Atomic Theory Practice Name the element: Na2311 ?3216 ?146 ?3919+ Group IIA, Period 3 1s22s22p5 Sodium Sulfur Carbon-14 Potassium ion Magnesium Fluorine

Bonding, Shape, Polarity & Reactions MOLECULAR MADNESS Bonding, Shape, Polarity & Reactions

ATOMIC THEORY Atoms composed of subatomic particles Protons Neutrons Electrons + - Nucleus Orbitals Atomic # Atomic mass – atomic # Unchangeable Isotopes Ions Cation + Less e- Anion – 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? C. What are the 2 main types of intramolecular bonds? To fill their valence shell (Octet Rule) Ionic – transfer electrons Covalent – share electrons

BONDING Ionic Bonds Transferred electrons Formed between metals & nonmetals Metals = + cations w/full valence Nonmetals = - anions w/full valence Opposing charges attract STRONGLY Ionic Compounds High melting pts 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 Non-polar Covalent e- shared equally atoms w/similar electronegativities 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 Polar or Nonpolar? Nonpolar Polar or Nonpolar? Polar http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html

Polarity in Molecules Nonpolar Molecules Polar Molecules Very little attraction between them Generally gases @ room temp Ex: CO2 Polar Molecules Have dipoles (ends with opposite charges) Electrons pulled toward more electronegative atom Attraction between dipoles of adjacent molecules Ex: H2O CO2 http://www.exo.net/~pauld/workshops/Greenhouse%20Effect/greenhouse.html http://www.chem1.com/acad/webtext/states/interact.html http://www.chem.umass.edu/genchem/whelan/class_images/Structure_of_Water.jpg

VSEPR Theory Valence Shell Electron Pair Repulsion Sample Shapes Outer shell e- pair up Arrange themselves as far apart from other pairs as possible since they repel other neg. charges Responsible for molecular shape Sample Shapes chemistry.gcsu.edu Bent

Bond Length Periodic Trend http://www.chem.latech.edu/~upali/chem101/101MSJc8.htm Periodic Trend as you move down group and right to left within a period, bond length increases Same as atomic radius Double & triple bonds are shorter than single Radius & bond length increase http://chemwiki.ucdavis.edu/Theoretical_Chemistry/Chemical_Bonding/Bond_Order_and_Lengths

Intermolecular Forces Hydrogen Bonds Formed between molecules whose atoms have extremely different electronegativities Most electronegative atoms: F, O, N bonded to Least electronegative atom: H Strong intermolecular force, causing high boiling points Not nearly as strong as INTRAmolecular bonds like covalent

Bonding Review

Endergonic (chem energy INTO your brain :) Exercise #1 In textbook, Read p.275 Answer the following questions from p.276-77: MC 1,2,6,10 T/F 13,18 CM 22,24,26

Chemical Reactions Reactants – What goes in Products – What comes out Substances converted into NEW substances w/NEW properties Reactants – What goes in Products – What comes out Reactants Products Glucose + Oxygen  Carbon Dioxide + Water C6H12O6 + O2  CO2 + H2O C6H12O6 + 6O2  6CO2 + 6H2O C6H12O6(s) + O2(g)  CO2(g) + H2O(l) Words Formulas Balanced Equation Complete Equation

Writing & Balancing Chemical Equations Going from word formula to balanced… Remember your naming rules! 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(NO3)3 + FeCl2  Fe(NO3)2 + AlCl3 Covalent compounds – use the number prefixes to indicate numbers of atoms Carbon + Chlorine  Carbon Tetrachloride C + 2Cl2  CCl4

Ions & Charges Cations +1 Group 1 atoms Ammonium NH4+1 +2 Anions -1 Group 7 atoms Chlorate = ClO3-1 Nitrate = NO3-1 Hydroxide = OH-1 -2 Group 6 atoms Sulfate = SO4-2 Carbonate = CO3-2 -3 Group 5 atoms Phosphate = PO4-3

Naming & Writing Gases & Acids The name of the element followed by the word gas is always a diatomic molecule Ex: Oxygen gas = O2 Ex: Chlorine gas = Cl2 Ex: Hydrogen gas = H2 Acids The name of an ion followed by the word acid means you add the appropriate # of H’s in front of the ion The # of H’s equals the - charge of the anion Ex: Hydrochloric acid = HCl Ex: Sulfuric acid = H2SO4 Ex: Phosphoric acid = H3PO4

Types of Chemical Reactions Synthesis Reaction aka direct combination reaction 2 or more reactants come together to form a single product A + B  AB 2Na + Cl2  2NaCl Decomposition Reaction Single compound broken down into 2 or more smaller products AB  A + B 2H2O  2H2 + O2

Types of Chemical Reactions Single Replacement Reaction Uncombined element takes the place of another element within a compound A + BX  AX + B Mg + CuSO4  MgSO4 + 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 Double Replacement Reaction Atoms or ions from 2 different compounds replace each other AX + BY  AY + BX CaCO3 + 2HCl  CaCl2 + H2CO3