Chem 102 Exam I Study Guide PART II NNNN oooo tttt eeee bbbb oooo oooo kkkk CHEM 102 CCCCrrrreeee aaaatttt eeee dddd TTTT aaaagggg ssss 9 24 2012 3 30 PM CHEM 102 Study Guide UUUU pppp dddd aaaatttt eeee dddd 9 25 2012 12 26 AM Pre Lecture early early morning 9 12 12 and also Lecture 9 12 12 2 7 An Introduction to the Periodic Table Metals tend to form cations ions by LOSING electrons Nonmetals tend to form anions ions by GAINING electrons Elements in the same vertical column in the periodic table form a group family have similar properties have the same number of valence electrons Ex Group Family 8 the Noble Gases Horizontal rows Periods deals with principle quantum number 2 8 Naming Simple Compounds Binary Compounds compounds composed of 2 elements which we classify into various types for easier recognition Binary Ionic Compounds Type I contain a cation METAL and an anion NONMETAL 1 The cation is always named first and the anion is named second 2 The monoatomic cation is just called by its elemental name 3 The monoatomic anion is named by taking the elemental name root and adding the suffix ide Ex Na Cl sodium chloride The metal present forms only a single type of cation Binary Ionic Compounds Type II 1 Way to do it number 1 the charge on the metal cation must be specified through ROMAN NUMERALS and TRANSITION METALS b c the metals are the Transition Metals that form more than one type of charge Ex CuCl Cu and Cl Copper I chloride 2 Way to do it number 2 older literature system that was used for metals that form only two ions The ion with the higher charge ends in ic and the lower charger ends in ous Ex Fe3 FERRIC ION Fe2 FERROUS Ion So FeCl3 ferric chloride and FeCl2 ferrous chloride Elements that form only one cation do not need a Roman numeral s block metals TYPE I Aluminum forms only Al3 Silver found as Ag ion Zinc found as Zn2 Ionic Compounds with Polyatomic Ions Oxyanions anions that contain an atom of a given element and different numbers of oxygen atoms when there are 2 members in a series smaller of Oxygens suffix ite larger of Oxygens suffix ate Ex SO3 2 sulfite and SO4 2 sulfate when more than 2 oxyanions make up a series fewest oxygen atoms prefix hypo less than most oxygen atoms prefix per more than Binary Covalent Compounds Type III Binary Covalent Compounds are formed between two NONMETALS do NOT contain ions 1 The first element in the compound is named first and keeps its full elemental name 2 The second element is named as if it were an anion with the suffix ide 3 Prefixes are used to denote the numbers of atoms present 1 mono 6 hexa 2 di 7 hePTa 3 tri 8 octa 4 tetra 9 nona 5 penta 10 deca 4 The prefix mono is NEVER used for naming the first element Ex CO carbon monoxide NOT monocarbon monoxide Acids Acids a substance that produces hydrogen ions in solution a proton doner it is a molecule in which one or more H ions are attached to an anion the rules for naming acids depend on whether the anion contains oxygen If the name of the anion ends in the suffix ide prefix hydro and suffix ic Ex HCl Hydrochloric Acid E A S Y If the anion contains oxygen the acidic name is formed from the root name of the anion with a suffix of ic or ous 1 If the anion name ends in ate then the suffix ic is added to the root name 2 If the anion has an ite ending then the ite is replaced by ous Pre Lecture 9 16 12 3 1 Counting by Weighing Average Mass total mass of beans number of beans Objects do not need to have identical mases to be counted by weighing For purposes of counting the objects behave as though they were identical as though they each actually had the average mass We determine the number of atoms in a given sample by finding its mass However we must know the average mass of the atoms 3 2 Atomic Mass 12C pronounced Carbon 12 standard 12C is assigned a mass of exactly 12 atomic mass units amu and the masses of all the other atoms are given alloted relative according to this standard Use of mass spectrometer 1 Atoms MCs passed into a beam of high speed electrons 2 The electrons knock electrons off the atoms MCs being analyzed this turns them into positive ions cations 3 Applied electric field then accelerates these ions into a magnetic field an interaction between the 2 changes the path of the ion 4 Most massive ions smallest path deflection This causes the ions to separate where they hit the plate accurate relative masses Mass of 13C Mass of 12C 1 0836129 Mass of 13C 1 0836129 12 amu 13 003355 amu Atomic Mass Atomic Weight Most elements occur in nature as mixtures of isotopes thus atomic masses are usually average values EX C 12 01 B c natural carbon is a mixture of isotopes the atomic mass for C average value reflecting the avg of the isotopes composing it How to compute the average atomic mass for C known C 98 89 12C atoms and 1 11 13C 98 89 x 12 amu 1 11 x 13 004 amu 12 01 amu even though natural C doesn t contain a single atom w mass 12 01 for stoichiometric purposes we can consider C to be composed of only one type of atom w a mass of 12 01 Counting by Weighing For natural C w an average mass of 12 01 amu to obtain 1000 atoms would require weighing out 12 010 amu of natural C btw natural C is a mixture of 12C and 13C NO atom of Hydrogen actually has the mass 1 008 The mass spectrometer is useful in determining the isotopic composition of a natural element 3 3 The Mole mole mol to the of C atoms in exactly 12 g of pure 12C 6 022 x 10 23 Avogadro s Number The mole is defined such that a sample of a natural element with a mass equal to the element s atomic mass expressed in grams contains 1 mole of atoms ex 6 022 x 10 23 atoms x 12 amu atom 12 g ex 6 022 x 10 23 amu 1 g 3 4 Molar Mass How can we calculate the mass of 1 mole of Methane What is the mass of 6 022 x 10 23 CH2 molecules mass of 1 mol C 12 01 g mass of 4 mol H 4 x 1 008 g mass 1 mol CH4 16 04 g Molar Mass the mass in grams of 1 mole of the compound AKA Molecular Weight For ionic compounds instead of molecule Formula Unit 7 12 Periodic trends in Atomic Properties Ionization Energy the energy required to remove an electron from a gaseous atom …