I. Scientific methodChemisty Chapter 1 NotesI. Scientific method- Steps of The Method1. Observation2. Formulation of Hypothesis3. Prediction4. Testing- Law vs. Theoryo Law: Summarizes many observationso Theory: Provides an explaination for laws, cannot be proven- Molecular Perspectiveo Chemists are interested in the dtructure ofmatter at the particulate levelo Matter is the physical materials found in ourenvironment, consists of atoms and moleculesII. Birth of Modern Chemistry- Lavoisier Debunks Phlogistron Theoryo Phlogiston Theory: Originally it was believed materials that burn contain phlogiston and burning it left a residueo Lavoisier realized this was false when he discovered the Law of Conservation Masso Lavoisier is considered: Father of Modern Chemistry Founder of Law of Conservation First to classify elements and compounds- Element vs. Compoundo Element: Pure substance, unbreakableo Compound: Pure substance that can be broken into small subunits- Law of Conservation of Masso Mass is never created or destroyed- Law of Definite Proportionso Elements in a compound are always in a constant porportion- Law of Multiple Proportionso When two elements can combine and make multiple compounds, the ratios are represented by two whole numbersIII. Atomic Theory- John Dalton (1804)o Discovered that elements are composed of atoms Found that they are unchangeable and never dissappearo Molecules refer to either elements of compounds Atoms can combine to form compounds- Mass is very important; it’s the cornerstone of modern chemistryIV. Atoms & Molecules- Joespeh Gay-Lussac (1808)o Discovered the Law of Combining Values: Volumes of reaction gases are in simple, whole number ratios- Law of Combining Volumeso H2O experiment: He found that 2H + 1O = H2O- Amadeo Avagadro (1811)o Avagadro’s Law: Equal columes of gas (at controlled pressure and temp, contain an equal number of molecules Figured out that even though oxygen is an element, it is mostly availible as O2 because it is diatomic- The Diatomic Elementso Atoms that are primarily availible diatomically H2 N2 O2 F2 Cl2 Br2 I2- Class Discussiono Atoms consist of protons, neutrons,and electrons Electrons orbit around the nucleus If the number of protons is equal to the number of electrons, the element is a normal atom If it loses or gains electrons it is an iono Atoms are measured 1A = 1*10-10 m Roughly 1-5 Angstromso Atomic Composition: Each unit has different weightsV. Mole & Molar Mass- Masso Masses on periodic table are based aroundcarbon Each one was assigned it’s numberbased on C Isotopes have varying mass numbers,but always have the same atomic number- Moleso Number of atoms or molecules present in a sample when the mass is equalto it’s molecular masso Mole: Number of atoms is the relative mass of it’s molecules- Calculating Nucleonso Subrtact atomic number from the mass number to find nuetron number- Molar Masso AMU: Atomic mass unitso Avagadro’s Number (NA):6.022*1023- Mass to Mole Coversionso Conversion Factors: Theappropriate factor that you need tomultiply the given quantity by- Stoichiomentric Factoro Also known as the conversion factoro Limiting Reactant: the reactant of which we have the leastVI. Energy- Kinetic Energyo The energy of a substance is the the sum of its kinetic energy and its potential energyo Kinetic Energy: Energy of motion- More On Energy o Potential Energy: Energy due to position Potential energy in dynamite is a result of the relative positions of the atoms in the moleculeso Energy equation: KE = 1/2mv2o ΔE = final energy – initial energy = Ef - Ei- Systems in Nature seek position of lowest energyVII. Electromaagnetism & Coloumb’s Law- Electromagnetic Force:o Force of interaction between cahrged particled when they’re brought closeto one another- Coloumb’s Law:o Two particles of charge q1 and q2 separated by distance r experiencea force Fo Coulomb’s Constant: k = 8.9875*109 F = kq1q2/εr2 (Equation of Force)- ε is the dielectric constant- q1 and q2 are the charges inCoulomb’s- ε=1 in a vaccum, but ε=79 inwater When F is negative, the force isattractive When F is positive, the force is repulsiveo Opposite charges attract, Like forces repel- Class Discussiono As ion charge increases, the attractive force increaseso As the distance increases, attractive force decreaseso Electrostatic Forces Divalent anions with divalent cations has 4x the energy and 2 monovalent ions Charge on the ions themselves depends on physical properties- Energy Equationso Energy is defined as a force exerted through a distance E = F*ro Change in potential energy can be found by multiplying equation of force by r to get the Energy of interaction E = kq1q2/ε*rVIII.Atomic Structure- JJ Thompson (1897)o Cathode Ray Rays were deflected by electric and magnetic rays, -Found the charge to mass ratios-Cathode rays are particles He discovered there were negatively charged particles- First to discover electrons- Robert Millikan (1909)o Electron Charge Used an oil drum and found the terminal speed of oil droplets, adjusted voltage until it was suspended mid air Using the electrostatic and gravitational forces he was able to determine the charge. The charges all corresponded to -1.6*10-19- Rutherford (1911)o Gold Foil Experiment Observed 1 in 20,000 α-particles were deflected and determined the existence of the nucleus Found it to be 1/20,000 the size of the atomIX. Subatomic Particles- Atomic Numbero The number of protons in the nucleus (Z)- Mass Numbero The sum of the number of protons and the number of neutrons (A)o Molecular Weight: sum of atomic weights of all atoms in a moleculeX. Isotopes & Ions- Isotopeso Different form of the same element Same atomic number, different mass The behave differently, as shown o Isotopes in existance are averaged to give usthe mass number on the periodic table.- Chargeo It’s not continuous, it comes in bundles of 1.6*10-19 C Charge of particle = # of protons - # of electronso Atoms have no charge, if they lose or gain electrons they become ions- Ionso Cations: Produced when electrons are losto Anions: Produced when electrons are gained Metals tend to lose electrons Non metals tend to gain electrons Noble gases don’t form ions at allXI. Mendeleev & Periodic Law- Mendeleevo The Periodic Table He arrange elements in order of their atomic masses- Columns form families or