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Bonding Unit 4, Day 3 12/09/14 Door SMARTBOARD Door SMARTBOARD Go to your ASSIGNED seat!! Go to your ASSIGNED seat!! Door SMARTBOARD Bonding WEEK 15 12/09/14 CATALYST Can two anions form an ionic bond? Why or why not? Have out on your desk: • Binder • Sheets from front *Answer in complete sentences! Homework: Ionic bonding practice 0:01 0:02 0:03 0:04 0:05 0:06 0:07 0:08 0:09 0:10 0:11 0:12 0:13 0:14 0:15 0:16 0:17 0:18 0:19 0:20 0:21 0:22 0:23 0:24 0:25 0:26 0:27 0:28 0:29 0:30 0:31 0:32 0:33 0:34 0:35 0:36 0:37 0:38 0:39 0:40 0:41 0:42 0:43 0:44 0:45 0:46 0:47 0:48 0:49 0:50 0:51 0:52 0:53 0:54 0:55 0:56 0:57 0:58 0:59 1:00 1:01 1:02 1:03 1:04 1:05 1:06 1:07 1:08 1:09 1:10 1:11 1:12 1:13 1:14 1:15 1:16 1:17 1:18 1:19 1:20 1:21 1:22 1:23 1:24 1:25 1:26 1:27 1:28 1:29 1:30 1:31 1:32 1:33 1:34 1:35 1:36 1:37 1:38 1:39 1:40 1:41 1:42 1:43 1:44 1:45 1:46 1:47 1:48 1:49 1:50 1:51 1:52 1:53 1:54 1:55 1:56 1:57 1:58 1:59 2:00 End 4 … Bonding Ionic bonding 12/09 Bonding 12/09/14 Learning Intention: We will demonstrate knowledge of ionic bonding. Success Criteria: We will be successful when we model the bonding relationships that would occur between various elements. Today’s Agenda Lake sturgeon Ionic bonding NOTES Homework time Lots of work today! Let’s ROCK! Lake sturgeon bowl participants!!! Meet TODAY after school in this room (326) for a brief informational meeting! Anyone who wants to participate but can not stop by? GET PUMPED Must know this! Lewis Structures Atoms and ions may be represented by Lewis structures Models that show ONLY the valence electrons Electrons are represented by dots surrounding the element symbol. Electrons are typically paired. Example: Oxygen Practice: Draw the following Lewis Structures Aluminum Lithium Bonding Chemical Bond: two or more atoms sharing or transferring electrons in order to link the elements together to create a compound or molecule Octet Rule: atoms want to have an electron configuration the same as a noble gas (8 valence electrons). This means atoms will give up or share electrons in order to achieve this configuration. Types of bonds… 1) Ionic: electron is transferred from one atom to another 2) Covalent: electron(s) are shared between two atoms Ionic Bonding & Nomenclature When ionic bonds are formed, valence electron(s) are transferred from the atom with lesser electronegativity to the one with greater electronegativity Electronegativity is the tendency of an atom to attract an electron. Must follow the octet rule during bonding Remember! Ions are formed by gaining or losing electrons! Unless the overall compound has a charge, make sure all of the charges of cations balance out the charges of your anions. Example: Formation of sodium sulfide (Na + S _______) 1. Identify the charge of each component based on its location in the periodic table. 2. Example: Formation of sodium sulfide (Na + S _______) Balance the charges so that the total charge of the compound is 0. Criss-cross method: the charge of the cation will be equal to the number of anions you have and the charge of the anion will be equal to the number of cations you have. If they have the same number, you do not need to do this! Example: Formation of sodium sulfide (Na + S _______) 3. Use the balanced numbers as subscripts to identify how many of each atom are in the compound (you do not need to identify with subscripts if there is only one of the atom in the compound) Practice: Write the formula for each compound Potassium + Chlorine Potassium Chloride Magnesium Aluminum + Chlorine Magnesium Chloride + Sulfur Aluminum Sulfide Ionic Lewis Structures Use Lewis structures to show the movement of electrons and the bonds they form. Note: The central atom is the one with the lowest electronegativity Ex: Draw the Lewis Structure for NaCl 1. Draw the Lewis structure for each of the atoms 2. Identify how the electrons move in order to form the bond Draw each atom with its new electrons & charge 3. Practice: Draw the Lewis structure for the following ionic compounds MgCl2 You try! NaF Al2S3 FYI! Polyatomic Ions Poly = Many Atomic = Atoms Multiple atoms that make up a specified ion that forms ionic compounds See list of polyatomic ions! Example: Write the formula for calcium hydroxide 1. Identify the ions present and their charges Ex: Write the formula for calcium hydroxide 2. Balance the charges 3. Use the balanced charges as the subscripts for the compund **Be sure if you have multiples of the polyatomic ion that the whole ion is in parentheses with the subscript outside of the parentheses! Practice Write the formula! Sodium Carbonate Potassium Permanganate Homework time! Quietly complete as much as you can. Work with your neighbor. Before asking Ms. Schuld 1) Check with a classmate 2) Consult your notes You ROCK :) Tomorrow = Nomenclature of ionic compounds! Nomenclature: scientific term for naming Bonding! https://www.youtube.com/watch?v=_M9khs87xQ8 https://www.youtube.com/watch?v=NgD9yHSJ29I http://www.pbslearningmedia.org/resource/lsps07. sci.phys.matter.chembonds/chemical-bonds/ Lab review! 12/09/14 On a Tuesdayyyy Success Criteria Question In order for an ionic compound to be formed, what must occur? Nomenclature for Ionic Compounds Nomenclature: scientific term for naming Type I Ionic Compounds Compounds that contain a metal cation and a non-metal anion 1. 2. 3. Cation is named first. Cation takes its name directly from its element. Anion is named second. Replace the suffix of the anion with “-ide” Write the name all together Example: NaCl 1. Cation is named first. Cation takes its name directly from its element. Anion is named second. 2. Replace the suffix of the anion with “-ide” 3. Write the name all together Compounds that contain a Typecation II Compounds metal with no fixed charge, and a non-metal anion The cation is named the same way as type I, but now a Roman numeral is used in order to designate the charge of the metal Ex. Iron (III) for Fe3+ vs. Iron (II) for Fe2+ The anion is written the same way as type I – take the root of the element and replace the suffix with “-ide” Example: Name the compound HgO 1. Cation is named first. Cation takes its name directly from its element. Anion is named second. 2. Determine the charge of the anion to help you identify the charge of the cation Example: Name the compound HgO 3. Write the name of the cation with the roman numeral 4. Write the name of the anion following the cation and roman numeral, making sure the suffix is replaced with “-ide” Name the following compounds. 1. 2. 3. CuI2 AuCl3 Ag2S Properties of Ionic Compounds Form crystals Very hard – each ion is bonded to several oppositely charged ions High melting points Brittle Conduct electricity when Covalent Bonding and Nomenclature Covalent Bonding: electrons are shared between two atoms, creating a chemical connection between the two atoms Rather than having charges that attract two atoms together, it is the mutual need of additional electrons to fulfill their octet Atom H Electrons Electrons Needed Electron in Outer To Fill Pairs Shell Outer Shared Shell 1 1 1 Cl 7 1 1 O 6 2 2 N 5 3 3 C 4 4 4 S 6 2 2 Lewis structures are used to represent these compounds Lines connecting the atoms show that the pairs of electrons are being shared between the two atoms Must always follow octet rule When counting, lines count as 2 electrons for each atom Three main types of covalent bonds Single: when two atoms share a single pair of electrons Example: F2 Each fluorine is missing one electron, so they share a pair of electrons, making both outer shells full Three main types of covalent Double: bondswhen two atoms share two pairs of electrons Example: O2 Each atom has 6 valence electrons, so if each atom shares two electrons with the other, then both atoms’ valence shells will be full Three main types of covalent Triple: when two bonds atoms share three pairs of electrons Example: N2 Each atom has 5 valence electrons, if each atom shares three electrons with the other its need for additional electrons will be satisfied. Bonding between different elements 1. Determine how many electrons each element needs to fill the octet rule Different elements have different needs! This is solved the same way as when atoms had different charges. The crossover rule still works! Example: make a compound where oxygen and hydrogen are covalently bonded Oxygen needs 2e Hydrogen needs 1e We need 2 hydrogen for every 1 oxygen OR you could use 2 oxygen and 2 hydrogen Helpful Hints 1. 2. 3. The atoms that need the most electrons should be placed in the center The atoms that need the fewest electrons should be placed around the ones that need most Attempt to satisfy octets with single bonds before making double or triple bonds Draw Lewis Structures for the following compounds CCl4 CO2 SO2 Nomenclature: Type III NonMetal Compounds This is only for compounds containing only non-metals! Covalently bonded 1. 2. 3. The less electronegative atom is named first, then the more electronegative The suffix of the more electronegative atom is replaced with “-ide” The number of atoms of each element is given a Greek prefix ** If there is only one of the less electronegative atom, then you do not have to add the monoprefix 1. Example: Name the The less electronegative compound CCl4 atom is named first, then the more electronegative 2. The suffix of the more electronegative atom is replaced with “-ide” 3. The number of atoms of each element is given a Greek prefix Polar Covalent Compounds Polar covalent bonds occur when the difference in electronegativity is 0.5-1.5 Electrons are shared unequally between atoms The atom with the greater electronegativity will pull the electrons closer to it, therefore causing the compound to be polar Example: Water Properties of Covalent Compounds May be solid, liquid or gas at room temperature Tend The to be soft solids more atoms that each compound has, the higher the melting point will be Brittle Poor conductors of heat and electricity VSEPR: Valence Shell Electron Theory Covalent bonds and lone pair electrons like to stay as far apart from each other under all conditions The shape of the molecule (molecular geometry) is determined by how many bonding and non-bonding electron pairs there are. This identifies the overall shape, and the angles between the bonds Steps to Predict Molecular Geometry 1. 2. Draw the Lewis Structure Count the number of lone pairs there are in the compound Double 3. 4. and triple bonds count as 1! Count the number of bonds there are in the compound Use the reference table to predict geometry Example: Predict the shape of H2 O 1. Draw the Lewis structure of the compound 2. Count the number of lone pairs there are in the compound 3. Count the number of bonds there are in the compound 4. Use the table for reference to determine the geometry. Review: IONS When atoms will lose electrons they become cations When atoms will gain electrons they become anions 2 Na Mg 2 S Cl Steps for ions: 1. 2. 3. 4. Find number of valence electrons Determine how many electrons the element will gain or lose to get to 0 or 8 Write that number as a superscript on the right side of the ion Add a + after if positive or a – after if negative Potassium (K) Carbon Iodine (I) Review: Ionic Charge + Na The Ionic Charge for an atom is the charge on the atom (how many electrons it gains or loses) What is the Ionic Charge for the following ions? 2O 2+ Ca 3B + K Ionic Bonds Ionic bonds are bonds between cations & anions If atoms transfer e- to create opposite ions, the opposite charges attract and form an ionic bond Example! Na+ + Cl- NaCl (sodium chloride = salt!) Key Question… Why do atoms transfer electrons in the first place? (Why would they want to gain or lose electrons?) Octet Rule! Atoms want ________ electrons in their outermost shell! They will be happy when they have 8 valence electrons! (Or if they are closer to the atomic structure of He they will be satisfied with 2) So which elements bond with which?! Cations and Anions come together to make compounds! Example from yesterday’s lab! Chlorine and calcium ions came together to form calcium chloride. 2+ Ca + 2Cl CaCl2 But where does that 2 come from?!!?! Criss-Cross Method 1. 2. 3. 4. 5. List the Metal first, non-metal second. Write the ionic charge above the symbol. Criss-cross the numbers. (a 1 does not need to be written, drop the + or -) Final answer lists only the subscripts (numbers below the line) If they are the same number, they cancel out IE: Combine hydrogen and chlorine IE: Now magnesium and fluorine Charges must be balanced! Na+ + Cl- NaCl Mg2+ + F- + F- MgF2 Predict the compound! Na and O Ca and S Be and F Missing safety contracts!!! Alfredo LJ Famo Thandi Christian Constance Demond Alejandro Emileye Tara Josh Jazmin Daisy Juana. Jubi Hehehehe http://www.huffingtonpost.c om/2014/02/19/alanandersen-bacontfm-iceslip_n_4816325.html The families of the periodic table Alkalai Metals: Group 1 Have a low density, low melting point, are good conductors, and are extremely reactive with oxygen, water and other halogens The families of the periodic table Alkalai Earth Metals: Group 2 Have very similar properties to group 1, however slightly less reactive The families of the periodic table Halogens: Group 17 All metals, and diatomic Diatomic: always found bonded to another atom The families of the periodic table Noble Gases: Group 18 Inert (unreactive) because their electron shells are full, making it almost impossible for these elements to react with others Why to we care about any of this?? To understand this! http://www.nuffieldfoundation.org/practicalchemistry/ammonium-dichromate-volcano Ammonium dichromate