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Samarth Shah-Period: 3 (Equilibrium (-Chemical equilibrium is achieved…
Samarth Shah-Period: 3
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Atomic Structure
Models
-J.J Thompson(Plum pludding): the plum pudding model which showed the embedded “raisins”, which indeed were electrons each with a negative charge
-E. Rutherford(atomic nucleus): model shows alpha particles being shot at the center of an atom and being deflected because of the nucleus being positive like alpha particles
-N. Bohr(planetary model): shows nucleus with orbits containing electrons
-J. Dalton: shows nucleus with protons and neutrons and shows the electrons with the orbits
-Democritus: showed that all matter is made up of atoms and chemical reactions rearrange atoms
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Discoveries
-Electron: J.J. Thompson discovered the electron using the cathode ray tube experiment when he found that many different metals release cathode rays made of electrons, very small negatively charged particles.
-Nucleus: Rutherford discovered by the Gold Foil Experiment which happened when shooting alpha particles at the center of an atom and watching them deflect because of the nucleus(positively charged) in the center of an atom.
Atomic #(Z)
-Equal to number of electrons
-Equal to number of protons
Mass Number(A)
-A=Z(atomic#/protons/electrons)+N(neutrons)
Atomic Mass
-Atomic Mass=(Isotope mass)x+(Isotope mass)(1-x)
-x=percent abundance
Isotope
-Element with same number of protons and electrons, but different number of neutrons changing the mass number
Nuclear
Half-Life: The term half-life is the time it takes for 50% of the atoms of a radioactive material to go under radioactive decay.
-Equations:(t/T=number of half-lives)
-mt=m0*(0.5)^t/T
-t/T=[log(mt/m0)]/[log(1/2)]
The differences between chemical and nuclear reactions:
-Nuclear reactions change the nucleus while chemical reactions change the arrangement of atoms
-Chemical reactions are small changes while nuclear reactions are on a larger scale
-Chemical reactions happen when bonds are broken while nuclear reactions happen when nuclei emit rays and particles
Radioactive Particles:
-Alpha: 4He2
-Beta: 0e-1
-Gamma: 0y0
-Positron: 0e1
-Proton: 1p1
-Neutron: 1n0
*decays conserve all the numbers
Nuclear Fission: The splitting of a heavy, unstable nucleus into two lighter nuclei.
Nuclear Fusion: Where two light nuclei fuse together releasing energy.
Empirical Formula
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If you want to go from empirical to molecular:
(molar mass of molecular formula)/(molar mass of empirical formula)
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Thermo Chemistry
q=mc△T
- q=change in energy
- m=mass
- c=specific heat
- △T=change in temperature(Tf-Ti)
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Phase Changes
-The temperature must not change during a phase change
-q=mc△T for temp. change and no phase change
-q=mHf for no temp. change and phase changes
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Gas
Theory
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1) Elastic collisions occur between gas particles
2) No forces of attraction or repulsion between gas particles
3) Avg. kinetic energy produced depends on temperature
4) Gas particles move in random ways to produce kinetic energy
Gases are compressible, effuse, diffuse, and have low density
-As pressure increases, volume decreases and vise versa
-Pressure increase because there is an increased amount of gas particles hitting the walls
Important values
1 atm=760 mmHG, 760 torr, 101.3kpa
Dalton's Law of Partial Pressures
-PT=P1+P2+P3...
-Total pressure is equivalent to the sum of the partial pressures of each gas
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Solutions
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Saturated solution: Maximum is dissolved in a reaction
Unsaturated solution: Less than maximum is dissolved in a reaction
Kinetics
Collisions
-Must have enough energy to perform the reaction
-As collision freqeuncy increases, the overall reaction rate will increase as well
Reaction Rate
-△[A]/△t
-Measures the amount of time until all the reactants are consumed in the chemical reaction
-Differential rate laws show the relationship between rate laws and concentration of the reactants in a given chemical reaction
-Increasing temperature speeds the reaction
-Increasing surface area speeds the reaction
-Increasing concentration speeds the reaction
Rate Expressions
Ex. 2NO + Cl2 ==> 2NOCl
- -△[NO]/2△t=-△[Cl2]/△t = △[NOCl]/2△t
Equilibrium
-Chemical equilibrium is achieved when the rates of the forward and backward reactions are equivalent to one another
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Equilibrium Expression
-wA+xB <==> yC+zD
-K=[C]^y[D]^z/[A]^w[B]^x
-for pressure, remove brackets and put capital P and reactants and products as subscript
-Q and K calculated the same way like this
If Q=K, the equilibrium is achieved.
If Q>K, there is a shift to the left direction.
If Q<K, there is a shift to the right direction.
Le Chatelier's Principle: When there is a stress placed, the reaction will respond in a specific way to relieve that stress.
Acids/Bases
Acids
Properties
-Tart, sour, bitter taste
-Electrolytes that conduct electricity
-Aqueous and liquids
Definitions
Arrhenius Model
-Produce hydrogen ions in aqueous solutions
Bronsted-Lowry Model
-Proton donors
Lewis Acid Model
-Electron pair acceptors
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Bases
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Definitions
Arrhenius Model
-Produce hydroxide ions in aqueous solutions
Bronsted-Lowry Model
-Proton acceptors
Lewis Acid Model
-Electron pair donors
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Salts
-To find whether the salt is acidic, basic, or neutral, align with HOH and cross and use chart
-Write the chemical equation depending on what the result from doing the thing above turns out