CHEM 112 Chapter 3 PART 1
CHEM 112 Chapter 3 PART 1 Chem 112
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This 0 page Class Notes was uploaded by Ale Guzman on Wednesday January 27, 2016. The Class Notes belongs to Chem 112 at University of Illinois at Chicago taught by Dr. Sherwin Montano in Winter 2016. Since its upload, it has received 59 views. For similar materials see General Chemistry in Chemistry at University of Illinois at Chicago.
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Date Created: 01/27/16
SPRING 2016 CHEM 112 MONTANO Predictable Charges 0 The nonmetals with the exception of the noble gasses in the last column and the the metals in the rst two groups columns of the periodic table have predictable charges 0 For the rst two groups the group number will be equal to the positive charge it has 0 Ca has a charge of 2 as an ion since it is in the 2nCI group 0 Na has a charge of 1 as an ion since it is in the 1st group 0 The nonmetals negative charge will be equal to how many columns it is away from the noble gasses 0 Br has a charge of 1 as an ion since it is 1 column away from the noble gasses o N has a charge of 3 as an ion since it is 3 columns away from the noble gasses Aluminum usually has a charge of 3 Chemical bonds 2 types Covalent o Mainly between nonmetals o Involves the sharing of electrons every atoms valence shell must be consisted of 8 electrons with the exception of hydrogen and helium who need 2 in order for it to be stable The bigger circles represent atoms and the blue dots represent electrons The fact that these atoms need to share electrons is what Ionic o Occurs between metals and nonmetals o Involves the transfer of electron from one ion cation metal to the other anion nonmetal meaning one atom or molecule becomes positively charged the one giving up the electron and the other becomes negatively charged the one receiving the electron Ionic bonds differ from covalent bonds because the binding force that keeps the molecule together comes from the electrostatic force of the positive cation and the negative anion being Chemical formulas 0 Empirical formula 0 Gives relative number of atoms of each element in the compound in the lowest ratio possible of whole numbers CH2 CCI4 SPRING 2016 CHEM 112 MONTANO 0 Molecular formula 0 Gives the actual amount of each element present in a speci c molecule 39 C4H8 C2C8 o The molecular and empirical formula for the same group of compounds will always have the same ratio sometimes they will be the same formula such as methane CH4 its molecular formula has the smallest ratio of whole numbers possible 0 Structural formula 0 Uses lines in between the atoms to show covalent bonds C02 in structural formula will be written as OCO H202 in structural formula will be written as HOOH 0 Every atom is accounted for and bonds are shown 0 Molecular models 0 Shows the structural formula in a 3dimensional way showing how the structure of the atom will look in real life by positioning the atoms in geometrical positions 0 There are two types of molecular models Ball and Stick molecular model 0 The balls represent the atoms in the molecular formula and are usually color coded to their corresponding atom o The sticks represent the bonds between the atom Space lling molecular model 0 Like the ball and stick model except there is nothing to indicate covalent bonds and atoms are just squished together in this model Compounds 0 Molecular 0 Usually composed of two or more covalently bonded nonmetals o Nonmetals are located on the top right most side of the periodic table plus hydrogen 0 Composed of cations usually a metal and anions usually one or more nonmetals bound together by ionic bonds 0 Usually ionic compounds don t exist in one molecule they usually exist only in a collection of the same ionic compound 0 The overall charge of the compound MUST be neutral meaning the sum of the charge of the cation must equal the negative sum of the anion o EX What is the formula for Magnesium bromide I If you look at the periodic table magnesium is in the 2nCI group meaning it has a charge of 2 Bromine is in the 7th group meaning it has a charge of 1 If we were to make a SPRING 2016 CHEM 112 MONTANO compound with both magnesium and bromine we need the overall charge to be neutral meaning we need two of bromine to make a negative charge of 2 and one of magnesium to make a positive charge of 2 This makes the molecular formula MgBrz Polyatomic Ions 0 Sometimes ionic compounds contain more than one atom and a lot of the time this is a polyatomic ion 0 It is a group of covalently bonded meaning the ion itself is molecular atoms with an overall charge of positive or negative usually negative since more polyatomic ions are made with nonmetals o Oxyanions are polyatomic ions that contain oxygen and another element and there are usually a series of multiple simiar ions and they are named for how many oxygens they have 0 If there are two ions in the series the one with more oxygen atoms ends in ate and the one with less ends in ite N0339 is named nitrate N0239 is named nitrite o If there are more than two these two suf xes are used but pre xes are also added to help distinguish The pre x hypo means quotless thanquot and the pre x per means quotmore thanquot CIO439 is named perchlorate CIO339 is named chlorate CIOz39 is named chlorite CIO39 is named hypochorite Naming Ionic Compounds amp Formula 0 Naming Binary onic Compounds WITH REPRESENTATIVE METALS 0 Name the cation metal rst name does not change 0 The anion nonmetal is named second take the base of the name and add ide KCI will be potassium chloride CaO will be calcium oxide Naming Binary onic Compounds WITH TRANSITION METALS 0 Tip for nding charges Transition metals can change their charge unlike the metals in groups 1 amp 2 called the representative elements so their charge cannot be predicted like the representative elements You can nd the charge of the transition metal by guring out the charge of the anion that makes up the other half of the ionic compound 0 If you look at Fe203 Oxygen will always have a charge of 2 meaning the anion will have a charge of 6 since there is 3 oxygen atoms If you divide 6 by SPRING 2016 CHEM 112 MONTANO 2 since there are 2 iron atoms you get a charge of 3 for iron the cation 0 The transition metal will be named rst followed by its charge in parenthesis use roman numerals for charge 0 The anion will be named last with its base name followed by ide Fe203wi be iron Ill oxide CrBr3will be chromium Ill bromide Naming onic Compounds Containing Polyatomic ons o The naming of ionic compounds with polyatomic ions is essentially the same as other ionic compounds except the name for the polyatomic ion is used in place of the names of the molecule NaNOz is named sodium nitrite N02 is the polyatomic ion
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