1 Chemistry Is The Study Of Matter! Matter is anything that has mass and a volume (which is also related to density). The entire known universe (15 Billion Light Years in diameter) is 99% empty space! CONTAINS NO MATTER! 2 Subatomic Particle LocationMass in Atomic Mass Units (A.M.U.) Charge ProtonNucleus1.0+1 NeutronNucleus1.0Neutral or 0 ElectronsOrbitals around nucleus 1/1347 (adds nothing to atom) The structure of an atom based on the three main subatomic particles. 3 Isotopes are atoms which are the same elements (same number of protons) but have different numbers of neutrons. The Three Isotopes of Hydrogen Look at the three isotopes of hydrogen and note the differences. Protium mass = 1 A.M.U. Deuterium mass = 2 A.M.U. Tritium mass = 3 A.M.U. 4 What is the difference between atomic mass number and average atomic mass? The atomic mass number is the number of protons + the number of neutrons in one atom of an element. Average atomic mass is the average mass of all of an atoms isotopes. This mass is shown on the periodic table. 5 Review what we have learned! Matter made of atoms Atomic mass number = # protons + # neutrons Protons & neutrons in nucleus, each has a mass of 1 AMU. Protons +1 Neutrons 0 Electrons outside nucleus in oribitals, have almost no mass. Charge -1 Average mass of all Isotopes is atomic mass on periodic table. 6 Matter has mass & volume which is density. Density = mass/volume Units for mass are grams (g) or kilograms (Kg) Units used for volume are milliliters (mL) or centimeters cubed (cm 3 or ccs) Density can impact your life! The loss of bone density! 7 Here are the densities of some common materials 8 Looking at the chart Ice floats in water Oak wood floats in water Aluminum sinks in water The density of an object determines if it floats or sinks in water Objects with a density greater than water sink. Objects with a density less than water float. 9 How do we calculate density? 1. Density = mass/volume; D=m/v 2. Information we need to collect(mass g) (volume mL or cm 3 ) 3. Remember that 1 mL = 1 cm 3 4. Three tools can be used to calculate density 5. Mass in grams (balance) 6. Volume irregularly shaped object in mL (graduated cylinder) water displacement 7. Volume regular shaped object in cm 3 (ruler) length x width x height 10 Location of the metals, metalloids/semimetals, & nonmetals on the periodic table 11 Most of the elements are solid at room temperature. The only exceptions to this are: 1. mercury and bromine are liquids are gases with 5 of them being diatomic. These are the 7 diatomic elements. gas 12 The properties of the representative elements are the only you need to know. 13 Four of the representative element groups have special names. Group 1Group 2Group 17Group 18 Alkali Metals Alkaline Earth Metals HalogensNoble Gases Most Reactive Metals Most Reactive Nonmetals Never Reacts 1 Valence Electron 2 Valence Electrons 7 Valence Electrons 8 Valence Electrons 14 Number of Valence Electrons for families of representative elements. 15 Nitrogen is in group 17 and all elements in this group have 5 valence electrons. Oxygen is in group 16 and all elements in this group have 6 valence electrons. 16 A full valence shell would contain 8 electrons. Hence the name of the rule Octet. 17 Lose valence electrons (+) Gain valence electrons (-) 18 The law of conservation of Matter/Mass You must have the same number of each element on the reactant and product sides of a reaction. 19 Valence Electrons are the electrons involved in chemical reactions! They cause chemical properties. 1 valence electron 20 Parts of a Chemical Reaction 2 Na + 1 Cl 2 2 NaCl Reactants: Na and Cl 2 Product: NaCl Coefficients: 2, 1, 2 Subscripts: The 2 in Cl 2 The Law of Conservation of Matter/Mass is why we must balance all Chemical Reactions! When balancing a chemical reaction you may CHANGE THE COEFFICIENTS BUT NEVER THE SUBSCRIPTS! 21 22 Synthesis Reaction There are two reactants and one product. Is reverse of decomposition. General Form: A + B AB 23 Balanced synthesis reaction of water. This reaction is used to push the space shuttle into orbit! 24 Decomposition Reaction There is one reactant and two or more products General Form: AB A + B 25 Decomposition Reaction 2H 2 O 2H 2 + 1O 2 Decomposition due to electrical current. Electricity symbols 26 Single Displacement/Replacement Reactions. Reactants: ionic compound and metal. Products: ionic compound with metal displaced by reactant metal and the displaced metal. 27 Examples of Single Displacement/Replacement Reactions General Form: A + BC AC + B 1MgCl 2 + 2Na 2NaCl + 1Mg These reactions only occur in aqueous solution. 28 The iron in the knife is replacing the copper that is in solution which causes copper to form on the surface of the knife. Copper deposits on the knife as the iron dissolves into solution 29 Double Displacement/Replacement Reactions. These reactions have two ionic compounds and the products are two new compounds with the negative ion of each reactant switching places. 30 Examples of Double Displacement/Replacement Reactions. General Form: AB + CD AD + CB Note how the negative ions switch places. 2NaCl + 1CaBr 2 2NaBr + 1CaCl 2 These Reactions Only Occur In Aqueous Solution One of the products is not soluble in water and forms a precipitate 31 Copper Hydroxide is not soluble in water and therefore precipitates 32 Combustion The reactants will always be fuel + Oxygen and the products will always be carbon dioxide and water. 33 Main Topics Discussed The Law of Conservation of Matter The number of reactant atoms must equal the number of Product Atoms! Valence Electrons are the only electrons involved in chemical reactions There are five basic chemical reaction types Chemical reactions must be Balanced by changing the Coefficients! The Subscripts can Never Be Changed! 34 Ionic & Covalent Element Atom Molecule Compound Valence electrons Cation Anion Oxidation number Lose electrons Gain electrons Metals Nonmetals Ionic bond Covalent bond Law of definite proportions Chemical formula Chemical bond Covalent compound prefixes 35 The two types of bonds/compounds 36 A full valence shell of electrons would contain 8 electrons and have the same total number of electrons as one of the noble gases. 37 The movement of valence shell electrons controls all chemical properties/reactions! This example shows 3 valence shell electrons. 2 electrons in 1 st energy level 3 electrons in 2 nd energy level 38 Ionic Bonds Metal will lose electrons and form a cation (+). Nonmetal will gain electrons and form an anion (-). Ionic bonds combine metal & nonmetal Overall charge of ionic compound must be zero! 39 Ionic Bond Formation. Metal gives up valence electrons (cation). Nonmetal takes valence electrons (anion) 40 Covalent Bonds Share valence electrons therefore no ions. It is difficult to predict their formulas. 41 Ionic Bonds Form between a metal & nonmetal The metal always loses valence electrons to the nonmetal The metal will form a cation The nonmetal will gain the valence electrons to form a anion Covalent Bonds Form between two nonmetals. No ions are formed. The valence electrons are shared. There is no predictable charge for the nonmetals in a covalent compound. You will not be able to predict the formula for these compounds. 42 Ionic Compounds Composed of Representative Elements The Law of Definite Proportions Formulas for ionic compound are predictable because of predictable charges of representative elements. Always have same proportions 43 Ionic Compound Formulas Look Back at Slide 17 for Group Charges 44 What is the function of waves? They are used to transfer energy. 45 There are two types of waves that transfer energy. Sound (Mechanical) Light (Electromagnetic) 46 How fast will these two types of waves transfer energy? Electromagnetic waves travel at the speed of light (visible light is just a small portion of the spectrum) 3.0 * 10 8 m/s Sound waves (mechanical) require a medium and travel at different speeds depending on the medium. 47 Key terms associated with sound. Wavelength Longitudinal Rarefaction Compression Medium Density Amplitude Hertz Mechanical Condensation Transverse 48 How fast can sound travel through different mediums? The speed of sound depends on the density of the medium. Travels slowest in gasses because it has the lowest density. It travels faster in liquids because they are denser. It travels fastest thought solids because this is the material with the greatest density.. 49 Examples of the speed of sound in different medium. Gasses Oxygen 316 m/s Air 343 m/s Liquids Water 1482 m/s Ethanol 1162 m/s Solids Glass 5960 m/s Copper 5010 m/s 50 Wave diagrams 51 How does this relate to what I hear? The amplitude is related to the volume. The frequency is related to pitch. Hertz (Hz) is the number of cycles per second. Humans can hear any sound between 20 Hz to 20,000 Hz Dogs can hear up to 35,000 Hz Hertz are the units for frequency 52 53 The two types of wave interference 54 Another look at Interference 55 The Doppler Effect 56 Introduction to Electro Magnetic (EM) Waves 57 The parts of an EM wave. The as represent Amplitude as peak or trough. The symbol gamma () represents wavelength. 58 The Speed Of Light (EM) Spectrum The speed of EM radiation in a vacuum (space) is 3.00 x 10 8 m/s You can assume that this is the speed limit of the Universe! 59 Trends of the EM Spectrum 1.The greater the frequency of the wave the greater the energy of the wave (gamma rays have the greatest frequency/they have the greatest energy) 2.The lower the frequency of the wave the lower the energy of the wave (radio wave has a very low frequency/they have a low amount of energy) 3.The greater the frequency the smaller the wavelength and the greater the energy 60 Reflection The angle the light hits the mirror is the angle it is reflected 61 Refraction The light wave bends as it goes from medium one to medium two 62 EM Waves Can Interact by Either Adding Together to Increase a or Decrease a. 63 Diffraction is the Property of Light Which Allows it to Bend Around Objects Which Limits the Size of an Objects Shadow 64 The Three Units Below are Related by Ohms Law. Voltage (E) units are voltage The voltage of the battery in a DC system will be given. Resistance (R) units are Ohms The total resistance in a series circuit is the sum of all the resistors. The total resistance in a parallel circuit is the sum of 1/R. Current (I) units are Amps 65 These are two simple examples of series and parallel circuits 66 In Parallel Circuits the total resistance is 1/R 1 + 1/R 2 + 1/R 3 67 Series circuit the total resistance is the sum of all the resistors. R 1 + R 2 + R 3