today is thursday, october 16 th, 2014 pre-class: when we were naming things like co 2 and hno 3 and...
TRANSCRIPT
Today is Thursday,October 16th, 2014
Pre-Class:When we were naming things like CO2 and HNO3 and SrF2, what were all the atoms in
those compounds actually doing?
Also, take a worksheet and a paper towel.
Stuff You Need:Paper TowelWorksheet
In This Lesson:Ionic and Metallic
Bonding(Lesson 3 of 4)
Today’s Agenda
• Ionic and Metallic Bonds– How ions and metals come together…– …and stay together. Awww…
• Australian Bonding Videos– Koalas not included.
• Where is this in my book?– P. 194 and following…
By the end of this lesson…
• You should be able to describe the nature of an ionic or metallic bond.
Introductory Video
• TED: George Zaidan and Charles Morton – How Atoms Bond
Bonding Overview
• Like with Periodic Table Trends, I have a handy way of organizing this information.– Bonding Overview
The Types of Bonding
• There are three types of bonds out there:• Ionic Bonds– Metal/Nonmetal – Electrons are transferred from one
atom to another.• Metallic Bonds– Metal/Metal – A mixture of metals with delocalized
electrons that flow through all atoms’ shells.• Covalent/Molecular Bonds– Nonmetal/Nonmetal (or metalloid) – Electrons are
shared/fought over between atoms.
Ionic Bonding Video
• Australian!
Ionic Bonds
• Cations and anions are formed.– Metals lose electrons to achieve the octet.– Nonmetals gain electrons to achieve the octet.
• Opposite charges attract one another, forming the bond.
• The resulting compound is neutral.
Ionic Compounds
• Crystalline solids at room temperature– Think table salt.
• High melting points– Takes a lot of heat/energy to melt them.
• Conduct electricity when melted or dissolved– Electric eels in seawater.
• Finish your Bonding Overview sheets for Ionic Bonding. Questions?
Dissociation
• In water, ionic compounds sometimes break up into the ions of which they’re composed.– This is a process called dissociation.
Dissociation
CaCl
Cl
Ca2+Cl-
Cl-
Bound ions in… …component ions out.
Metallic Bonding Video
• Aluminium!
Metallic Bonds
• In metallic bonds, all the cations are packed closely together.
• The valence electrons, rather than hanging out near their atoms’ nuclei, exist in a sea of delocalized electrons.– They float around everywhere and act as a glue, like mortar
around bricks in a building.• There is still an attraction between the free floating
electrons (-) and metal cations (+).
Metallic Compounds
• Good conductors of electricity– Think copper wiring.
• Ductile and malleable– Think copper wiring.
• Melting points vary• Insoluble in water
– Cause, well, metals just don’t dissolve.• Alloys
– Mixtures of two or more metals that have superior properties to their components.• Brass, bronze, steel are alloys.
• Finish your Bonding Overview sheets for Metallic Bonding. Questions?
Ionic Lewis Dot Structures
• In order to understand ionic compounds, it helps to be able to draw Lewis Dot Structures for ionic compounds.
• Let’s practice using an easy ionic compound – sodium chloride.
Ionic Lewis Dot Structures
• First, find the chemical formula for the compound.– Na likes to form 1+ ions, Cl likes to form 1- ions.– Na+ and Cl- balance together in a formula as NaCl.
• Then, draw the appropriate number of electrons in Lewis Dot form.
• Finally, “transfer” the electrons appropriately.
Na Cl
Ca
Ionic Lewis Dot Structures
• Example: Calcium oxide– CaO
O
Ionic Lewis Dot Structures
• Try this one: Aluminum nitride– AlN
Al N
Ionic Lewis Dot Structures
• Try this one: Magnesium sulfide– MgS
Mg S
Ionic Lewis Dot Structures
• Example: Iron (II) chloride– FeCl2
Fe Cl
Cl
Ionic Lewis Dot Structures
• Try this one: Cobalt (III) fluoride– CoF3
Co F
F
F
Ionic Lewis Dot Structures
• Try this one: Lithium oxide– Li2O
OLi
Li
Ionic Lewis Dot Structures
• Try this one: Silver phosphide– Ag3P
PAg
Ag Ag
Ionic Lewis Dot Structures
• Try this one: Barium nitride– Ba3N2
N BaBaBa
N
Ionic Lewis Dot Structures
• Try this one: Aluminum oxide– Al2O3
OAl
AlO
O
Ionic Lewis Dot Structures
• Try this one: Zinc iodide– ZnI2
Zn I
I
Practice
• Ionic Bonding Worksheet– Pages 1/2
Closure
• Try this one: Gold (III) sulfide– Au2S3