Transcript Stability in Bonding Section 19.1 Stability in Bonding  Statue of Liberty is greenmade out of copper  Copper reacts with sulfur and oxygen 

Stability in Bonding
Section 19.1
Stability in Bonding
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Statue of Liberty is greenmade out of copper
 Copper reacts with sulfur and oxygen
 Reactants: Copper, oxygen, sulfur, carbon dioxide, water
 Products: Cu4SO4(OH)6, Cu2CO3(OH)3, Cu3(CO3)2(OH)2
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Properties of the elements are very different than
properties of the compounds in a chemical reaction
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Hydrogen + oxygen  Water
Colorless gases
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Colorless liquid
Flammable Supports combustion  Puts out fires
Chemical Formulas
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Chemical Formula- tells how many of each
element are present in a compound
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Consists of element symbols and subscripts
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Water has 2 hydrogen atoms and 1 oxygen atom
What do the formulas mean?
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SiO2
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silicon- 1 Oxygen-2
C12H22O11
Carbon- 12 Hydrogen-22 Oxygen-11
N2O
Nitrogen- 2 Oxygen-1
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Why do compounds form?
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Atoms combine because the compound is more
stable than the individual elements
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Noble gases don’t form compounds because
they are stable
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They have the wrong number of electrons to be
stable alone and must share or exchange electrons
Chemically stable- have 8 valence electrons
Valence electrons- outer energy level electronsthe electrons that determine chemical properties
Valence electrons
# at the top is valence
Except for He, which has only 2
Stability
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Hydrogen, helium, lithium, beryllium, and boron need
2 valence electrons in their outer energy level to be
stable
Others need 8 to be stable – usually.
Electron dot diagrams- include the element symbol
and dots to represent valence electrons
Can use electron dot diagrams to help us determine
stability
H is less stable than He because it has only 1 valence
electron while He has 2 valence electrons
How do atoms become stable?
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They share, gain, or lose electrons to become
stable
Chemical bond- force that holds atoms together
in a compound – caused by either exchanging or
sharing electrons