Chemical Bonding Unit 5
Today… • Turn in: • Sodium Party Reading Test (basket) • Goal Sheet (add test and find totals) • If you do not meet your goal write 2 things you’d do differently • Our Plan: • New Calendar • Pre-Lab • Complete Inquiry Lab • Wrap Up – Let’s Make a Venn Diagram • Homework (Write in Planner): • Lab due next class
Today… • Turn in: • Get out your Lab & Note Booklet • Our Plan: • Lab Discussion/Notes • Find Someone Who • Crash Course Video • Notes – Ionic Bonds • Complete Worksheet #1 • Wrap Up – Clicker Review • Homework (Write in Planner): • Worksheet #1 due Next Class
Ionic Compounds • Properties: • Hard • Crystalline Solids • Brittle • Water-soluble • High melting point • Can conduct electricity
Molecular Compounds • Properties: • Soft, hard, or flexible • Usually less water-soluble • Lower melting points • Cannot conduct electricity
Melting Point • Ionic compounds have a higher melting point because there is such a strong attraction in the bonds. • It takes a higher temperature (more energy) to break them.
Conducting Electricity • Ionic compounds are able to conduct electricity because they contain ions (charged particles). • Electricity is the movement of electrons and the ions spread out in solution and allow electricity to be transferred. • Hairdryer in the bathtub example
Lab Analysis • How does your Venn diagram compare to the true properties? • Discuss with your team.
Find Someone Who • Move around the classroom to find students who can answer the questions on your handout. Write their answer and obtain their initials. You can not have the same student answer more than one question for you.
Crash Course Intro • http://www.youtube.com/watch?v=QXT4OVM4vXI • To 1:30
Compound • A combination of two or more elements • Elements form compounds because they want to be stable.
Types of Compounds • There are three major types of compounds: • Ionic • Molecular • Metallic • Ionic compounds are made up of ionic bonds, molecular compounds are made up of covalent bonds, metallic compounds are made up of metallic bonds.
Types of Compounds • Ionic Compounds – Metal & Nonmetal • Molecular/Covalent Compounds – Nonmetals Only • Metallic Compounds – Metals Only
Try It Out • Which type of compound is: • NaCl • H2SO4 • PCl5 • K2S
Valence Electrons • An atom’s outer electrons • They are the ones that are available to be lost, gained, or shared in a chemical bond
Valence Electrons • The number of valence electrons corresponds to an atom’s group number! • They are labeled at the bottom of each column on your PT (1 e-, 2 e-, etc.)
Remember? • The Octet Rule – Eight is Great, Except for Hydrogen and Helium, Two will Do! • Atoms gain, lose, or share electrons (BOND) so that they have an octet
Electron Dot Structures • An element’s symbol with it’s valence electrons drawn around it
Electron Dot Notation • To Draw: • Write the element’s symbol • Draw a dot for each valence electron around the symbol • Draw the dots singly before doubling them up (Hund’s Rule)
Electron Dot Notation • After you write the symbol, the areas around the symbol represent the orbitals and axis: s orbital S px orbital pz orbital py orbital
Example • Carbon Carbon can make 4 bonds for a total of 8 electrons! C
Example • Aluminum Al How many bonds can Al make? 3
Example • Bromine Br How many bonds can Br make? 1
Try it Out! • Nitrogen • Krypton N How many bonds can N make? 3 How many bonds can Kr make? 0 Kr
Ionic Bonds • Bond in which one atom gains an e- & one loses an e- • Between a cation & an anion
Ionic Bonds • Bonds are made when opposite charges are attracted to one another by electrostatic forces • Though ionic compounds are made from ions (charged particles) they are electrically neutral • The total charge of the compound is 0
Ionic Bond cost.georgiasouthern.edu/. ../molecule/polar.htm
Chemical Formula • The subscripts in the formula tell you how many atoms of each element are present in the compound. • H2O – 2 Hydrogens + 1 Oxygen • C6H12O6 – 6 Carbons + 12 Hydrogens + 6 Oxygens • NaCl – 1 Sodium + 1 Chlorine
EXAMPLE – don’t write words, just pictures • Lithium + Bromine Li Br • Draw the electron dot structure for each element.
EXAMPLE • Lithium + Bromine Li Br • Draw an arrow to show the transfer of electrons and move the electron to its new location.
EXAMPLE • Lithium + Bromine Li+1 Br-1 LiBr • Determine the charge for each ion and write the formula.
Try it Out! • Calcium + 2 Fluorine F Ca F • Draw the electron dot structure for each element.
Try it Out! • Calcium + 2 Fluorine F F Ca • Draw an arrow to show the transfer of electrons and move the electron to its new location.
Try it Out! • Calcium + 2 Fluorine Ca+2 F-1 CaF2 • Determine the charge for each ion and write the formula.
Metallic Bonds • Best characterized by the phrase, “a sea of electrons” • The valence electrons are mobile and can drift freely from one part of the metal to another
Metallic Bonds • The fact that electrons flow freely helps to explain some of the characteristics of metals: • Good conductors • Malleable • Ductile
Alloys • Mixtures composed of two or more elements, at least one of which is a metal • Their properties are often superior to those of their component elements • Examples: • Sterling Silver – 92.5% silver, 7.5% copper • Bronze – 7 parts copper : 1 part tin • Steel – Iron, Carbon, and small amounts of B, Cr, Mn, Mo, Ni, W, V
STOP! • Complete Worksheet #1 • Use the “helpful hints” handout in your packet to complete #4
Wrap Up • Clicker Review
Today… • Turn in: • Worksheet #1– get out to check • Draw the structures for the bonding that occurs between Barium and 2 Iodines on the bottom of your worksheet. Include ions and formula. • Our Plan: • Notes – Covalent Compounds & Lewis Structures • Begin Worksheet #2 (you can work on it again on Monday) • Wrap Up – Pass the Paper Review • Homework (Write in Planner): • Work on Worksheet
Molecular Compounds • Covalent- sharing of electrons (tug of war) • non polar covalent • polar covalent
Covalent Bond cost.georgiasouthern.edu/. ../molecule/polar.htm
Formulas • Molecular Formula – Shows how many atoms of each element a molecule contains • Diatomic Molecule – molecule consisting of two of the same atom (O2) • The formula does not tell you about a molecule’s structure