Study Guide for General Chemistry (CH 185)
Study Guide for General Chemistry (CH 185) CH 185 - 02
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This 18 page Study Guide was uploaded by Jasmine Hamilton on Thursday October 15, 2015. The Study Guide belongs to CH 185 - 02 at Southeast Missouri State University taught by Marcus R Bond (P) in Fall 2015. Since its upload, it has received 101 views. For similar materials see General Chemistry in Chemistry at Southeast Missouri State University.
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Date Created: 10/15/15
Study Guide for General Chemistry Midterm 0 Measurement amp Calculations CH2 amp Appendixes IIII good review 0 Numerical Measurements express three things i Numerical value ii Units of measurement iii Level of precision 0 Units of Measurement i Differ by quantity measured size and system ii Scienti c community uses metric system powers of 10 iii Metric units are distinguished by a pre x that designates the power of ten used Note Pre xes commonly used in Chemistry It is crucial to memorize these Metric Prefix Power of 10 Abbreviation kilo 1 X 10quot3 k deci 1 X 10quot1 d centi 1 X 10quot2 c miIIi 1 X 10quot3 m micro 1X 10quot6 p nano 1X 10quot9 n pico 1 X 10quot12 p femto 1 X 10quot15 f Note Be able to write down simple equalities that relate the metric unit with the pre x to the metric unit without the pre x 0 Terms 139 Mass measure of the amount of m present in an object base unit kg ii Matter anything that has mass and occupies space iii Weight measurement of the force exerted by gravity on an object of a given mass Note A mass of 1 kg corresponds to a weight of 2205 lb 0 Base and Derived Units of Measurement i Temperature 0 Measure of amount of average kinetic energy of the atoms or molecules in matter 0 Measured in Kelvin K 0 Equations 0 C OF320F50C9OF o 0F OC9OF50C320F o KOC27315 Notes These are basic degrees for freezing and boiling points for each scale These are important to know especially for checking yourself Freezing Point Boiling Point 0 C 100 C 32 F 212 F 273 OK 373 OK 0 Volume 0 Measures how much space occupies matter O V Width X length X height 0 SI unit is cmA3 o A more practical unit for volume is the liter L EX 1 L1 dmA3 1m31 m3 l mLl cm3 lm3l m3 l L 0 Density 0 Ratio of mass to its volume dmv 0 d density 0 m mass 0 V volume 0 SIderived unit kilogram per cubic meter kgm3 o More common units gcm3 or gmL solids and liquids gL gases 0 Terms i Accuracyhow close a measurement is to the true value of the quantity being measured ii Precision how closely two or more measurements of the same quantity agree with one another Note Random error in measurements is always present and affects the precision The effect of random error can be reduced by taking the average of several measurements of the same quantity 0 Signi cant Figures i Digits in a measurement that are known with some or complete certainty The more significant digits in a measurement the higher the level of precision ii Least significant digit rightmost digit about which there is some but not complete uncertainty 0 Rules 1 All zeroes written to the left of the first nonzero digit are placeholder zeroes and are not significant 2 Trailing zeroes in a number without a decimal point 35000 for example are assumed to be wsignificant unless otherwise stated Examples 673 K 3 sig figs significant figures 6055 s 4 0006 g 1 3000 mL 4 40000 people 1 00001200 mol 4 Calculations with Sig Figs Rules 0 In and the number of digits to the right of the decimal point is determined by the lowest number of digits to the right of the decimal point in the original operation 0 In multiplication and the number of sig figs in the product or quotient is determined by the smallest number of sig figs in the original operation 0 Numbers that are de ned or cardinal numbers those obtained by counting are exact numbers and have an in nite number of signi cant gures Examples 249362 41 63498 457 Here s why this answer is 3 sig figs 249362 41 this is addition so the product considering sig figs will not have anything behind the decimal so the least significant digit will be 299362 Divide this answer which makes the least amount of sig figs to be three so the answer is 457 O Chl Atoms Intro to Chemistry a Properties of Matter i Extensive property a property Whose value depends on the amount of matter present 1 Ex mass volume Note determines how much ii Intensive property a property Whose value does NOT depends on the matter present 1 Ex Temp color Note determines What kind iii Physical property can be observed Without changing the identity of a sample of matter Ex color temp mass volume iV Chemical property can only be observed by changing the identity of a sample of matter Ex paper burns iron metal rusts b Process of Matter Undergoes 1 Physical Process the identity of matter does not change Ex melting boiling vaporizing and dissolVing 2 Chemical Process or Chemical Reaction identity of matter changes Ex paper burns rust Ex questions Is density a physical or chemical property Extensive or Intensive It is a physical property but intensive Why When you double the mass amp volume the density comes out the same so density is not dependent on the amount of matter c Classi cation of Matter 1 Substance matter that has a constant amp de nite composition 2 Mixture matter that contains two or more substances combined so that each substance retains its identity 0 Homogenous or solutionuniform composition throughout O Heterogenous mixture nonuniform mixture throughout chunky O Elementsubstance that can not be broken down into a simpler substance 0 Compounds two or more elements that are united chemically d Periodic Table l Periods are the rows Groups are the columns usually share the same properties if in the same group a Name of Groups i 1st column or Group IA is the alkali metals ii 2A Alkaline Earth Metals iii IBcoinage metals Cu Ag Au iv 7Ahalogens V 8Anoble gases 2 Stairstep Line a left of the line are metals Al is a metal even though it touches the line b right of the line are nonmetals c if touching the line than elements are metalloids or semimetals except for Al aluminum 3 Chemical Properties of MetalsN on Metals a Metals tend to lose electrons to form cations b Nonmetals tend to gain electrons forming anions 0 Laws Theories Experiments and People 1 Law of Conservation of Mass matter or mass cannot be created or destroyed 2 Law of De nite Proportions a chemical compound always contains the same proportion or composition of elements by mass 3 Dalton s Atomic Theory a Matter is composed of atoms and retain their identities during reactions b All atoms of a given element are identical in size mass and chemicals properties c Ratio of the number of atoms of any two element is either an integer or a simple fraction d A chemical reaction involves only the separation combustion rearrangement of atoms 4 Cathode Ray Tube Experiment made by J J Thompson that found the electron 5 Millikan Oil Drop Experiment made by Robert Millikan and deduced the charge for a single electron 6 Gold Foil Experiment a Performed by Ernest Rutherford b Discovered that the atom has a positively charged nucleus majority of the atom is empty space most of the mass is concentrated in the nucleus and the electrons are dispersed in space 7 Antoine Becquerel a Discovered radioactivityspontaneous emission of radiation b Three types i Alpha rays particles that carry a 2 charge amp have almost the same mass as a helium atom ii Beta rays are like electrons iii Gamma rays are a form of light like Xrays 8 Particles a Electron has a negative charge 1 b Proton has a positive charge in nucleus has a mass of about 1 amuH atom the atomic number of an element is the number of protons c Neutron discovered by James Chadwick slightly larger than a proton neutral charge 0 accounts for missing mass of the nucleus 0 Ions Moles and Energy a An ion is an atom or molecule that gains or loses electrons to gain an overall positive or negative net charge i Cation an atom or molecule that has lost electrons to form positive charge ii Anion an atom or molecule that has gained electrons Note Metals tend to lose electrons When they react with nonmetals Nonmetals tend to gain electrons When they react with metals Charges 0 Group IA metal elements have 1 charge in reactions with nonmetal elements 0 Group IIA metal elements have 2 charge in reactions with nonmetal elements 0 Aluminum has 3 charge in reactions with nonmetal elements 0 Group VIIA nonmetal elements form anions with a 1 charge in reactions with metal elements 0 Group VIA nonmetal elements form anions with a 2 charge in reactions with metal elements 0 Group VA nonmetal elements form anions with a 3 charge in reactions with metal elements b The mole is the SI unit for the amount of substance The abbreviation for mole is mol Note Avogadro39s number 6022 X10A23 l Molar mass is the mass of one mole of a substance and is often eXpressed as a unit factor ratio in units of gmol EX 1 mole Al 26982 g Al simple equality relation unit factor ratio 26982 gmol Converting from grams to moles How many moles of lead are in 1000 g of lead 1000 g Pb 004826 mol Pb 2072 gmol What is the mass in grams of 127 moles of Ar 127 mol Ar39948 gmol 507 g HCl c Energy is the ability to do work or transfer heat 1 Kinetic energy is the energy of motion Equation Ek 12mv2 2 Temperature is the measure of thermal energy present in an object The higher the temperature the faster a given atom molecule or ion is moving 3 Heat q is the transfer of thermal energy from an object at higher temperature to an object at lower temperature 4 Potential energy is energy stored in an object gravitational potential energy m glz g981 ms2 5 Chemical energy is internal potential energy stored in an object by virtue of the submicroscopic positions of atoms molecules and ions bound together by attractive bonding forces Chemical energy can be released in a chemical reaction 6 Law of Conservation of Energy a Energy can be neither created nor destroyed in any process The total energy of the universe is constant 0 Ch 3 Quantum Energy a Terms i Traveling wave a periodic vibrational disturbance that travels and transmits energy ex water waves light ii Standing wave a periodic vibrational disturbance confined in a constant position contains energy ex plucked guitar string an electron in an atom iii Wavelength xi the distance between successive equivalent points of the wave units of m or nm commonly used for light iv Frequency the number of cycles pass a given point or occur in 1 second units of sl or Hertz Hz V Amplitude half the vertical distance between the crest and the trough b Thomas Young39s Double Slit Diffraction Experiment i Light is not observed to bend into its shadow because the wavelength of light waves is so small ii Must use small objects or narrow apertures to detect the wave properties of light iii Thus different colors of light must have different wavelengths c James Clerk Maxwell had shown that his laws of electricity and magnetism could explain light as a traveling electromagnetic wave and correctly predict the speed of light c ex c 300 x108 ms c Xv or M cv d Planck s Quantum Theory of Light i Light can only be emitted or absorbed in whole number multiples of a fundamental amount of energy known as a quantum Equantum h hck ii Light shining on the negative electrode will cause electrons to be emitted if it has a frequency at or above a certain threshold frequency iii If the light has a frequency below the threshold frequency no electrons are emitted iv For light with a frequency at or above the threshold frequency the more brightly the light shines the more electrons are emitted e Albert Einstein explained the photoelectric effect as follows i Light consists of particles that carry a quantum of energy Ephoton h hck ii When a photon of light at or above the threshold frequency hits an electron it can supply enough energy to break the attractive forces that bind the electron to the metal and the electron is emitted f Terms Cont l A continuous spectrum contains a broad range of wavelengths and frequencies of light absorbed or emitted by an object Examples sunlight incandescent or uorescent light 2 A line spectrum contains light emitted or absorbed only at certain discrete wavelengths and frequencies Example isolated atoms Just like light matter can have wave properties as well as particle properties g Debouglie s Law 1 The wavelength of a particle of matter can be calculated as khmv 2 The wavelength of a normal particle of matter a rock say is so incredibly small that we would not detect it 3 The wavelength of an electron is about the size of an atom so the wave properties of the electron are important in an atom A Quantum Numbers 0 Principal Quantum Number n o Characterized as the energy level and size of an electron ha 0 Has to be a whole number greater than or equal to 1 o The larger the value of n the more energy an orbital has and the larger the orbital itself o Angular Momentum Number I o Determines the shape 0 Can have a value from O to n1 0 Each value of l is signifies a particular letter which indicates the shape of the orbital I s orbitals are spherical I p orbitals are dumbbell shaped I d orbitals are mainly like four balloons I forbitals are mainly like eight balloons 0 Rules 0 For 1 I lO sublevel s I l1 sublevel p I l2 sublevel d I l3 sublevel t o For n nl the only allowed value of l is O ls n2 the allowed values of l are 0 1 2s 2p n3 allowed values of l are 012 3s3p3d n4 allowed values of l are Ol23 4s4p4d4f 0 Magnetic Quantum number m l O Determines the position or orientation of orbital O Gives the number of orbitals in a given shape 0 Has to be whole number value 0 Rules 0 10 s sublevel mlO 0 11 p sublevel ml lOl 0 12 d sublevel ml 21012 0 13 f sublevel ml 321012 Ex if 12 for instance this means there is 5 orbitals within 0 nA2 the number of orbitals Ex how many orbitals are in n3 3A2 9 orbitals 0 Quantum number ms O Determines the electrons spin 0 Is only two allowed spinsclockwise and counterclockwise o ms12 corresponds to spin up T o mslZ corresponds to spin down i note don t confuse ml and ms A good way to remember them apart is s is for spin B Electron Con guration 0 Terms 0 Ground state electron configurationlowest energy assignment of electrons to sublevels O Excited statea higher energy assignment of electrons O Orbital diagram graphical depiction of the exact assignment electrons 0 Rules Pauli Exclusion Principle 0 No two electrons in the atom can have the same set of four quantum numbers 0 If two electrons are assigned to the same orbital three quantum numbers are the same 0 At most two electrons can be in the same orbital but the spins must be different Ex 0 Rules Hund s Rule 0 Electrons are spread out in orbitals to give the maximum number of parallel signs 0 paramagnetic there is unpaired electrons attached to magnetic eld 0 diamagnetic all the electrons are paired slightly repelled by magnetic eld 0 Terms 0 noble gas core electrons are the innermost electrons of an atom correspond to the electron con guration of the nearest noble gas element 0 pseudonoble gas core is a noble gas core With any complete le of fl4 sublevels O valence electrons are the outermost electrons of the atom C Ionic radii and Ionization Energy 0 Trends with ionic radii O Ionic radii increases going down a column on the periodic table 0 More positive isoelectronic ions are smaller I Isoelectronic ions have a different number of protons but the same number of electrons I More positively charged ions of the same element are smaller 0 Trends with Ionization Energy 0 When moving up a columnacross a row the ionization energy gets bigger O Smaller the atom the greater the ionization energy note The elements in the far right comer of the periodic table have the highest ionization energies Examples of Electron Con guration Ch 5 Molecules and Compounds 0 Terms 0 Molecule is two or more atoms chemically bonded together Diatomic molecules have two atoms Homonuclear diatomic molecules contain two atoms of the same element 0 ex H2 Heteronuclear diatomic molecule contains 1 atom of each different element ex HCl Polyatomic molecules contain more than two atoms usually from different elemen ex C02 0 A chemical formula uses chemical symbols numbers and sometimes other symbols A molecular formula uses right subscripts to express many atoms of each element A structural formula uses lines and chemical symbols to express arrangements and connections between atoms 0 Isomers have the same molecular formula but different geometrical arrangements O Isomers have the same composition but are different from one another in their properties 0 Allotropes are different chemical forms the same element 0 ex dioxygen O2 0 Polyatomic ions are molecules that have gained or lost electrons to require a speci c charge 0 Common polyatomic ions De nitely MEMORIZE I PO43 Phosphate CN391 Cyanide CO3923 Carbonate NH1 4 Ammonium SO3924 Sulfate OH 1 Hydroxide I NO39l3 Nitrate o The formula unit of an ionic compound is the simplest Whole number combinations of electrons so that it is neutral 0 ex Na1 amp C1391 NaCl 0 A1339 amp F391 AlF3 Note To balance charges just switch charges of elements and use them as subscripts ex NH l4 amp PO3394 NH43PO4 0 Molecular mass the average mass calculated by adding average atomic mass of all atoms in the formula 0 Ex Molecular mass of SF6 3207amu S 6900 amu 14607 amu 0 If the molecular mass is 18016 amu than find how much in percentages Hydrogen and Oxygen is in the compound I H 201618016 x100 1119 I O160018016 x1008881 0 Formula mass same as molecular mass but this is generally used for ionic compounds 0 Ex Execute problems the same as molecular mass 0 Empirical formula a type of chemical formula that expresses the composition of a molecule or ionic solid in its simplest form 0 Ex Molecular Empirical N204 N02 0 Converting composition to empirical formula 0 Ex Find the empirical formula of catechol if the percent composition is 6545 C 549 Hand 2906 0 0 Answer For 100g of catechol there are 6545 g of C 549 g of H and 2906 g of 0 moles C 6545g120l lgmol 2l6l816 3 moles H 549glOgmol 549l8163 moles O 2906gl6 gmol l816l816 1 Ratio ofmoles of CHO is 331 O The empirical formula should be C3H3O 0000 Note You are dividing by the atomic mass of each element afterward you divide by the smallest amount of moles to find the whole numbers for the ratio and formula 0 Finding the Molecular Formula when given the Empirical Formula and molar mass 0 Ex Catechol empirical formula C3H3O has an experimental molar mass of 110 gmol What is its molecular formula 0 The ratio of experimental molar mass to empirical formula mass is expressed llOgmol 5506gmol 2 estimation All subscripts in the empirical formula are multiplied by 2 molecular formula C6H6O2 Naming Molecular and Ionic Compounds 0 Naming Molecular Covalent Compounds nonmetals I Binary Molecular Compounds 2 atoms 0 most metallic is listed first and the first name is stated The second element will be named with its stem and an ide suffix 0 Ex HCL hydrogen chloride 0 Binary compounds use greek prefixes to state how many atoms are in a given element 0 Ex CO carbon monoxide O N207 dichlorine heptoxide o Naming Ionic Compounds metals and nonmetals O Binary Ionic Compounds Nonmetal anions take the ide suffix No greek prefixes I Ex Kzse potassium selenide O Ionic compounds containing polyatomic ions 0 EX NH4Cl ammonium chloride 0 Stock System of Nomenclature 0 Use t when a particular metal element is known to form two or more cations with different charges The charge of the metal cation is written in Roman numerals after the name I EX FeCl3 ironIII chloride I FeCl2 ironII chloride Note This is done more often with transition metals because they don t have de nite charges usually 0 Chemical Bonding O Ionic bonds result from the attractions between oppositely charged ions that arise when valence electrons are completely transferred from one atom or molecule to another Covalent bonds result when valence electrons are shared between atoms of a molecule or polyatomic ion Polar covalent bondsthe bonding pair electrons are not shared equally Lewis dot symbols use the four sides of the chemical symbol of a main group atom to show valence electrons represented as dots I Octet rule main group atoms tend to react until they are surrounded by 8 valence electrons except for Hydrogen that only needs 2The octet rule is obeyed by atoms gaining losing or sharing valence electrons Examples of Bonding 0 Formal charge is the charge an atom in a Lewis structure would have if all bonding pair electrons are divided evenly between the bonding atoms For a given atom in a Lewis dot structure formal charge number of valence electrons number of lone pair electrons number of bonding pairs 1 Lewis structures with lower formal charges on the atoms are more plausible 0 formal charge on all atoms is the best 2 If negative formal charge is present it should be assigned to the most electronegative atom Examples of Formal Charge O Resonance is a phenomenon in which bonding electrons are localized all equally good Lewis dot structures are drawn and connected by double headed arrows to indicate that the actual bonding is an average of the bonding in the individual Lewis structures Examples of Resonance
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