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volume, etc. Chemical Changes Result in new substance combustion, reduction, decomposition -Law of Conservation of Matter: matter cannot be created or destroyed - However, matter undergoes physical and chemical changes constantly, these changes are called movement of matter - Energy is the ability to change matter. - Energy exists in several forms: potential energy Cenergy due to the position of the object), Kinetic energy Cenergy due to the motion of the object), heat energy, electrical energy, etc. -Laws of Conservation of Energy: energy is converted from one form to another, but it can't be created or destroyed. Measure of Matter - in science, S1 units are used. Physical Quantity Mass length time temperature Amount Electrical current Name of unit kilogram meter second Kelvin Mole Ampere Abbreviation Kg sec K mol amp Scientific Notation used because in chem numbers are really big or small N.10* A aroitlusto bro cromates M Dimensional Analysis out b - units are multiplied together or divided into each other along with numerical values, an - equivalent units cancel each other out Conversion factors Length Mass as Volume 1 mi = 1609.3m... 1m₁ = 1760 160-asund taposol Line 2.54cm can wet putate mo bol 1kg = 2.2051bae gift g - 11b = 453.69 Igal = 3.78.L 1L = 1.06qt 1f1²³ = 28.321) برگزار اوارد 1-2 45402 VISK + pingut rom Measurements and Calculations The data you collect and your chemical analysis need to be both quantitive and qualitive measured quantities. Must be mL 3 2 1e 2.3mL Significant Figures - relate to the precision of a measurement. You are stating how precise your measurement is - guess one past the smallest measuring increment always ♥ THIDAY + accurate precise 2.30mL Add/Subtract The result has the least # of sig figs after the decimal 3.69 7.429 11.0% non-numerical (color change) close to the actual value - obtain same (similar) results. throughout different trials, • non-zero numbers sandwiched zeros trailing zeros leading zeros - The data with the 3 sig figs shows the measurement was more precise *For calculations with more measurements, you are only as precise as your least precise tool Multiply/Divide The result has the least # of sig figs 0.150 kg 8.3°C 4.18 KJ 5.201XKJ . always significant always significant Significant if there's a decimal neversignificant relative atomic mass C Atoms: The Building Blocks of Matter An atom is composed of a nucleus containing protons and neutrons, and electrons residing outside of the nucleus D Particle Proton (pt) neutron(n) Nucleus electron (e) Outside 12 Location Charge Mass Nucleus Lamu 1+ 0amu e Mass number (protons + neutrons) C-symbol 6 Alomic number C#protons or electrons) mass number of isotopes O 1- ( Isotopes are atoms with same number of protons (and electrons), but different numbers of neutrons. X1 # of protons #of protons = = Atomic Weights • Relative atomic weight shows how many times larger is atomic mass of the given element compared with the atomic mass of the other element. Accepted as units. Relative atomic weights are measured in atomic mass units Camu) Atomic weight is calculated as weighted average of masses of the elements natural occuring isotopes percent, abundance + isotope 1 100 Atomic # # of electrons -An atom is electroneutral • Mass # = Atomic# + # of neutrons mass number x of isotope2 percent abundance) C C Periodic Table of Elements the rows are called periods columns are groups, elements in the same group have similar chemical properties. • Periodicity is a repeating pattern of reactivities in the chemical properties of elements ↑ •electronegativity increases • lonization energy increases Electron affinity increases • Electronegativity increases lonization increases • Electron Affinity increases 6A 7A 8A Groups in the Periodic Table Group Name Elements 1A Alkali (M) Li, Na, K, Rb, Cs, Fr 2A Alkaline (M) Be, Mg, Ca, Sr, Ba, Ra Lou atomic radius increases atomic radius increases ↓ Chalogens Halogens *Think opposite for finding decreases 0, S, Se, Te, Po F, Cl, Br, I, At Noble gases He, Ne, Ar, Kr, Xe, Rnl 100 Molecules and Molecular Compounds -A molecule is an assembly of atoms bound together. by chemical bonds Molecular formula shows types and numbers of atoms in One molecule of a substance The subscript to the right of the symbol of an element tells the number of atoms of atoms of that element in one molecule of the compound. - Molecular compounds consist of molecules made of atoms of two or more different elements. Diatomic molecules of Elements • Some of nonmetals naturally form Diatomic molecules Ex: Hydrogen: H₂ Nitrogen: N₂ OxygenO₂ Flourine: F₂ Chlorine: Cl₂ Bromine: Br₂ lodine: I₂ Types of Molecular Formulas Empirical formulas give the lowest whole number ratio of atoms in a compound • Molecular formulas give the exact number of elements in a compound. Empirical formula →g. 30.45% N NxOy 2 Convert q % composition by mass: J Assume 100g total 30.459 N, 69.5590 -7 mol 1 mol N (30.45gN) T4 9N) = 2.18 (69.559 0) (160) = 4.35 H 69.55% 0 (x and y = mole ratio) 3 Divide all by smallest 4.35 2,18 N₁ → mol mm element mm compound 2.18 2.18 N₁0₂ Molecular formula: Divide the molar mass of the compound by the empirical formula value. Multiply subscripts by the Whole number found in the last step. = 2,01 = 0₂ C Nuclear Chemistry A Study of the nucleus of atoms and related reactions Radioactive Decay - When chemicals have unstable nucleus, the chemicals Will naturally try to stabilize itself - The natural conversion of an unstable chemical to a more. Stable one is called Radioactive Decay electron neutron proton 47- Nucleus Arrangement of Electrons in Labeling Electrons in atoms • Electrons are the most important subatomic particles of the atom. Atoms - When atoms interact with each other, it's the electrons that do all the interacting. The amount, energy, and location of electrons with an atom helps chemists to predict the chemical, physical, and electrical behaviors of substances. Electron Configuration is a summary address book of where all the electrons are located around a nucleus. the nucleus.. - The large number in front of the letter is the energy level - Energy level represents the distance the electrons are from • Electron Configuration Breakdown 15² 2 1-5 2- S, P 3-5, p, d Yon-s, p/d/f -Each energy level has a specific amount of orbitals. -orbital is the 3D area the electrons are hanging out around the nucleus. Each orbital can only hold a certain number of electrons max. S = 2e max p=be² max d = 10emax f= 14e¯ max Writing in Electron Configuration 1. Identify the given element and its atomic number 2. Write the energy level ( period/row) 3, Following the energy level, write the sublevel Cs, p, d, f) 4. Determine how many electrons are in that energy level and Sublevel as superscripts. C Chemical Bonding Properties of Covalent Compounds -The atoms of covalent compounds or molecular compounds are connected via covalent bonds - Because covalent bonds are weaker than ionic bonds, covalent compounds typically have lower melting and boiling points. - Covalent compounds usually don't dissolve in water unless they're polar. Octet rule- atoms will gain/lose / share e to have full valence shell Metals tend to lose e, become cations nonmetals gain e, become anions ionic bonds form between metals and nonmetals Bonds tend to be strong, compounds weak Transition metals - use roman numerals CUCL = copper (1) chloride CuCl₂= copper (H) chloride Jonic Compounds transition include romannumerals binary -Single-charge - "metals" nonmetal (ide) - charge of metal Jonic Compounds transfer e metal & nonmetal VS Polyatomic "ite","ate" Covalent Share e at nonmetals []} VSEPR Theory (Molecular Shapes) A = the central atom, X = an atom bonded to A, E = a lone pair on A Note: There are lone pairs on X or other atoms, but we don't care. We are interested in only the electron densities or domains around atom A. Example Bond Bonded Lone Atoms Pairs 1 Angles 0 180 Total Generic Domains Formula AX 1 2 3 4 AX₂ AXE AX3 AX₂E AXE2 AXA AX₂E AX₂E2 AXE3 Picture A-X X-A-X X A- X A X J 2 1 3 2 1 4 3 2 1 0 1 0 1 2 0 1 2 3 Molecular Shape Linear Linear Linear Trigonal planar Bent Linear Tetrahedral Trigonal pyramid Bent Linear Electron Geometry Linear Linear Linear Trigonal planar Trigonal planar Trigonal planar Tetrahedral Tetrahedral Tetrahedral Tetrahedral H₂ CO₂ CN AlBr3 SnClz 0₂ SiCl4 PH3 SeBr₂ Cl₂ Hybridi -zation S sp Sp² D3 sp 180 120 109.5 Generic Total Domains Formula 5 AX5 6 Notes AX₂E AX3E₂ AX₂E3 AX6 AXE AX4E₂ Picture ...X X- * * Zx x L X S X * Bonded Lone Atoms Pairs 5 0 3 2 6 5 4 1 2 3 0 1 2 Molecular Shape Trigonal bipyramid See Saw T shape Linear Octahedral Square pyramid Square planar Electron Geometry Trigonal bipyramid Trigonal bipyramid Trigonal bipyramid Octahedral Octahedral Example Hybridi -zation AsF5 Trigonal bipyramid BrF₂ Octahedral SeH4 IC13 SeCl6 IF5 XeF4 sp³d sp³d² Bond Angles 90 and 120 90 1. There are no stable AXE4, AX3E3, AX₂E4 or AXE, molecules. 2. All bonds are represented in this table as a line whether the bond is single, double, or triple. 3. Any atom bonded to the center atom counts as one domain, even if it is bonded by a double or triple bond. Count atoms and lone pairs to determine the number of domains, do not count bonds. 4. The number of bonded atoms plus lone pairs always adds up to the total number of domains. A represents a change or difference Polar molecules -molecules in which one end of the molecule is slightly positive, while the other end is slightly negative. Lewis Dot Structures valence electrons- outermost electrons/highest energy Steps to draw 1. Total the valence electrons 2. Draw skeleton Carrangement of them bonded together) 3. Subtract 2 electrons per bond 4. Satisfy octet rule 5. If necessary, farm double bonds CCI 1. 100 +467) = 32e" 2. 0₂ mono di tri :Ö 2 یہ ہر 3 tetra - 4 5 penta hexa 6 hepta - 7 octa 8 nona - 9 deca - 10 cl Ö: 3. CIE CIE :CI CI: Exceptions to octet H wants just 2 e Be fine with Ye- B fine with be Formal Charge FC= #valence e² - # nonbonding e² - # bonds Want FC=0. **** Bond Polarity - difference in electronegativity A EN = >4 = Polar A EN=<.4 = Nonpolar Vector + 10mph (forwards) -10mph (backwards) magnitude and direction Molecule Polarity · In order for molécule to be polar, need at least one polar bond 8=c=6 Dipoles Cancel each other out Molecular Shapes Chemical Formulas and Compounds Macro-Scale Pertinence: what we observe on the macro-scale is happening on the atomic level and we represent that with Symbols 0 . -Nonclemature: the deuising or choosing of names for things - Stock system. • 0²- 34 Fest . • Lit Iron (II) chloride • FeCl3 Metal Cation lons Monoatomic lons 2+ Ca²+ Prefix System Carbon dioxide CO₂ Non-Metal Cation Stock System Clonic compounds) 1. write the symbol for the ions with charges 2. Cross over 3. Check charges. Polyatomic lons OH • CO3² • • . 2- lonic Compounds Cation Croman numeral) anion-ide NODOWN, NH₂ Compounds Nonmetal Cation Molecular Compound Uses prefixes to indicate the number of atoms G 1 5/14/23, 8:31 PM Oxidation Numbers Oxidation Numbers It is often useful to follow chemical reactions by looking at changes in the oxidation numbers of the atoms in each compound during the reaction. Oxidation numbers also play an important role in the systematic nomenclature of chemical compounds. By definition, the oxidation number of an atom is the charge that atom would have if the compound was composed of ions. 1. The oxidation number of an atom is zero in a neutral substance that contains atoms of only one element. Thus, the atoms in O₂, O3, P4, S8, and aluminum metal all have an oxidation number of 0. 2. The oxidation number of simple ions is equal to the charge on the ion. The oxidation number of sodium in the Na* ion is +1, for example, and the oxidation number of chlorine in the CI' ion is -1. 3. The oxidation number of hydrogen is +1 when it is combined with a nonmetal as in CH4, NH3, H₂O, and HCl. 4. The oxidation number of hydrogen is -1 when it is combined with a metal as in. LiH, NaH, CaH2, and LiAlH4. 5. The metals in Group IA form compounds (such as LigN and Na₂S) in which the metal atom has an oxidation number of +1. 6. The elements in Group IIA form compounds (such as Mg3N2 and CaCO3) in which the metal atom has a +2 oxidation number. 7. Oxygen usually has an oxidation number of -2. Exceptions include molecules and polyatomic ions that contain O-O bonds, such as 0₂, 03, H₂O2, and the O₂2- ion. 8. The elements in Group VIIA often form compounds (such as AlF3, HCl, and ZnBr₂) in which the nonmetal has a -1 oxidation number. 9. The sum of the oxidation numbers in a neutral compound is zero. 3.19 H₂O: 2(+1) + (-2) = 0 10. The sum of the oxidation numbers in a polyatomic ion is equal to the charge on the ion. The oxidation number of the sulfur atom in the SO42- ion must be +6, for example, because the sum of the oxidation numbers of the atoms in this ion must equal -2. 11. Elements toward the bottom left corner of the oxidation numbers than those toward the oxidation number in SO2, for SO: (+6)+ 4(-2) = -2 xidation Numbers . Oxidation Numbers show the general distribution of electrons • Ionic Compounds : Molecular Compounds: Electrons shared. Guidelines in a compound 5/14/23, 8:31 PM electrons are transferred Pure elements have oxidation numbers of O number like its charge. The more electronegative element has an oxidation Fluorine is always -1 Oxygen is almost always-2 Hydrogen is t1 or -1 sum = 0, or sum= charge of polyatomic ion. The Empirical Formula Empirical Formulas are expressed Molecular Formulas show I how many atoms of each elementare in the molecules) C&H ₂O CH₂O 2. H₂O₂ HO √3. C₂ H₂O4 > CH₂O Calculate the percent composition of each element of ethano!! Percent by mass of each element present in a compound as the smallest possible whole # ratios of the elements in compounds. Percent Composition: The 1. Find the # of atoms in each element, 2. Find the molar mass H and multiply by if of moles Carbon = 12g/mol. 2mal = 24g Hydrogen= 1g/mol ·bral = 6g Oxgen = 16/mol • 1 mal = 169 2 of C 6 of H 1 of 0 H 1 H-C C-OH 1 1 HH 3. To calculate percent composition, divide molar mass of each element by that of ethanol and multiply by 100 How to determine the empirical formula being given the mass of each element of a compound? 1. check compound composition to be sure it's given in grams 2. convert from grams to moles with Imole/molar mass of substance 3. Calculate whole-number mole vatio. 4. Determine Subscripts. 5. Write Empirical Formula. % C = 24/46 *100 = 52% %/ H = 6/46 x 100 = 13% 1%/ 0=16146 x 100 = 35% How to convert from an empirical. formula to a molecular formula 1. Calculate the molar mass of the empirical formula. 2. Divide molecular mass by the empirical formula molar mass. 13. Multiply subscripts by this ratio. How to determine empirical formula of a compound from its % composition? 1. Check units of composition, Assume you have loo grams of the sample if it's in percentages. 2. Convert grams to moles 3. Calculate whole-number mole ratio 4. Determine Subscripts. 5. Write the empirical formula, Combined = mass of one mole of ethanol - ubg Chemical Equations and Reactions e Balancing Equations ut sinc • To show that mass is conserved; a chemical equation must show that the number of each type of atom must be the same. on both sides of the equation. You have to put coefficients in front of the Compound to balence, DO NOT CHANGE SUBSCRIPTS Coefficients must be lowest whole number ratio. STEPS create a chart with how many of each elernent you have on the reactants and products side. de a Start with elements that are on their own and aren't se oxygen or hydrogenal ne bon) me • Write in the coefficient and then update the chart •Go to the element that needs balancing with • Repeat until the number for each element are equal on both sides Types of Reactions - Synthesis & Shotokan api keni mend - Reaction in which two or more reactants combine to form a single product 7.Decompositions HasaISUDIG ASAL - Reaction in which a single compound breaks down to form two or more new substances. I H Combustion / kum A to t - Reaction in which one ion displaces another to form a new to taken to Framsalied Double-replacement // METAS -Reaction in which two onic compounds exchange ions to form new products. - Reaction of a substance with oxygen - Single-replacement I compound. Synthesis: two or more substances form a new compound. A+X-AX Ba+F₂ BaF₂ Ex. 2Mg +0₂2MqO 2Na+Cl₂2NaCI Lithium + oxgen Lithium Oxide Calcium + chlorine →→ Calcium chloride Strontium + oxygen → 4Li +0₂2Li₂O Ca + Cl₂ → CaCl₂ intium oxide 25r+0₂ → 2SrO Decomposition: One compound forms two or more similar compounds AX→ A+X Ex. 2H₂O2H₂ + O₂ 2HgO 2Hg + O₂ Decomposition reactions that involve specific polyatomic ions break apart in predictable patterns: Metal carbonates decompose to form metal oxides and carbon dioxide s7 Cao t CaCO3 CO₂ Metal chlorates decompose to form metal chlorides and diatomic oxygen. 2KCIO32KC1+30₂ Metal hydroxides decompose to form metal oxides and water Ca (OH)₂ CaO + H₂O Single Replacement: One element replaces a similar element. within a compound, AX+B AB + X The element that is replaced MUST have the same type of charge. (tor) as the element replacing it. When replacing metals or hallogens, be sure to refer to the Activity Series first. Replacement of a metal by a more active metal: 2A1+3Pb(NO3)2 →2A1(NO3)3 + Pb Ag+ Pb(NO3)₂ No Reaction Replacent of a halogen by a more active halogen: 2KBr + Cl₂ → 2KCl + Br₂ KBr + 1₂ No Reaction Metals Activity Series Halogens Li CI Chlorine K F Fluorine Ba Barium Br Bromine lodine Ca Calcium Na Sodiumras Mg Magnesium Al Aluminum C Cabon Zn Zinc Lithium Potassium Fe Iron Ni Nickel Sn Tin .Pb Lead. H Hydrogen Cu Copper Hg Mercury Ag Silver Au Gold 1Pt Platinum Oxidation-Reduction Reaction Credox) -type of chemical reaction that involves a transfer of electrons between two species. - any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron. (charge) reduced Oxidized Single-Replacement: always redox Double- Replacement: never redox Synthesis: Sometimes redox Single-Replacement Redax Examples: 2A1+3Pb(NO3)₂ 2A1+3Pb+3CNO3)2 2A1° +3P6¹2 42 composition: Sometimes redox Combustion: always redox Fe + Sn CC₂H₂O₂)2 Fe + Sn²+ C₂H₂O₂ - Fe + Sn → 3Pb + 2A1³+ reduced 3Pb+ 2AICNO), -3Pb²° + 2A1³² +2CNO₂) Oxidized Sn + Fe CC₂ H₂O₂)₂ Sn° + Fe²+ C₂ H₂O₂ Sn° + Fe ²0 Double-Replacement Reaction: The ions of two compounds exchange places to form two new compounds, AX+By Ay + BX → The positive ion from the first compound combines with the negative ion from the second compound and vice-versa. General Solubility rules Contains alkali, ammonium acetate, nitrate chlonde, bromide, iodide Sulfate Sulfide, hydroxide ferrocyanide chlorate, pechlorate. Solubility? Soluble Soluble saluble Soluble Not soluble Not Soluble Soluble most other anions Not Soluble alkali + NHy Soluble To judge whether double-replacent reactions will occur, we need to know what kinds of ionic compounds form precipitates. For this, we use solubility rules, which are general statements that predict which ionic compounds dissolve and which ones aren't. Steps 1. Do swap, Consider charges. 2. Balance reaction. 3. Determine if reaction occurs -Classify products phases - all ag = no reaction. Need 1 solid, liquid, or gas. 4. Net ionic Exceptions Ag, Pb, Hg Ph.Hg alkali+ NH Soluble alkali + NHy soluble Net ionic equations: The aforementioned ionic equation. without spectator ions Spectator ions: ions that don't combine into a solid. Double-replacent reaction examples: 3 PbCNO₂), 2AICI, (aq) (aq) 3Pb+ Cl → 3PbCl₂ 3PbCl₂ + 2Al(NO₂), (aq) Ca I + Ag CrO₂ Ag I Ca Cr Ou → (5) Ca + CrO₂ CaCrO4 Combustion Reaction: Hydrocarbon reacts with Oxygen gas, releasing heat and light, and carbon dioxide and water. Cx Hy CO₂) + O₂ ex: C₂H₂ +50₂ CH,O + O2 →CO,H,O 3CO₂ + 4H₂O + CO + H2O. -Factors affecting reaction rate: 1 Reactant Nature RENESE Unstable bonds break easily, unlike stable bonds >lonic reactants react fast at room temp ▸ covalent reactants react slow at room temp Homogenous Reaction: reactants in same phase Heterogenous Reaction: reactants in different phase 2) Surface Area More surface area = more collisions, higher rate 3) Temperature: average Kinetic energy Faster particles = more collisions, more energetic collisions 4) Concentration • Higher M = more collisions Stufft ↑ collisions Space Reaction Kinetics 。 Catalysts • Catalyst: Substance that speeds up a reaction. lower activation energy 1.7 Rate change time - Reaction Rate : rate at which reactants turn to products •Expressed as concentration of reactant consumption or product formation D When using reactants, (-) is used to show a decrease in concentration." AR/P A time Average reaction rate = -Speed can tell us a lot about Chemistry collision theory • reaction mechanisms • also use kinetics to speed or slow reactions - Collision Theory: Molecules must collide with each other in order to react (exchange e') • reactants must collide with Sufficient speed and correct orientation