Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
___________________________________ Slide 1 ___________________________________ ___________________________________ Chapter 4 Chemical Foundations: Elements, Atoms, and Ions ___________________________________ ___________________________________ ___________________________________ ___________________________________ Slide Chapter 4 2 Table of Contents 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 ___________________________________ ___________________________________ The Elements Symbols for the Elements Dalton’s Atomic Theory Formulas of Compounds The Structure of the Atom Introduction to the Modern Concept of Atomic Structure Isotopes Introduction to the Periodic Table Natural States of the Elements Ions Compounds That Contain Ions ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Copyright © Cengage Learning. All rights reserved Slide Section 4.5 3 The Structure of the Atom 2 ___________________________________ ___________________________________ • • • Substances that cannot be broken down by simple chemical means 115 known: 88 found in nature, others are man made. Just as you had to learn the 26 letters of the alphabet before you learned to read and write, you need to learn the names and symbols of the chemical elements before you can read and write chemistry. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 3 Slide Section 4.5 4 The Structure of the Atom ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 4 ___________________________________ Slide Section 4.5 5 The Structure of the Atom ___________________________________ How the Term Element is Used • • • • Could mean a single atom of that element (Ar or H). Could mean molecules of an element (H2), which is hydrogen found in its natural state. Could mean atoms of elements are present in some form (sodium found in the human body). Look at each particular case to determine its proper use. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 5 ___________________________________ Slide Section 4.2 6 Symbols for the Elements ___________________________________ • • • Each element has a unique one- or two-letter symbol. First letter is always capitalized and the second is not. The symbol usually consists of the first one or two letters of the element’s name. • Examples: Oxygen Krypton ___________________________________ ___________________________________ O Kr ___________________________________ Sometimes the symbol is taken from the element’s original Latin or Greek name. ___________________________________ Examples: Gold Au aurum Lead Pb plumbum ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 6 Slide Section 4.2 7 Symbols for the Elements ___________________________________ ___________________________________ Names and Symbols of the Most Common Elements ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.3 8 Dalton’s Atomic Theory 7 ___________________________________ ___________________________________ 1. Most natural materials are mixtures of pure substances. 2. Pure substances are either elements or combinations of elements called compounds. 3. A given compound always contains the same proportions (by mass) of the elements. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.3 9 Dalton’s Atomic Theory 8 ___________________________________ ___________________________________ Law of Constant Composition • A given compound always has the same composition, regardless of where it comes from. ___________________________________ ___________________________________ Water always contains 8 g of oxygen for every 1 g of hydrogen. Carbon dioxide always contains 2.7 g of oxygen for every 1 g of carbon. ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 9 Slide Section 4.3 10 Dalton’s Atomic Theory ___________________________________ ___________________________________ Dalton’s Atomic Theory (1808) 1. Elements are made of tiny particles called atoms. 2. All atoms of a given element are identical. 3. The atoms of a given element are different from those of any other element. 4. Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers and types of atoms. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.3 11 Dalton’s Atomic Theory 10 ___________________________________ ___________________________________ Dalton’s Atomic Theory (continued) 5. Atoms are indivisible in chemical processes. Atoms are not created or destroyed in chemical reactions. A chemical reaction simply changes the way the atoms are grouped together. ___________________________________ ___________________________________ ___________________________________ ONLY NUCLEAR REACTIONS CAN TRANSFORM ONE KIND OF ELEMENT TO ANOTHER 4 2 2 He ( particle ) 49 B 12 6C ___________________________________ 01n ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.3 12 Dalton’s Atomic Theory 11 ___________________________________ ___________________________________ Concept Check ___________________________________ Which of the following statements regarding Dalton’s atomic theory are still believed to be true? ___________________________________ ___________________________________ I. Elements are made of tiny particles called atoms. II. All atoms of a given element are identical. III. A given compound always has the same relative numbers and types of atoms. IV. Atoms are indestructible. ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 12 ___________________________________ Slide Section 4.4 13 Formulas of Compounds ___________________________________ Chemical Formulas Describe Compounds • • ___________________________________ Compound – distinct substance that is composed of the atoms of two or more elements and always contains exactly the same relative masses of those elements. ___________________________________ ___________________________________ Chemical Formulas – expresses the types of atoms and the number of each type in each unit (molecule) of a given compound. ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 13 ___________________________________ Slide Section 4.4 14 Formulas of Compounds ___________________________________ Rules for Writing Formulas 1. Each atom present is represented by its element symbol. 2. The number of each type of atom is indicated by a subscript written to the right of the element symbol. 3. When only one atom of a given type is present, the subscript 1 is not written. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 14 ___________________________________ Slide Section 4.4 15 Formulas of Compounds ___________________________________ Exercise ___________________________________ The pesticide known as DDT paralyzes insects by binding to their nerve cells, leading to uncontrolled firing of the nerves. Before most uses of DDT were banned in the U.S., many insects had developed a resistance to it. Write out the formula for DDT. It contains 14 carbon atoms, 9 hydrogen atoms, and 5 atoms of chlorine. ___________________________________ ___________________________________ ___________________________________ C14H9Cl5 ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 15 Slide Section 4.5 16 The Structure of the Atom ___________________________________ ___________________________________ J. J. Thomson (1898—1903) • • Postulated the existence of electrons using cathode-ray tubes. The atom must also contain positive particles that balance exactly the negative charge carried by particles that we now call electrons. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.5 17 The Structure of the Atom 16 ___________________________________ ___________________________________ Cathode-Ray Tube ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ J.J. Thomson, measured mass/charge of Copyright © Cengage Learning. All rights reserved Slide Section 4.5 18 The Structure of the Atom e- Return to TOC 17 ___________________________________ ___________________________________ William Thomson (Plum Pudding Model) • Reasoned that the atom might be thought of as a uniform “pudding” of positive charge with enough negative electrons scattered within to counterbalance that positive charge. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 18 Slide Section 4.5 19 The Structure of the Atom ___________________________________ ___________________________________ Ernest Rutherford (1911) • • • • ___________________________________ Explained the nuclear atom. Atom has a dense center of positive charge called the nucleus. Electrons travel around the nucleus at a relatively large distance. A proton has the same magnitude of charge as the electron, but its charge is positive. ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.5 20 The Structure of the Atom 19 ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Rutherford’s alpha particle scattering experiment. 5.5 Copyright © Cengage Learning. All rights reserved Return to TOC 20 Slide Section 4.5 ___________________________________ 21 The Structure of the Atom Rutherford’s alpha particle scattering experiment. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Deflection and scattering of alpha particles by positive gold nuclei. Return to TOC Copyright © Cengage Learning. All rights reserved 21 Slide Section 4.5 ___________________________________ 22 The Structure of the Atom ___________________________________ Rutherford and Chadwick (1932) • Most nuclei also contain a neutral particle called the neutron. • A neutron is slightly more massive than a proton but has no charge. ___________________________________ ___________________________________ ___________________________________ 4 2 49 B 12 6C 01n Energy α particle is a helium nucleus: ___________________________________ 4 2 He 2 ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.5 23 The Structure of the Atom 22 ___________________________________ ___________________________________ • We know atoms are composed of three main pieces - protons, neutrons and electrons • The nucleus contains protons and neutrons • The nucleus is only about 10-13 cm in diameter • The electrons move outside the nucleus with an average distance of about 10-8 cm – therefore the radius of the atom is about 100,000 times larger than the radius of the nucleus ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 23 ___________________________________ Slide Section 4.6 24 Introduction to the Modern Concept of Atomic Structure ___________________________________ The atom contains: • • • Electrons – found outside the nucleus; negatively charged Protons – found in the nucleus; positive charge equal in magnitude to the electron’s negative charge Neutrons – found in the nucleus; no charge; virtually same mass as a proton ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 24 Slide Section 4.6 25 Introduction to the Modern Concept of Atomic Structure • ___________________________________ ___________________________________ The nucleus is: Small compared with the overall size of the atom. Extremely dense; accounts for almost all of the atom’s mass. ___________________________________ ___________________________________ atomic radius ~ 100 pm = 1 x 10-10 m nuclear radius ~ 5 x 10-3 pm = 5 x 10-15 m ___________________________________ ___________________________________ “If the atom is the Houston Astrodome, then the nucleus is a marble on the 50-yard line.” ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 25 ___________________________________ Slide Section 4.6 26 Introduction to the Modern Concept of Atomic Structure ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 26 ___________________________________ Slide Section 4.6 27 Introduction to the Modern Concept of Atomic Structure ___________________________________ Why do different atoms have different chemical properties? • • • ___________________________________ The chemistry of an atom arises from its electrons. Electrons are the parts of atoms that “intermingle” when atoms combine to form molecules. It is the number of electrons that really determines chemical behavior. ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 27 Slide Section 4.7 28 Isotopes ___________________________________ ___________________________________ Isotopes • • • Atoms with the same number of protons but different numbers of neutrons. Show almost identical chemical properties; chemistry of atom is due to its electrons. In nature most elements contain mixtures of isotopes. Mass Number A ZX Atomic Number 1 1H 2 1H (D) 3 1H (T) ___________________________________ ___________________________________ ___________________________________ ___________________________________ Element Symbol 235 92 U 238 92 ___________________________________ U Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.7 29 Isotopes 28 ___________________________________ ___________________________________ Two Isotopes of Sodium A – Z = n (number of neutrons) ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.7 30 Isotopes 29 ___________________________________ ___________________________________ Isotopes A Z ___________________________________ X ___________________________________ • • • X = the symbol of the element Z = the atomic number (# of protons) A = the mass number (# of protons and neutrons) ___________________________________ ___________________________________ A – Z = n (number of neutrons) ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 30 Slide Section 4.7 31 Isotopes ___________________________________ ___________________________________ Isotopes – An Example 14 6 • • • 12 6 C C = the symbol for carbon 6 = the atomic number (6 protons) 14 = the mass number (6 protons and 8 neutrons) ___________________________________ C • C = the symbol for carbon • 6 = the atomic number (6 protons) • 12 = the mass number (6 protons and 6 neutrons) ___________________________________ ___________________________________ ___________________________________ A – Z = n (number of neutrons) ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.7 32 Isotopes 31 ___________________________________ ___________________________________ Exercise ___________________________________ A certain isotope X contains 23 protons and 28 neutrons. • What is the mass number of this isotope? • Identify the element. ___________________________________ ___________________________________ ___________________________________ Mass Number = 51 Vanadium ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.8 33 Introduction to Periodic Table 32 ___________________________________ ___________________________________ The Periodic Table • The periodic table shows all of the known elements in order of increasing atomic number. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 33 Slide Section 4.8 34 Introduction to Periodic Table ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 34 Slide Section 4.8 35 Introduction to Periodic Table ___________________________________ ___________________________________ • order elements by atomic mass • saw a repeating pattern of properties • Periodic Law – When the elements are arranged in order of increasing relative mass, certain sets of properties recur periodically • used pattern to predict properties of undiscovered elements • where atomic mass order did not fit other properties, he re-ordered by other properties – Te & I ___________________________________ ___________________________________ ___________________________________ ___________________________________ Mendeleev ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.8 36 Introduction to Periodic Table 35 ___________________________________ ___________________________________ Periodic Pattern ___________________________________ nm H2O a/b H 1 ___________________________________ H2 m Li2O m/nm BeO nm B2O3 nm CO2 nm N2O5 nm O2 nm OF2 Li b Be a/b B a C a N a O F 7 LiH 9 BeH2 11 ( BH3)n 12 CH4 14 NH3 16 H2O 19 HF ___________________________________ ___________________________________ m Na2O m MgO m Al2O3 nm/m SiO2nm P4O10nm SO3 nm Cl2O7 Na b Mg b Al a/b Si a P a S a Cl a 23 NaH24 MgH2 27 (AlH3) 28 SiH4 31 PH3 32 H2S 35.5 HCl ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 36 Slide Section 4.8 37 Introduction to Periodic Table ___________________________________ ___________________________________ Mendeleev's Predictions for Ekasilicon (Germanium) Property Atomic Mass Color Silicon’s Props 28 Tin’s Props 118 Grey Grey 5.5 GreyWhite 5.4 Resists Both Resists Both Eks1O2 GeO2 Density 2.32 White metal 7.28 Reaction w/ Acid & Base Resists Acid, Reacts Base SiO2 Reacts Acid, Resists Base SnO2 Oxide Predicted Measured Value Value 72 72.6 ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.8 38 Introduction to Periodic Table 37 ___________________________________ ___________________________________ The Periodic Table • • • Metals vs. Nonmetals Groups or Families – elements in the same vertical columns; have similar chemical properties Periods – horizontal rows of elements ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.8 39 Introduction to Periodic Table 38 ___________________________________ ___________________________________ The Periodic Table ___________________________________ ___________________________________ ___________________________________ • • • ___________________________________ Most elements are metals and occur on the left side. The nonmetals appear on the right side. Metalloids are elements that have some metallic and some nonmetallic properties. ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 39 ___________________________________ Slide Section 4.8 40 Introduction to Periodic Table ___________________________________ = Alkali Metals = Halogens = Alkali Earth Metals = Lanthanides = Noble Gases = Actinides ___________________________________ ___________________________________ = Transition Metals ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.9 4.8 41 Natural States the Elements Introduction toof Periodic Table 40 ___________________________________ ___________________________________ Physical Properties of Metals ___________________________________ 1. Efficient conduction of heat and electricity 2. Malleability (they can be hammered into thin sheets) 3. Ductility (they can be pulled into wires) 4. A lustrous (shiny) appearance 5. High densities ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide 42 41 ___________________________________ Section 4.9 4.8 Natural StatestoofPeriodic the Elements Introduction Table ___________________________________ • • Most elements are very reactive. Elements are not generally found in uncombined form. Exceptions are: • Noble metals – gold, platinum and silver • Noble gases – Group 8 ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 42 Slide 43 ___________________________________ Section 4.9 4.8 Natural StatestoofPeriodic the Elements Introduction Table ___________________________________ Diatomic Molecules ___________________________________ ___________________________________ ___________________________________ • ___________________________________ Nitrogen gas contains N2 molecules. • Oxygen gas contains O2 molecules. Copyright © Cengage Learning. All rights reserved Slide 44 ___________________________________ Return to TOC 43 ___________________________________ Section 4.9 4.8 Natural StatestoofPeriodic the Elements Introduction Table ___________________________________ Molecular Elements ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide 45 44 ___________________________________ Section 4.9 4.8 Natural Natural States States oftoof the the Elements Elements Introduction Periodic Table ___________________________________ Allotropes • Different forms of a given element. • Example: – Solid carbon occurs in three forms. • Diamond • Graphite • Buckminsterfullerene ___________________________________ ___________________________________ ___________________________________ ___________________________________ Carbon Allotropes ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 45 Slide Section 4.10 4.8 46 Introduction to Periodic Table Ions • ___________________________________ ___________________________________ Atoms can form ions by gaining or losing electrons. – Metals tend to lose one or more electrons to form positive ions called cations. ___________________________________ ___________________________________ ___________________________________ ___________________________________ – Cations are generally named by using the name of the parent atom. Copyright © Cengage Learning. All rights reserved ___________________________________ Return to TOC 46 ___________________________________ Slide Section 4.10 4.8 47 Introduction to Periodic Table Ions ___________________________________ • Nonmetals tend to gain one or more electrons to form negative ions called anions. ___________________________________ ___________________________________ ___________________________________ ___________________________________ • Anions are named by using the root of the atom name followed by the suffix –ide. ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 47 ___________________________________ Slide Section 4.10 4.8 48 Introduction to Periodic Table Ions ___________________________________ Ion Charges and the Periodic Table The ion that a particular atom will form can be predicted from the periodic table. ___________________________________ Group or Family Charge ___________________________________ Alkali Metals (1A) 1+ ___________________________________ Alkaline Earth Metals (2A) 2+ Halogens (7A) 1– Noble Gases (8A) 0 ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 48 Slide Section 4.8 4.10 49 Introduction to Periodic Table Ions ___________________________________ ___________________________________ Ion Charges and the Periodic Table ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 49 ___________________________________ Slide Section 4.8 4.10 50 Introduction to Periodic Table Ions ___________________________________ Exercise ___________________________________ An ion with a 3+ charge contains 23 electrons. Which ion is it? – – – – a) b) c) d) Fe3+ V3+ Ca3+ Sc3+ ___________________________________ +ve charge ≡ electrons are lost -ve charge ≡ electrons are gained ___________________________________ # of e- = Z – positive charge or # of e = Z + negative charge ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 50 ___________________________________ Slide Section 4.8 4.10 51 Introduction to Periodic Table Ions A – Z = n (number of neutrons) ___________________________________ A certain ion X1+ contains 54 electrons and 78 neutrons. A 0 Z X ___________________________________ What is the mass number of this ion? Z = # of e- + positive charge or Z = # of e- - negative charge Exercise 133 ___________________________________ ___________________________________ ___________________________________ +ve charge ≡ electrons are lost -ve charge ≡ electrons are gained ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 51 Slide Section 4.11 4.8 52 Introduction That Compounds to Periodic Contain Table Ions ___________________________________ ___________________________________ • • Ions combine to form ionic compounds. Properties of ionic compounds ___________________________________ High melting points Conduct electricity ___________________________________ • • ___________________________________ If melted If dissolved in water ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.11 4.8 53 Introduction That Compounds to Periodic Contain Table Ions 52 ___________________________________ ___________________________________ • • Ionic compounds are electrically neutral. The charges on the anions and cations in the compound must sum to zero. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide Section 4.11 4.8 54 Introduction That Compounds to Periodic Contain Table Ions 53 ___________________________________ ___________________________________ Formulas for Ionic Compounds • • Write the cation element symbol followed by the anion element symbol. The number of cations and anions must be correct for their charges to sum to zero. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 54 ___________________________________ Slide Section 4.11 4.8 55 Introduction to Compounds That Periodic Contain Table Ions ___________________________________ Concept Check ___________________________________ A compound contains an unknown ion X and has the formula XCl2. Ion X contains 20 electrons. What is the identity of X? a) b) c) d) ___________________________________ ___________________________________ Ti2+ Sc+ Ca2+ Cr2+ Z = # of e- + positive charge or Z = # of e - negative charge ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 55 ___________________________________ Slide Section 4.11 4.8 56 Introduction to Compounds That Periodic Contain Table Ions ___________________________________ Concept Check ___________________________________ A member of the alkaline earth metal family whose most stable ion contains 36 electrons forms a compound with bromine. What is the correct formula for this compound? a) b) c) d) CaBr2 KrBr RbBr SrBr2 • • ___________________________________ ___________________________________ Ionic compounds are electrically neutral. ___________________________________ The charges on the anions and cations in the compound must sum to zero. ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved Slide 57 56 ___________________________________ Section 4.8 Chapter 4 Homework Introduction to Periodic Table ___________________________________ Homework ___________________________________ • Reading assignment – Pages 74 through 105 ___________________________________ • Homework Problems – Questions and problems 3, 5, 9, 13, 19, 25, 27, 31, 33, 35, 37, 39, 42, 45, 47, 49, 51, 53, 57, 59, 61, 63, 67, 69, 71, 73, 75, 77, 81. • Due on ___________________________________ ___________________________________ ___________________________________ Return to TOC Copyright © Cengage Learning. All rights reserved 57