AP Chemistry Unit 0

Equivalent of 1cm³

1 ml

Dalton's Postulates

1. All Matter is comprised of atoms 2. Atoms of each elements are unique but all atoms of the same element are identical in chemical and physical properties 3. Law of Conservation of Mass → Matter can't be created nor destroyed 4. Law of Constant Composition → Compounds are made of a constant composition of atoms

Order in which electrons fill sublevels

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p.... D sublevel electrons = n-1 F sublevel electrons = n-2

0°C = ____ K

273.15 K

Plum-pudding model

A dense sphere studded with smaller electrons, atom is positively charged

Significant Figures

Adding + Subtracting: Round answer to same number of decimal places as the number with the fewest number of decimal places in the original problem. Multiplying + Dividing: Round answer to same number of sig figs as the number with the fewest number of sig figs in the original problem.

Name of Group 1

Alkali metals

Name of Group 2

Alkaline earth metals

Dimagnetic

All electrons are paired

Nuclide

An atom of a specific isotope

Comparison of size between an anion and its neutral atom partner

Anions are larger than their neutral atom partner because they have extra electrons → more shielding → larger radius

Isoelectric

Atoms are isoelectric when they have the same number of electrons

Solid Sphere Model

Atoms are small, solid spheres that represent an individual element

Comparison of size between an a cation and its neutral atom partner

Cations are smaller than their neutral atom partner because they have less electrons → less shielding → smaller radius

Magnetism

Caused by unpaired electrons.

Crucible

Ceramic dish Withstands higher temperatures than evaporation dish For extremely high energy reactions or ones that need a lot heat

Evaporating dish

Ceramic vessels to heat chemicals with low heat

Name of Group 6

Chalcogens

Erlenmeyer flask

Contain liquids Not used to make measurements Used with acids and bases b/c does not easily spill

Chadwick

Discovered the neutron Nucleus is held together through the nuclear strong force

Spectrum

Display of wavelengths (colors) of electromagnetic radiation

Pauli Exclusion Principle

Each orbital can only hold 2 electrons and they must spin in opposite directions

Electron Configurations and Orbital diagrams

Electron Configurations are written representations of each electron within an atom. They show the energy level as well as sublevels Orbital diagrams also show specific orbitals

Hund's Rule/Empty Seat Rule

Electrons are added one-per orbital first before a second electron is added once each orbital within a sublevel already has one electron.

Bohr Model

Electrons have different amounts of energy Bohr saw this through light emissions called bright line spectra Atoms contain different energy levels: electrons closer to the nucleus have lower energy, electrons further from the nucleus have higher energy.

Quantum Model

Electrons orbit the nucleus in distinct regions where electrons are more likely to be found called orbitals. Nucleus surrounded by electron cloud

Core electrons

Electrons that exist at every energy level below the highest

Valence Electrons

Electrons that exist at the highest energy level in an atom. Only s and p electrons

Aufbau Principle

Electrons will be added to the lowest energy state before added to the higher energy states

E = hc/λ

Energy = (Planck's constant ∙ Speed of Light)/Wavelength h = Planck's constant = 6.63 x 10³⁴ J∙s (Joules)

E = hv

Energy = Planck's constant ∙ frequency h = Planck's constant = 6.63 x 10³⁴ J∙s (Joules)

Movement between energy levels

Energy is emitted or absorbed when moving between energy levels. Energy is lost as a photon (light)

J.J. Thomson

Experimented with cathode rays and found that the particles had a negative charge by passing the rays through a magnetic field. Found mass/charge ratio Discovered the electron Updated model and called it the Plum-pudding model

Filtration

Exploits differences between solubility Solid remains trapped in filter, liquid is collected in a vessel

Distillation

Exploits differences in boiling points Boiled substance leaves as gas and is collected, higher boiling point substance remains

Evaporation

Exploits differences in boiling points, but only substance with higher boiling point is collected

Decantation

Exploits differences in densities and solubility Ex: Oil & Water → Oil is less dense and floats on top

Chromatography

Exploits differences in polarity

Coulomb's Law

F = (k∙q₁∙q₂)/r² F = Force of Attraction q₁ and q₂ = charge of the 2 particles r = distance k = constant: when particles in air = 9 x 10⁹ N

Compounds

Formed when two or more atoms of different elements bond chemically

Rutherford

Gold foil experiment Alpha particles were shot at gold foil, most went straight through, a few were dramatically deflected Discovered the nucleus and updated model to the planetary model

Columns on the Periodic Table

Groups

Name of Group 7

Halogens

Test Tube

Hold and heat liquids Contain small amounts of chemical reaction

Accuracy

How close you are to the true value

Diatomic Elements

Hydrogen Oxygen Nitrogen Chlorine Bromine Iodine Fluorine HONCLBRIF

Atomic Radius Trend on Periodic Table

Increasing the Z eff decreases the radius of the atom. Radius decreases left to right in periods Radius increases up to down in groups because of more energy levels

Ionization Energy Trend on Periodic Table

Ionization energy increases left to right in periods because Z eff increases. Ionization energy increases down to up in groups because size decreases

Polyatomic ions

Ions that comprise of multiple atoms which have a charge

Homogeneous Mixtures

Mixtures that are uniform throughout Ex: Solutions

Heterogeneous Mixtures

Mixtures where the component parts are not spread uniformly throughout the mixture Ex: Marble

Planetary Model

Mostly made up of empty space with a small, dense, positively charged nucleus orbited by electrons

Anions

Negatively charged ions

Beta Particles

Negatively charged, essentially electrons

Gamma Rays

No mass or charge, essentially pure energy

Name of Game 8

Noble Gases

Millikan

Oil Drop Experiment Found mass of electron → led to finding the charge of an electron using mass/charge ratio

Electron Configuration of Ions

Only the outermost electrons are added or removed. Ex: Iron →[Ar] 4s²3d⁶ Iron (+3) ion →[Ar] 3d⁵

PES graph

Peak outputs represent the # of electrons ejected at a specific energy Relative height of each peak represents the different sublevels Position of peaks represent amount of energy needed High energy usually on left

Rows on the Period Table

Periods

Islands of Stability

Places on the period table where sublevels are completely filled or half filled. These are places where ionization energy is higher than expected and where there is a lesser magnitude of electron affinity -Alkaline earth metals -Manganese group -Zinc group -Nitrogen group -Noble Gases

Absolute Zero

Point where molecules stop moving, 0 K

Cations

Positively charged ions

Alpha Particles

Positively charged, essentially a helium nucleus

Extensive Properties

Properties that are dependent on how much of something you have Ex: Mass, Volume

Intensive Properties

Properties that are independent on the amount of substance present Ex: Density, boiling point, color, odor, temperature

Physical Properties

Properties that can be observed without changing the identity/composition of the substance Ex: Color, Odor, Boiling Point, Hardness, Density

Chemical Properties

Properties that can only be examined when changing a substance Ex: Flammability, Reactivity

Noble gas configuration

Puts most previous noble gas in brackets and then the electron configuration for the electrons in the next period

Red Martians Invented Very Useful X-Ray Goggles

Radio Microwave Infrared Visible Ultraviolet X-Ray Gamma ray In order from longest to shortest wavelength

ROY G BIV

Red Orange Yellow Green Blue Indigo Violet In order from longest to shortest wavelength

Unit system used in chemistry

SI system

Isotopes

Same number of protons, different number of neutrons

Electromagnetic spectrum

Shows all varying wavelengths

c = λ ∙ v

Speed of light = wavelength ∙ frequency Speed of light = 3 x 10⁸ m/s Higher frequency = shorter wavelength

Pure Substances

Substances that have only one species (type of element) present

Electronegativity

The attraction by the nucleus of an atom on electrons

Ionization energy

The energy necessary to remove an electron from a gaseous state atom.

Wavelength

The length in between the peaks or troughs of a wave Measure in m or nm Represented with the Greek letter λ (lambda)

Average atomic mass

The mass shown on the period table. Calculated via weighted average by taking into account of the relative abundance of each isotope.

Frequency

The number of cycles per unit time Measured with unit Hz (Hertz) Represented with Greek letter v (nu)

Precision

The proximity of each trial to the other trials

Energy Levels

The quantum positions of distance away from the nucleus. Represented as numbers 1-7 with the variable 'n' The higher n is, the further away those electrons are, and the more energy they have.

Chemistry

The study of composition, properties, and reactions of matter

Paramagnetic

There are unpaired electrons

Photoelectron Spectroscopy (PES)

There is a sensor that can tell when an electron is ejected from an atom. Gives output of the # of electrons ejected in a graph Electrons are ejected when they get energy greater than their binding energy

Excited State

There is at least one electron that is in a higher energy level than it should be.

Beaker

To contain and mix liquids Not used to make measurements Transport only

Graduated cylinder

To make precise measurements Liquids only, measure from bottom of meniscus

Volumetric flask

To measure extremely precise amts of solution Can only measure one certain volume Many diff sizes

Pipette

To measure or transfer a very small amt of liquid

Mass spectrometer

Tool used to measure the atomic weight of a sample A gaseous form of an element is negatively charged and sent through a magnetic field and a sensor shows average mass of each isotope. Heavier isotope is not deflected as much as lighter isotopes

Mole

Unit used to measure huge quantities of particles 6.022 x 10²³ particles/mol

Buret

Used for accurate measurements of liquid volumes

Shielding

When Electrons repel each other: Core electrons repel outer electrons Pushes outer electrons further away

Mixture

When elements or compounds are combined physically

Sublevels

Within energy levels Comprised of orbitals, each orbital can have a max of 2 electrons s → 1 orbital → 2 electrons → spherical shaped p → 3 orbitals → 6 electrons → dumbbell shaped d → 5 orbitals → 10 electrons → dumbbell w/life preserver shaped f → 7 orbitals → 14 electrons → wonky shape

Effective Nuclear Charge

Z eff Calculated by subtracting # of core electrons from # of protons in nucleus Force of Attraction increases as Z eff increases Force of attraction to valence electrons decreases as # of energy levels increases

Periodic Table Trends of Z eff

Z eff increases down the period Decreases down groups