+1/2) or down(-1/2), property of electrons in an atom, not twirling(involves magnets), spin is fluid and can be changed

Aufbau Principle Electrons fill into an atom from lowest to highest energy sublevel

Periodic Table Orbital Blocks S block: Groups 1 & 2 + He P Block: Groups 13-18 D Block: Groups 3-12(Excluding inner transition metals, starts at 3d) F Block: Inner transition metals(Starts at 4f)

Hund's Rule When a sublevel is only partially filled, we must do so in a way that maximizes spin(electrons have the same spin in different orbitals so spin adds up to more)

Electron Configuration Shorthands Sublevel and then electron amount(e.g. 1s22s2...) Checkpoint and then electron amount e.g.[Rn]7s2  Checkpoint comes right after the noble gas

4 Types of Quantum Numbers Principal, Angular Momentum, Magnetic, Spin

Principal QN n Bounded [1, inf) Tells energy level of electron

Angular Momentum QN l Bounded based on n: [0, n-1] Tells sublevel(0=s, 1=p, 2=d, 3=f)

Magnetic QN ml  bounds: [-l, l] Tells orbital number(Which orbital in the sublevel) e.g. For 6d the orbitals are -2, -1, 0, 1, 2 For 1s the orbitals are 0

Spin QN ms  +1/2 or -1/2 Tells spin of electron

Mendeleev's Periodic Table Organized by atomic mass He predicted a missing element and was right about its properties

What is the modern periodic table organized by Number of protons(atomic number)

Atomic Radius and how it is found  Distance between nucleus ot outermost edge of electron shell. For atoms that can covalently bond, it is half the distance between the nuclei of 2 single bonded atoms of the same type

Atomic Radius in relation to moving through the periodic table Going down a group, atomic radius increases as the energy levels are larger Left to right, radius goes down as more protons are in the nucleus attracting electrons. This is a trend, not a rule and there are exceptions

Ionic Radius Properties Cation always smaller than atom from which it arises. Anion always larger than atom from which it arises. With isoelectric ions, the greater number of protons the smaller it is

Ionization energy Amount of energy to remove an electron from an atom. Generally: Larger atom, smaller ionization energy

Preferred States Full sublevel preferred, half full is semi preferred

First Ionization Energy Neutral to +1

Pattern for energy of ionization Each succesive ionization is always more energy than the one before it, nonlinear relationship

Electron Affinity Energy change when an electron goes into a neutral atom

Which groups have high positive and negative electron affinity Noble gases have high positive, hallogens have high negative Group 15 has a more positive affinity than 14 or 16 as it is in a semi preferred state

Pattern of electron afffinity in going up the perioidic table Going up usually means more negative Exception of period 2 as the sublevel is small enough that the electrons push each other off

Electronegativity An atom's ability to attract another atom's electrons in a bond Atoms that cannot bind have no electronegativity(e.g. He, Ne)

How is electronegativity measured Relative to fluorine which is the most electronegative with a value of 4.

Coulomb's Law "Electrostatic attraction is proportional to the product of the magnitudes of two charges and inversely proportional to the square of the distance (the combined atomic radii) between them."

Avogadro's Number 6.02 * 1023

Atomic Mass Unit Definition 1/12 the mass of a Carbon-12 atom

Molecular vs Empirical Formula Molecular shows exact amount of each atom in one molecule, Empirical shows ratios