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Chemistry A Period Stephanie Shao Abigail Richardson (Nuclear…
Chemistry
A Period
Stephanie Shao
Abigail Richardson
Thermochemistry
Enthalpy
Change in heat energy
Calorimetry
Specific Heat Capacity
Energy needed to raise the temperature of one gram of substance one degree Celsius
Hess's Law
Standard Enthalpies of Formation
Exothermic and Endothermic
The Delta H value for exothermic reactions is negative
The Delta H value for endothermic reactions is positive
The transfer of energy as heat
Temperature is the measure of the average kinetic energy of a sample
Thermodynamics
Three Laws of Thermodynamics
Energy can neither be created nor destroyed; energy can only be transferred or changed from one form to another
The entropy of any isolated system always increases
The entropy of a system approaches a constant value as the temperature approaches absolute zero
Entropy
Entropy is the measure of molecular randomness, or disorder
Increases in entropy
Greater number of moles
Solid to liquid, or liquid to gas
Larger volume
Spontaneity (Delta G)
When Delta G is negative, the reaction is spontaneous
When Delta G is zero, the reaction is at equilibrium
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When Delta G is positive, the reaction is not spontaneous
Gibbs Free Energy (Delta G)
The energy associated with a chemical reaction that can be used to do work
Delta G= Delta H-(T times Delta S)
H is enthalpy
S is entropy
T is temperature
Kinetics
Things That Can Affect Reaction Rate
Nature of Substances
Certain substances reacting are just faster, like acid-base reactions
Surface Area
Breaking things into smaller substances increases surface area and increases the reaction rate
Concentration
More molecules=more likely to collide+react
Temperature
Higher temperatures=molecules moving more quickly=more likely to collide+react
Catalysts
Provide an alternate path for the reaction to occur that requires less activation energy
Pressure/Volume
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Increased pressure=more collisions+reactions
Reaction Graphs
Equilibrium
ICE Tables
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LeChateliers' Principle
Every system in a stable chemical equilibrium submitted to the influence of an exterior force will undergo modifications which counter that force
If a reaction at equilibrium gets crowded or stressed on one side , the equilibrium will shift to the other side
Higher pressure favors fewer moles
If aA+bB-->cC+dD
Keq= (C^c)(D^d)/(A^a)(B^b)
Liquids and solids are not included on the right hand side
Atomic Theory
Dalton's Theory
Good
All matter is composed of atoms
Atoms combine to form simple whole number chemical components
In chemical reactions, atoms are combined, separated, or rearranged
Wrong
Atoms of a given element are identical in mass and size
Incorrect because of isotopes
Atoms cannot be subdivided, created, or destroyed
Incorrect because of nuclear fission
Atoms
Electrons
Neutrons
Protons
Solutions
Raoult's Law
Vapor Pressure
Like dissolves like
Polar solvent and polar solute
Non-polar solvent and non-polar solute
Factors that change the rate of a solute dissolving
The more surface area of the solute, the faster it dissolves
Agitating a solution
Heating the solvent
Saturation
Under-saturated
Saturated
Super-saturated
How much solute can be dissolved in a solvent compared to how much solute is in a solution
Periodicity
The tendency of elements to have similar properties when arranged according to atomic number
Atomic Radius
The size of an atom from the nucleus to the outermost shell
Smaller across a period, larger down a group
Ionization Energy
The energy needed to remove an electron from a neutral atom
Larger across a period, smaller down a group
Electronegativity
The measure of the ability of an atom to attract electrons
Larger across a period, smaller down a group
Electron Afinity
The energy change that occurs when an electron is acquired by a neutral atom
Larger across a period, smaller down a group
Acids and Bases
Henderseon-Hasselbach Equation
ICE Tables
Titration Graphs
Acids donate protons
Bases receive protons
pH is a logarithmic measurement of acidity
Related to H3O+ concentration
Electrochemistry
Redox
OIL RIG
Reduction Gains electrons
Oxidation Loses electrons
AN OX RED CAT
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Anode=oxidation
Reduction=cathode
Types of Cells
Galvanic Cells
Voltaic Cells
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Nuclear Chemistry
Alpha Particles /Decay
Emits an alpha particle (helium nucleus)
Beta Particles/Decay
Emits an electron
Gamma Rays/Decay
Emits dangerous EMR waves
Positron Emmission
Emits a positron (a positron and a neutron make a proton)
Neutron Emission
Emits a neutron
Electron capture
The nucleus captures a low energy electron and combines it with a proton to form a neutron
Nuclear Reaction
Reaction that affects the nucleus of an atom
A radioactive element will continue to change and lose particles until it becomes stable
Nuclear Fission/Fusion
Nuclear Fission is when a heavy nucleus splits into more stable nuclei of intermediate mass
Nuclear Fusion is when nuclei with a small mass is combined to form a heavier, more stable nucleus
Half-Life
The half-life of any given element is how much time is required for one half of its sample to decay
Molecular Geometry
Steric Number=4
Tetrahedral (4 bonding electron pairs)
Trigonal pyramidal (3 bonding electron pairs, 1 lone pair)
Angular (2 bonding electron pairs, 2 lone pairs)
Steric Number=3
Trigonal planar (3 bonding electron pairs)
Bent (2 bonding electron pairs, 1 lone pair)
Steric Number=5
Trigonal bipyramidal (5 bonding electron pairs)
Seesaw (4 bonding electron pairs, 1 lone pair)
T-shaped (3 bonding electron pairs, 2 lone pairs)
Linear (2 bonding electron pairs, 3 lone pairs)
Steric Number=2
Linear (2 bonding electron pairs)
Steric Number=6
Octahedral (6 bonding electron pairs)
Square pyramidal (5 bonding electron pairs, 1 lone pair)
Square planar (4 bonding electron pairs, 2 lone pairs)
Steric Number=7
Pentagonal bipyramidal (7 electron bonding pairs)
The steric number is the number of lone pairs plus the number of atoms bonded to the central atom
VSEPR Model
Valence Shell Electron Pair Repulsion
Focuses on the bonding and nonbonding (lone) electron pairs present in the valence shell of the central atom
Gas Laws
Boyle's Law
If temperature is constant: when pressure increases, the volume decreases
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Charles's Law
If pressure is constant: when temperature increases, volume increases
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Ideal Gas Law
PV=nRT
Kinetic-molecular theory
Gases consist of small particles far apart
Collisions are elastic
Gas particles are in continuous motion
No attraction or repulsion between particles
Kinetic energy is directly related to temperature
Gases that act ideal tend to be...
at a high temperature
at a low pressure
smaller, and non-polar
Avocado's Law (Avogadro's Law)
If temperature and pressure are constant: when volume increases, number of moles increases
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Gay-Lussac's Law
If volume is constant: when temperature increases, pressure increases
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Periodic Table
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Periodic Table Coggle Link
Intermolecular and Intramolecular Forces
Intermolecular Forces
The forces between compounds
Dipole-dipole forces
Hydrogen bond
Strong dipole-dipole
Hydrogen with nitrogen, oxygen, or fluorine
Positive end of a molecule is attracted to the negative end of another molecule
London Dispersion Forces
Temporary attractive force that results when the the atoms form temporary dipoles
Intramolecular Forces
Keeps individual atoms together
Ionic
Between nonmetals and metals
Crystal lattices
Electrons are taken and then ionic charge keeps atoms together
Covalent
Between nonmetals
Electrons are shared
Metallic
Between metals
Free-floating valence electrons are shared by all in a sea of electrons
Bees are dying at an alarming rate
