CHEMICAL BONDS Ionic & Metallic Bonding Chemistry Jacqueline P. Hancock, B.S., M.Ed
EQ1: How do atoms obtain stability? Cornell Set up EQ1: How do atoms obtain stability? Cover page Vocabulary foldable.. ~due 1/09/17
CHEMICAL BONDING Chemical Reactivity THE NATURE OF THE UNIVERSE IS TO GO FROM HIGH ENERGY TO LOW OR FROM CHAOS TO STABILITY ALL ATOMS NEED TO ACHIEVE STABILITY; UNLESS THEY ARE NATURALLY STABLE Atoms will undergo chemical reactions to become stable. ATOMS WILL OBEY THE OCTET RULE OF STABILITY
CHEMICAL BONDS A bond is an attachment among atoms Bonds occur due to Sharing electrons Losing electrons Gaining electrons Bonding depends on chemical properties such as electron configurations
THE EXCEPTIONS ARE H AND He
How many electrons per level? Valence electrons
EQ 1 HOT Questions & Summary Write Higher Order of Thinking Questions 1 level 1 question 2 level 2 questions 1 level 3 question Write Summary of EQ 1. Make sure you answered all of your HOT questions
How do we model valence electrons? How do metals achieve stability? EQ2: How do we model valence electrons? How do metals achieve stability?
How do we find the valence e- Valence e- are usually the only e- used in chemical bonds The group number of representative elements is their valence electron # Electron Dot Structures show valence e- Lewis Structures Electron Dot Diagrams
Dot Diagrams
Practice on Board!! Draw the Lewis Structures in your INB
IONIC BONDING Metals tend to lose electrons to make the outside ring(s) more stable Non Metals tend to gain electrons to complete the outside ring ION-a charged particle: an atom that is either positively or negatively charged
Cation + Anion
Cations Name of the cation is the same as the element Cation formed by loss of e- by metals with 1-3 valence e- positive ion [+] (protons)+(electrons)=charge Properties of element and ion are different Sodium reacts violently with water Sodium ion is un-reactive Most metals will readily form cations. Low ionization energies to the left and bottom
Examples of Cations (Write the cations for group 1 &2) Name of element Cation Cation Name Lithium Li+1 Lithium Ion Sodium Na +1 Sodium Ion
High electron affinities in the upper right hand portion Anions High electron affinities in the upper right hand portion
Add to notes table page 192
Transition elements Ag 1s22s23p63d104s24p64d105s1 e- gained or lost will vary between 2 or 3 Will not give up or take more than 3e- Ions with charges >3 are uncommon They will settle for pseudo noble gas configuration Ag 1s22s23p63d104s24p64d105s1 Two Possibilities Instead it loses Kr or Xe 1 e- to achieve outer Lose 11 e- or gain 7e- level and all other This doesn’t happen!! orbitals filled
Pseudo-Noble Gas Configuration Positive ion produced from loss of all valence electrons from a representative metal will have either: Noble gas configuration(same configuration as a noble gas) ns2np6 or 1s2 for period 2 Pseudo-noble gas electron configuration the outermost shell has the configuration ns2np6nd10 example Zn+2 1s22s22p63s23p63d10
Oxidation numbers How many electrons an atom gained, lost, or shared to become stable. In Ionic compounds this number is the same as the charge of the ion Group # Oxidation # Group 1 +1 Group 2 +2 Group 13 +3 Group 14 +4 Group 15 -3 Group 16 -2 Group 17 -1 Group 18
+2 or +3*
Chemical Formula Chemical Formula NaCl MgCl2 Formula Unit Representing the smallest types and numbers of atoms in a substance NaCl MgCl2 Formula Unit The lowest whole number ration of ions in an ionic compound 1:1 1:2
Which pairs will combine? Why or Why not? (INB-left pg) show your work Cl, Br Li, Cl I, Na O, S Al, O I, K F, Cl
Identify the ions in the compounds-INB left page CaF2 AlBr3 Li2O Al2S3 KCl MgBr2 BaSO4 Li2CO3 Make a table like this Compound Cation(+) Anion(-) K3N K+ N-3
EQ 2 HOT Questions & Summary Write Higher Order of Thinking Questions 3 level 1 question 3 level 2 questions 1 level 3 question Write Summary of EQ 2. Make sure you answered all of your HOT questions
EQ3: How can you describe the arrangement of atoms in a metal
Metallic Bonds and Metallic Properties 7.3 Metallic Bonds and Metallic Properties The valence electrons of metal atoms can be modeled as a sea of electrons. The valence electrons are mobile and can drift freely from one part of the metal to another. Metallic bonds consist of the attraction of the free-floating valence electrons for the positively charged metal ions.
Metallic Bonds and Metallic Properties 7.3 Metallic Bonds and Metallic Properties A force can change the shape of a metal. A force can shatter an ionic crystal. A metal rod can be forced through a narrow opening in a die to produce wire. a) As this occurs, the metal changes shape but remains in one piece. b) If an ionic crystal were forced through the die, it would shatter. Interpreting Diagrams What causes the ionic crystal to break apart?
Metallic Bonds and Metallic Properties 7.3 Metallic Bonds and Metallic Properties A metal rod can be forced through a narrow opening in a die to produce wire. a) As this occurs, the metal changes shape but remains in one piece. b) If an ionic crystal were forced through the die, it would shatter. Interpreting Diagrams What causes the ionic crystal to break apart? Metals are ductile—that is, they can be drawn into wires.
Properties of Ionic Compounds Have coordination numbers( # of ions of opposite charge that surround an ion in a crystal) 4 or 6 coordination # are the most common Most are crystalline solids at room temp High melting points Conduct electric current when melted or dissolved
Crystalline Structure of Metals 7.3 Crystalline Structure of Metals Crystalline Structure of Metals How are metal atoms arranged?
Crystalline Structure of Metals 7.3 These tomatoes have a closed-packed arrangement. Similar arrangements can be found in the crystalline structure of metals. These tomatoes illustrate a pattern called a hexagonal close-packed arrangement.
Crystalline Structure of Metals 7.3 Crystalline Structure of Metals Metal atoms are arranged in very compact and orderly patterns. Metal atoms crystallize in characteristic patterns. a) Chromium atoms have a body-centered cubic arrangement. b) Gold atoms have a face-centered cubic arrangement. c) Zinc atoms have a hexagonal close-packed arrangement. Inferring Which of these arrangements is the most closely packed?
Coordination Numbers Create a table showing the name of the coordination and the number of surrounding atoms.(Left pg) Linear 2 Triangular 3
Explain the importance of alloys EQ3: How can you Explain the importance of alloys
7.3 Alloys Alloys are mixtures composed of two or more elements, at least one of which is a metal. Alloys are important because their properties are often superior to those of their component elements.
7.3 Alloys Alloys Why are alloys important?
7.3 Alloys The most important alloys today are steels. Steels have a wide range of useful properties, such as corrosion resistance, ductility, hardness, and toughness.
7.3 Alloys Bicycle frames are often made of titanium alloys that contain aluminum and vanadium. Bicycle frames are often made of titanium alloys that contain aluminum and vanadium.
EQ 3 HOT Questions & Summary Write Higher Order of Thinking Questions 2 level 1 question 2 level 2 questions 1 level 3 question Write Summary of EQ 3.