Chapter Four Chemical Bonding: The Ionic Bond Model

Chapter 4 | Slide 2 Chemical Bonding: The Ionic Bond Model cont’d Chemical Compounds _________ Compounds –Usually Metal and Nonmetal ions –________ Bonds –Solids, high melting, conducts electricity (molten or in solution) __________ Compounds –Usually between Atoms of same Element or between atoms of nonmetals –__________ Bonds –Gases, liquids, or low melting solids, non-conductor

Chapter 4 | Slide 3 Chemical Bonding: The Ionic Bond Model cont’d What are chemical bonds? Chemical bond: attractive _______ holding two or more atoms together. Ionic bond results from the attraction of ________ and ____________ ions –Usually, a metal forms the ________ ion and a nonmetal forms the _________ ion Covalent bond results from _________ electrons between the atoms. –Usually found between ____________

Chapter 4 | Slide 4 Chemical Bonding: The Ionic Bond Model cont’d Chapter 4 Focus is on Ionic Bonds Bond formed through the ________ of one or more electrons from one atom or group of atoms to another atom or group of atoms Metals tend to give up electrons and form ______ Non-metals tend to accept electrons and form _________ The Ionic Bond is formed by the attraction between the _____ and ____ charges

Chapter 4 | Slide 5 Chemical Bonding: The Ionic Bond Model cont’d Recall Chapter 3 Topic Electron Configurations Electrons residing in outer most energy level are called distinguishing or valence electrons Valence electrons determine chemical properties or how atoms of one particular element interact (give up or gain electrons) with atoms of another element

Chapter 4 | Slide 6 Chemical Bonding: The Ionic Bond Model cont’d Valence Electrons: –Example: Mg: ________________________ –Example: Cl: ____________________________ An easy way to determine how many valence electrons an element has: –The number of valence electrons is _______ to the group number (for elements in the s and p blocks)

Chapter 4 | Slide 7 Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 | Slide 8

Chapter 4 | Slide 9 Chemical Bonding: The Ionic Bond Model cont’d How many valence electrons do the following elements have? –Na –Al –S –Cl

Chapter 4 | Slide 10 Chemical Bonding: The Ionic Bond Model cont’d Lewis Symbol Is the chemical symbol of an element surrounded by dots equal in number to the number of __________ electrons present in atoms of the element Elements in the same group have the same number of ___________ electrons The number of __________ electrons for elements in the same group is the same as the “A” Group number The maximum number of ____________ electrons for any element is eight (H and He exceptions) Eight ____________ electrons is most stable and results in the rule of eight or octet rule to produce a noble gas electron configuration

Chapter 4 | Slide 11 Chemical Bonding: The Ionic Bond Model cont’d →Fig. 4.2 Gilbert Newton Lewis was one of the foremost chemists of the 20 th century. Edgar Fahs Smith Collection, University of Pennsylvania Library

Chapter 4 | Slide 12 Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 | Slide 13 ←Fig. 4.3 Loss of an electron from a sodium atom leaves it with one more proton than electrons, so it has a net electrical charge of +1. Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 | Slide 14 Chemical Bonding: The Ionic Bond Model cont’d Fig. 4.4 a-c (a,b) Two-dimensional cross section and a three-dimensional view of sodium chloride. (c) sodium chloride crystals

Chapter 4 | Slide 15 Focus on Mg and Cl Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 | Slide 16 Chemical Bonding: The Ionic Bond Model cont’d Let’s look at Mg. Its electron configuration is 1s 2 2s 2 2p 6 3s 2. –If it loses ____ electrons to become ________, it will have the electron configuration 1s 2 2s 2 2p 6 ____ Valence Electrons! –If it gains ____ electrons to become ______, it will have the electron configuration 1s 2 2s 2 2p 6 3s 2 3p 6 ___ Valence Electrons! –The question is which is easier? To lose TWO electrons or to gain SIX? Losing two: Therefore, Mg tends to form Mg 2+ ions

Chapter 4 | Slide 17 Chemical Bonding: The Ionic Bond Model cont’d Let’s look at Cl. Its electron configuration is 1s 2 2s 2 2p 6 3s 2 3p 5. –If it loses ____ electrons to become ______, it will have the electron configuration 1s 2 2s 2 2p 6 ___ Valence Electrons! –If it gains _____ electron to become ______, it will have the electron configuration 1s 2 2s 2 2p 6 3s 2 3p 6 ___ Valence Electrons! –The question is which is easier? To lose SEVEN electrons or to gain ONE? Losing ONE: Therefore, Cl tends to form Cl - ions

Chapter 4 | Slide 18 Chemical Bonding: The Ionic Bond Model cont’d So, Mg will form Mg 2+ ions, and Cl will form Cl - ions. Opposite charges attract: Mg Cl -  MgCl 2

Chapter 4 | Slide 19 Chemical Bonding: The Ionic Bond Model cont’d Isoelectronic Species Are atoms or ions that have the ______ number and configuration of electrons. N 3- O 2- F 1- Na 1+ Mg 2+ Al 3+ All are isoelectronic with ______ and all have the electronic configuration 1s 2 2s 2 2p 6

Chapter 4 | Slide 20 Chemical Bonding: The Ionic Bond Model cont’d Formula Units The smallest whole number repeating ratio of ions present in an ionic compound that results in charge neutrality. NaCl MgCl 2 AlCl 3 Na 2 O MgO Al 2 O 3

Chapter 4 | Slide 21 →Fig. 4.5 Cross section of the structure of the ionic solid NaCl. Chemical Bonding: The Ionic Bond Model cont’d E. R. Degginger/Color-Pic

Chapter 4 | Slide 22 Chemical Bonding: The Ionic Bond Model cont’d The number of electrons an atom loses or gains is related to its position on the periodic table.

Chapter 4 | Slide 23 Chemical Bonding: The Ionic Bond Model cont’d Group IA metals Group IIA metals Group IIIA metals Group VIIA nonmetals Group VIA nonmetals Group VA nonmetals

Chapter 4 | Slide 24 Chemical Bonding: The Ionic Bond Model cont’d →Fig. 4.8 Periodic table in which the metallic elements that exhibit a fixed ionic charge are highlighted.

Chapter 4 | Slide 25 Chemical Bonding: The Ionic Bond Model cont’d Writing Formulas for compounds For compounds, a neutral species, the number of electrons lost and gained must be _______. The amount of positive charge must _______ the amount of negative charge. Formulas of ionic compounds –Symbol for the positive ion is always written first –The charges on the ions are _______ shown in the formula –The _____________ in the formula give the combining ratio for the ions

Chapter 4 | Slide 26 Chemical Bonding: The Ionic Bond Model cont’d It may be helpful to initially write in the charges of each ion, then determine the number of + and – ions that would balance out the charges. K 1+ S 2- Al 3+ O 2-

Chapter 4 | Slide 27 Chemical Bonding: The Ionic Bond Model cont’d Naming Ionic Compounds First word of name: –Name of ___________ (first element in formula) –If the metal can form more than one _________, then the charge is indicated in parentheses in the name. Examples: Cu + = copper (I); Cu 2+ = copper (II). Second word of name: –Name of ________ (second element in formula). Write the _____ of the name of the nonmetal ion with the –ide ending

Chapter 4 | Slide 28 Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 | Slide 29 Chemical Bonding: The Ionic Bond Model cont’d What is the name or formula for each of the following? K 3 N AuCl 3 PbS

Chapter 4 | Slide 30 Chromium (III) oxide Iron (II) oxide Magnesium Chloride

Chapter 4 | Slide 31 Chemical Bonding: The Ionic Bond Model cont’d Thus far these have been compounds formed by Metal Cations and Non-metal Anions. An ionic compound in which one element present is a metal and the other element present is a nonmetal is called a “_________ Ionic Compound”

Chapter 4 | Slide 32 Chemical Bonding: The Ionic Bond Model cont’d Monatomic ion –An ion formed from a _______ atom through loss or gain of electrons –Examples: Na +, S 2-, etc. Polyatomic ion –An ion formed from a ______ of atoms (held together by covalent bonds) and as a whole becomes charged through loss or gain of electrons –Can be the positive or the negative ion in an ionic compound

Chapter 4 | Slide 33 Chemical Bonding: The Ionic Bond Model cont’d

Chapter 4 | Slide 34 Chemical Bonding: The Ionic Bond Model cont’d Give the formulas and names of the ionic compounds formed between the following ions: –NH 4 + & PO 4 3- –Na + & NO 3 1- –NH 4 + and O 2-

Chapter 4 | Slide 35 –NH 4 + and PO 4 3- –Li + and CO 3 2- –Mg 2+ and NO 3 1-

Chapter 4 | Slide 36 Chemical Bonding: The Ionic Bond Model cont’d