Bell Ringer10-27-09

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Bell Ringer 10-27-09

1. Covalent bonds are usually between _______.
2. Ionic bonds are usually between _______.
3. Ionic bonds are the _______ of electrons.
4. Covalent bonds are the _______ of electrons.
5. What are the two kinds of covalent bonds?
6. What type of covalent bonds involves unequal
   sharing of e-?

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ALCOS Objectives

• 2 Describe the structure of atoms.
• 5 Differentiate between ionic and covalent
  bonds.

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Chapter 5 Section 4

• Metallic Bonding

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Why use Metals instead of Nonmetals?
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Physical Characteristics of metals

• Luster- Shiny and Reflective
• Good conductors of heat or electricity
• Most are solids at room temperature
• Ductile
• Malleable

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Chemical properties

• Reactivity
• The reactivity of metals tends to decrease as you
  move from left to right across the periodic table.

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Alloys

• An alloy is a mixture made of 2 or more elements
  that has the properties of a metal.
• In every alloy at least one of the elements is a
  metal.
• Alloys are generally stronger and less likely to
  react with air or water than pure metals are.

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Examples

• Jewelry
• Not necessarily pure gold
• Usually an alloy of gold with a harder metal
• Tools
• Not only iron (rust)
• Coins
• Penny used to be just Copper, but now Zinc is
  also in it
• Zoom in on a Penny

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Timeline of the Penny

• 1783 to 1837- A penny was pure copper.
• 1837 to 1857- The cent was made of bronze (95
  percent copper, and five percent tin and zinc).
• 1857- The cent was 88 percent copper and 12
  percent nickel, giving the coin a whitish
  appearance.
• 1864 to 1962- The cent was again bronze (95
  percent copper, and five percent tin and zinc)
• except In 1943, the coin's composition was
  changed to zinc-coated steel.  This change was
  only for the year 1943 and was due to the
  critical use of copper for the war effort. 
• In 1962, the cent's tin content, which was quite
  small, was removed.  That made the metal
  composition of the cent 95 percent copper and 5
  percent zinc.
• 1982- when the composition was changed to 97.5
  percent zinc and 2.5 percent copper
  (copper-plated zinc). 

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• Most metals have 1, 2, or 3 valence e-.
• Therefore, most metals will lose e- when they
  bond becoming positively charged ions.

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Metallic bonding

• A metallic bond is an attraction between a
  positive metal ion and the electrons surrounding
  it.
• A metal or metal alloy consists of positively
  charged metal ions embedded in a sea of valence
  electrons.

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Synthetic elements

• Recall
• Elements 1-92 In Nature
• Elements 93 and above Synthetic (Man-made)
• Video-
• Colliders

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Chemical Bonds
Ionic Bonds
Covalent Bonds
Metallic Bonds
What is it?
What is it?
What is it?
In ________
Between ________
Between ________
Example/ Types
Example
Example
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Chemical Bonds
Ionic Bonds
Covalent Bonds
Metallic Bonds
Transfer of electrons
Bond between a positive metal ion and its e-
Sharing of electrons
Between nonmetals and metals
Between Nonmetals
In Metals
Polar- HF Nonpolar- H-H
Fe
NaCl
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After Quiz

• Make list of Elements Hydrogen ? Argon (1-18) to
  memorize for quiz next week (put in notebook!!)
• You will need to know the symbol and name
• Chapter 5 Review p. 179-180 1-25 (omit 19)