IonicCompoundStructureAndProperties

Ionic Compounds: 

Ionic Compounds Structure and Properties Students will be able to diagram the formation of a binary ionic compound from the electron configurations of the elements that make it up. They will be able to relate the properties of ionic compounds to their ionic structure.

Compound Formation: 

Compound Formation Ions are formed from atoms so that their electron configuration conforms with a noble gas Thus when Lithium reacts with a chlorine atom Li 1s 2 2s 1 + Cl [Ne] 3s 2 3p 5 Lithium loses its 2s electron to the chlorine atom. The electron completely fills the 2p orbitals of chlorine.

Compound Formation: 

Compound Formation Ions are formed from atoms so that their electron configuration conforms with a noble gas Thus when Lithium reacts with a chlorine atom Li 1s 2 2s 1 + Cl [Ne] 3s 2 3p 5 Lithium loses its 2s electron to the chlorine atom. The electron completely fills the 2p orbitals of chlorine.

Compound Formation: 

Compound Formation Ions are formed from atoms so that their electron configuration conforms with a noble gas Thus when Lithium reacts with a chlorine atom Li 1s 2 2s 0 + Cl [Ne] 3s 2 3p 6 Lithium loses its 2s electron to the chlorine atom. The electron completely fills the 3p orbitals. The outer lithium orbital is empty. + -

Compound Formation: 

Compound Formation Another way to look at the lithium-chloride formation Using the electron-box diagrams Li 1s 2s Cl [Ne] 3s 3p As they react, the Li loses its 2s electron and looks like He, and the Cl gains the electron as a 3p electron and looks like Ar

Compound Formation: 

Compound Formation Another way to look at the lithium-chloride formation Using the electron-box diagrams Li 1s 2s Cl [Ne] 3s 3p As they react, the Li loses its 2s electron and looks like He, and the Cl gains the electron as a 3p electron and looks like Ar

Compound Formation: 

Compound Formation Another way to look at the lithium-chloride formation Using the electron-box diagrams Li 1s 2s Cl [Ne] 3s 3p + - As they react, the Li loses its 2s electron and looks like He, and the Cl gains the electron as a 3p electron and looks like Ar

Compound Formation: 

Compound Formation A third way to look at the lithium-chloride formation Using Lewis “dot” diagrams Remember-ONLY show valence electrons Li ⋅ Cl : : As before, the Li loses an outer- orbital electron and the Cl picks it up, making an octet : ·

Compound Formation: 

Compound Formation A third way to look at the lithium-chloride formation Using Lewis “dot” diagrams Remember-ONLY show valence electrons Li Cl : : : : : : As before, the Li loses an outer- orbital electron and the Cl picks it up, making an octet + -

Practice: 

Practice Show the formation of sodium fluoride in all three ways: electron configuration, boxes and Lewis diagram

Practice: 

Practice Show the formation of sodium fluoride in all three ways: electron configuration, boxes and Lewis diagram Na 1s 2 2s 2 2p 6 3s 1 + F 1s 2 2s 2 2p 5 Sodium loses its 3s electron to the fluorine atom. The electron completely fills the 2p orbitals.

Practice: 

Practice Show the formation of sodium fluoride in all three ways: electron configuration, boxes and Lewis diagram Na 1s 2 2s 2 2p 6 3s 0 + F 1s 2 2s 2 2p 6 The Sodium atom becomes the sodium ion, and the fluorine is now the fluoride anion, with a filled outer shell set of orbitals.

Practice: 

Practice Show the formation of sodium fluoride in all three ways: electron configuration, boxes and Lewis diagram Na 3s [Ne] F [He] 2s 2p As they react, the Na loses its 3s electron and looks like Ne, and the F gains the electron as a 2p electron and looks like Ne

Practice: 

Practice Show the formation of sodium fluoride in all three ways: electron configuration, boxes and Lewis diagram Na 3s [Ne] F [He] 2s 2p + - As they react, the Na loses its 3s electron and looks like Ne, and the F gains the electron as a 2p electron and looks like Ne

Lewis Diagram: 

Lewis Diagram As you can see, if you have the valence electrons correct, this is the easiest method Before: Na ⋅ : F ⋅ : : After: Na : F : : : + -

Sample Problem 15-1: 

Sample Problem 15-1 Use Lewis structures to predict the formulas of the ionic compounds formed from Potassium and oxygen Magnesium and nitrogen

Sample Problem 15-1: 

Sample Problem 15-1 Use Lewis structures to predict the formulas of the ionic compounds formed from Potassium and oxygen Magnesium and nitrogen K ⋅ : O ⋅ : ⋅ 2 potassiums are needed for each oxygen Mg : : N ⋅ ⋅ ⋅ 3 magnesiums are needed for each 2 nitrogens

More Practice: 

More Practice Using Lewis structures, determine the chemical formulas of ionic compounds formed from Potassium and iodine Aluminum and oxygen K + : I - : Al 3+ Al 3+ 2 - : : : : O 2 - : : : : O 2 - : : : : O Of course, these are the same results given by the cris-cross rule : :

Some Binary Minerals: 

Some Binary Minerals Hematite Fe 2 O 3 Rutile TiO 2 Pyrite FeS 2 Cinnabar HgS

Ionic Compound Properties: 

Ionic Compound Properties Since the elements have a higher energy than the ions. . . The compounds are very stable Generally requires electrolysis to break up They have high melting points (electrostatic attraction bonds + to - ) Most binary ionic compounds are not very soluble in water for the same reason Exceptions: alkali salts

Seeing Inside Crystals: 

Seeing Inside Crystals Using X-ray diffraction crystallography The apparatus (@ U. of Arizona) X-ray diffraction image of powdered NaCl

Metallic Bonding: 

Metallic Bonding Metals have electrons loosely held in s or d orbitals Metallic bonds consist of the attraction of those loosely held electrons for the positive ion core of the metal They are so movable that metals are easy to “mash” (malleable) and bend Ionic crystals, however, consist of rigidly held charges, so they tend to crack or crush into powder when you try to mash or bend them

Metallic Structures: 

Metallic Structures Body-centered cubic Sodium, potassium, iron, chromium

Metallic Structures: 

Metallic Structures Body-centered cubic Sodium, potassium, iron, chromium Face-centered cubic Copper, silver, gold, aluminum, lead

Metallic Structures: 

Metallic Structures Body-centered cubic Sodium, potassium, iron, chromium Face-centered cubic Copper, silver, gold, aluminum, lead Hexagonal close-packed Magnesium, zinc, cadmium

Metallic Alloys: 

Metallic Alloys Some important ones Sterling silver: 92.5% Ag, 7.5% Cu Tougher than finesilver Brass: copper and zinc Bronze: copper and tin Steel Stainless: Fe, Cr, small amounts of C & Ni Surgical: Fe, Cr, Ni, small amount of Mo “Holds an edge very well”