Transcript MOLECULAR MADNESS - Mona Shores Public Schools
Atomic Theory Practice Name the element: 1.
Na 23 11 Sodium 2.
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32 16 Sulfur 3.
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14 6 4.
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39 19 + Carbon-14 Potassium ion 5.
Group IIA, Period 3 Magnesium 6.
1s 2 2s 2 2p 5 Fluorine
MOLECULAR MADNESS
Bonding, Shape, Polarity & Reactions
ATOMIC THEORY
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Atoms composed of subatomic particles Protons + Nucleus Atomic # Unchangeable Neutrons 0 Nucleus Atomic mass – atomic # Isotopes Electrons Orbitals Atomic # Ions
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Cation +
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Less e-
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Anion –
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More e-
Exothermic
(heat emitting, i.e. chem warm up :)
Exercise #1
A. Draw the Lewis structure for Carbon.
B. Why do atoms bond with one another?
To fill their valence shell (Octet Rule) C. What are the 2 main types of intramolecular bonds?
1. Ionic – transfer electrons 2. Covalent – share electrons
BONDING
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Ionic Bonds
Transferred electrons
Formed between metals & nonmetals
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Metals = + cations w/full valence Nonmetals = - anions w/full valence Opposing charges attract STRONGLY Ionic Compounds
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High melting pts
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Good electrical conductors in solution
Ionic Bonding - Lewis Dot structures
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html
BONDING
Covalent Bonds – shared electrons
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Non-polar Covalent e- shared equally atoms w/similar electronegativities
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Polar Covalent e- shared Unequally atoms w/different electronegativities
http://iws.collin.edu/biopage/faculty/mcculloch/1406/outlines/chapter%202/chap02.html
Covalent Bonding - Lewis Dot structures Polar or Nonpolar Nonpolar?
Nonpolar?
Polar or Polar Nonpolar?
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html
Polarity in Molecules
Nonpolar Molecules
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Very little attraction between them Generally gases @ room temp
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Ex: CO 2
CO 2
Polar Molecules
• • • http://www.exo.net/~pauld/workshops/Greenhouse%20Effect/greenhouse.html
Have dipoles (ends with opposite charges) Electrons pulled toward more electronegative atom Attraction between dipoles of adjacent molecules
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Ex: H 2 O
http://www.chem1.com/acad/webtext/states/interact.html
http://www.chem.umass.edu/genchem/whelan/class_images/Structure_of_Water.jpg
VSEPR Theory
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Valence Shell Electron Pair Repulsion
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Outer shell e- pair up Arrange themselves as far apart from other pairs as possible since they repel other neg. charges
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Responsible for molecular shape
Sample Shapes Bent chemistry.gcsu.edu
http://www.chem.latech.edu/~upali/chem101/101MSJc8.htm
Bond Length
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Periodic Trend as you move down group and right to left within a period, bond length increases Radius & bond length increase
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Same as atomic radius
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Double & triple bonds are shorter than single
http://chemwiki.ucdavis.edu/Theoretical_Chemistry/Chemical_Bonding/Bond_Order_and_Lengths
Intermolecular Forces
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Hydrogen Bonds Formed between molecules whose atoms have extremely different electronegativities
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Most electronegative atoms: F, O, N bonded to
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Least electronegative atom: H Strong intermolecular force, causing high boiling points
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Not nearly as strong as INTRAmolecular bonds like covalent
Bonding Review
Endergonic (chem energy INTO your brain :) Exercise #1
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In textbook,
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Read p.275
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Answer the following questions from p.276-77:
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MC 1,2,6,10
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T/F 13,18 CM 22,24,26
Chemical Reactions
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Substances converted into NEW substances w/NEW properties Reactants – What goes in Products – What comes out Reactants Products Glucose + Oxygen
Carbon Dioxide + Water
Words
C 6 H 12 O 6 + O 2
CO 2 + H 2 O
Formulas
C 6 H 12 O 6 + 6O 2
6CO 2 C 6 H 12 O 6 (s) + O 2
(g)
CO 2 + 6H 2 O (g) + H 2
Balanced Equation
O(l)
Writing & Balancing Chemical Equations
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Going from word formula to balanced… 1.
Remember your naming rules!
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a.
a.
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Ionic compounds – cation (+) first then anion (-) # of + charges must equal # of charges Ex: Sodium + Chlorine
Sodium Chloride Na + + Cl -
NaCl Ex: Aluminum nitrate + Iron chloride
Iron Nitrate + Aluminum Chloride Al(NO 3)3 + FeCl 2
Fe(NO 3 ) 2 + AlCl 3
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Covalent compounds – use the number prefixes to indicate numbers of atoms Carbon + Chlorine
Carbon Tetrachloride C + 2Cl 2
CCl 4
Ions & Charges
Cations +1
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Group 1 atoms Ammonium
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NH 4 +1 +2
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Group 2 atoms Anions -1
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Group 7 atoms Chlorate = ClO 3 -1 Nitrate = NO 3 -1 Hydroxide = OH -1 -2
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Group 6 atoms Sulfate = SO 4 2 Carbonate = CO 3 -2 -3
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Group 5 atoms Phosphate = PO 4 -3
Naming & Writing Gases & Acids Gases
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The name of the element followed by the word gas is always a diatomic molecule
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Ex: Oxygen gas = O 2 Ex: Chlorine gas = Cl Ex: Hydrogen gas = H 2 2 Acids
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The name of an ion followed by the word acid means you add the appropriate # of H’s in front of the ion
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The # of H’s equals the
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Ex: Hydrochloric acid = HCl Ex: Sulfuric acid = H 2 charge of the anion SO Ex: Phosphoric acid = H 4 3 PO 4
Types of Chemical Reactions 1.
2.
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Synthesis Reaction aka direct combination reaction
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2 or more reactants come together to form a single product A + B
AB 2Na + Cl 2
2NaCl
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Decomposition Reaction Single compound broken down into 2 or more smaller products
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AB
A + B 2H 2 O
2H 2 + O 2
Types of Chemical Reactions 3.
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Single Replacement Reaction Uncombined element takes the place of another element within a compound
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A + BX Mg
AX + B + CuSO 4
Mg SO 4 + Cu More active elements replace less active ones Activity level shown in activity series If uncombined element NOT more active, then no reaction takes place
Types of Chemical Reactions 4.
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Double Replacement Reaction Atoms or ions from 2 different compounds replace each other
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AX + BY CaCO 3
AY + BX + 2HCl
CaCl 2 + H 2 CO 3