Welcome Back!! This semester… January- Bonding and Naming Ionic and Covalent Compounds Jan/February- Finish Bonding & Reactions After Feb. break- Stoichiometry March/April- Thermo, Gases April- Acids and Bases May- Solutions & Final Exam Review

Chemical Bonding and Nomenclature

Valence electrons The electrons in the highest energy level of an atom. s and p electrons* *d electrons are never valence electrons Total # of s and p electrons in a “FULL” energy level = 8 (THE OCTET RULE)

Lewis Structures We include only valence electrons Water How many valence electrons?

LEWIS DOT STRUCTURES FOR THE FIRST 20 ELEMENTS

Bonding Chemical bond: A force that holds groups of two or more atoms together and makes them function as a unit Fundamental types of bonds Ionic Covalent Metallic Bonds form in order to achieve a full outer shell (8) of electrons to: Decrease potential energy (PE) Increase stability

Ionic bonding Described as a TRANSFER OF ELECTRONS Takes place between metals and nonmetals. Nonmetals “want” electrons and metals “want” to give electrons away. Atoms become ions by gaining or losing electrons Oppositely charged ions are attracted to one another: this attraction is an “ionic bond.” Results in an ionic COMPOUND

Metals and Nonmetals Create Ionic Bonds

Ions Cation Positively charged Atom has LOST one or more electrons Metals tend to become cations Anion Negatively charged atom has GAINED one or more electrons Nonmetals tend to become anions

Types of ions Monatomic ion Cation or anion that consists of a single type of element Ex: Li +, Br - Polyatomic ion 2 or more elements that are combined, but act as a single ion (or particle) Ex: CO 3 2- or NH 4 +

Formula units Ionic compounds are represented by formula units: similar to “molecule” except ionic compounds exist as a 3D network of multiple formula units because of the electrostatic attraction of opposite charges. The lowest whole number ratio of ions in an ionic compound is a formula unit. NaClCaO MgCl 2 Al 2 O 3

Types of ionic compounds COMPOUND Ternary Compound Binary Compound 2 elements more than 2 Elements  Means there is a Polyatomic ion present NaNO 3 NaCl

Rule of Zero Charge The charges on the metal cations (+) and nonmetal anions (-) add up to zero. Ex: Na + and Cl - add up to an overall charge of zero, so the formula unit is NaCl Ex: Ca 2+ and O 2- add up to an overall charge of zero, so the formula unit is CaO

Writing Binary Ionic Compounds RULES: ****Cation always listed first**** 1.Drop Charges 2.Criss Cross Apple Sauce 3.Reduce (simplify) subscripts if needed Na + and Cl -  NaCl RULES: ****Cation always listed first**** 1.Drop Charges 2.Criss Cross Apple Sauce 3.Reduce (simplify) subscripts if needed Na + and Cl -  NaCl

What if the charges are opposite, but not equal??? Criss-cross the charge values to subscripts Ex: Al 3+ + O 2- is represented as Al 2 O 3 Ex: Mg 2+ + Cl - is represented as MgCl 2 But why? Because the overall charge must be zero All atoms “want” a full valence

Naming Binary ionic compounds 1.List name of cation If metal cation is not a transition element, give it the same name as the element and move on to anion. If cation can have more than one charge (i.e. most transition metals), use roman numerals in parentheses to specify charge. For Example: Iron has 2 common oxidation states (charges): Fe 2+ and Fe 3+ Fe 2+ would be iron (II) Fe 3+ Would be iron (III) For Example: Iron has 2 common oxidation states (charges): Fe 2+ and Fe 3+ Fe 2+ would be iron (II) Fe 3+ Would be iron (III) CaO Fe 2 O 3

Naming Binary ionic compounds Name the cation first Name the anion last; for binary compounds, it always ends in –ide. Examples: CaO would be calcium oxide Fe 2 O 3 is iron (III) oxide NaCl is sodium chloride AgCl is silver chloride

Common anion endings P- phosphideF-fluoride O-oxide Br- bromide S- sulfideI- iodide Cl-chlorideC- carbide N-nitride P- phosphideF-fluoride O-oxide Br- bromide S- sulfideI- iodide Cl-chlorideC- carbide N-nitride

Some common polyatomic ions

Polyatomic Ions- QUIZ Friday!! Add these to your list: bromate, BrO 3 -bromate, BrO 3 - iodate, IO 3 -iodate, IO 3 - thiocyanate, SCN -thiocyanate, SCN - hydrogen carbonate, HCO 3 - (also called bicarbonate)hydrogen carbonate, HCO 3 - (also called bicarbonate) hydride, H - is NOT part of the list to memorize THERE ARE 26 to memorizeTHERE ARE 26 to memorize

Naming polyatomic anions: these just have to be memorized! With anions that end in oxygen, if you know one, you can figure out the other! # of oxygensnaming convention 1 less (PO 3 3- ) ends in –ite(phosphite) 1 more (PO 4 3- ) ends in –ate(phosphate) Notice that within one group of polyatomic ions, the charges are the same!

Writing formulas for ternary compounds If more than 1 of a polyatomic ion is present, write parentheses around any polyatomic ion and add subscripts to the outside of the parentheses. Never change the subscript of a polyatomic ion (it will change the composition of the ion): Ca(OH) 2, Ca 3 (PO 4 ) 2 Include the subscript inside the parentheses

Naming ternary ionic compounds For a monatomic cation and polyatomic anion, write both names together; do not change them in any way Ex: Na 2 SO 4 is sodium sulfate For a polyatomic cation with a monatomic anion, write the polyatomic ion’s name first, then the monatomic root with the –ide ending Ex: NH 4 Cl is ammonium chloride

Metallic Bonding Metals form lattices but do not lose, gain, or share e - Outer e - shells overlap = electron sea model e - are free to move = delocalized e - making a metallic cation Metallic bond: attraction of a metallic cation for delocalized electron Properties of metals: melting point varies greatly, malleable, ductile, good conductors

Sea of electrons

Ionic Metallic Electron sea model – delocalized electrons attracted to metal cations Malleable, ductile, lustrous, colorful Conducts electricity Overall highest MP of 3 types All bonding involves valence electrons Both involve metals Oppositely charged ions attracted to each other (cations and anions)Oppositely charged ions attracted to each other (cations and anions) Metals with non-metalsMetals with non-metals Brittle, dull solidsBrittle, dull solids Only conducts electricity as electrolytesOnly conducts electricity as electrolytes Generally, medium MP of 3 typesGenerally, medium MP of 3 types

Covalent bonding

Covalent bonds Occur between atoms that are “sharing” electrons Form covalent compounds

QUIZ: 1-5, NAME THE COMPOUND… 6-10, WRITE THE FORMULA 1) SrO 2) NaClO 3 3) AlF 3 4) NH 4 OH 5) Fe 3 (PO 3 ) 2 6) barium nitrite 7) potassium chloride 8) manganese (II) iodide 9) copper (II) acetate 10) sodium carbonate