Demo Salt Crystal (hanging on ceiling) Unit 5 Bonding Lesson 1 – Ionic Bonds Demo Salt Crystal (hanging on ceiling) Videodisk Unit 3

Lewis Dot Diagrams Review A way of showing atoms and how they bond Atoms are represented by an atomic symbol with its valence electrons Valence electrons depend on family Li: 1s2, 2s1 N: 1s2, 2s2, 2p3 These are also called electron dot diagrams. Typically, transition elements have 2 valence electrons. Li N

The Octet Rule Atoms are most stable when their outermost shell is full Level 1 = 2 electrons All other shells = 8 electrons Noble gases have full outer shell so they don’t bond with anyone Other atoms lose, gain, or share electrons to get a full outer shell For atoms to become more stable, they must lose energy. Full outer shells cause them to become stable (lose energy).

Ionic Bonding Electrostatic attraction between ions of a metal and a nonmetal Valence electrons are lost by metal, gained by non-metal Cl Na NaCl Ionic compounds are actually lots of + ions and – ions sticking together. Properties High melting points, brittle, dissolves in water, good conductors when liquid or dissolved. Demo Salt Crystal Link to Ionic bond animation

Metals lose electrons to get a stable outer shell (revert back to 8) Nonmetals gain electrons to get a stable outer shell (add as many as needed until 8) K Cl Final charges must equal zero. K+ Cl- http://www.youtube.com/watch?v=5IJqPU11ngY

Properties of Ionic Compounds Most have high melting points and high boiling points. Many dissolve in water. Most are brittle. Good conductors of electricity if melted (molten) or dissolved. Form crystalline structures. Ionic bonds are usually strong and stable. If stressed, the bonds will break along a cleave line. Ionic bonds are very strong and stable. But if stressed, will break along a cleave line.

Metal Cations Type I Type II metals whose ions can only have one possible charge IA, IIA, (Al, Ga, In, Zn, Cd, Ag) determine charge by position on the Periodic Table IA = 1+, IIA = 2+, (Al, Ga, In = 3+; Zn & Cd = 2+; Ag = 1+) Type II metals whose ions can have more than one possible charge mostly transition metals, post-transition metals

Polyatomic Ions Polyatomic ions are made of more than one atom. Polyatomic ions are groups of atoms that travel together—never apart. The given charge is on the entire polyatomic ion—not on individual atoms within the polyatomic ion. A list can be found on page 7 of your reference packet. You are responsible for knowing: ammonium, cyanide, acetate, nitrate, nitrite, hydroxide, carbonate, sulfate, sulfite, phosphate You will have a quiz on the names, symbols and charges of these polyatomic ions.

Naming Type I Metals Ionic Compounds all names are composed of a cation (positive metal ion) and an anion (negative nonmetal ion or polyatomic ion) Cation (metal) is element name anion (nonmetal) is element name with –ide on the end or name of polyatomic ion KCl Potassium Chloride

Examples – Name the following NaCl MgO Li3PO4 NH4Cl Sodium Chloride Magnesium Oxide Lithium Phosphate Ammonium Chloride

Formulas for Ionic Compounds Balance the ions so the compound has a charge of zero Magnesium Fluoride Mg+2 F-1 We don’t typically write 1s. Simplest form=Formula unit MgF2 (Don’t Write 1s)

Formulas for Ionic Compounds Balance the ions to zero Silicon Sulfide Si+4 (need 1 = +4) S-2 (need 2 = -4) We don’t typically write 1s. SiS2 Simplest form = Formula unit

Examples – Find the formulas of: Calcium Oxide Aluminum Chloride Magnesium Nitrate Ca2+ O2- CaO Al3+ Cl- AlCl3 Mg2+ NO3- Mg(NO3)2

Extra Rules for Naming Ionic Compounds with a Type II Metal Ion Type II metals are named like normal but with a Roman Numeral to indicate charge of the metal Copper (I) = Cu+ Copper (II) = Cu2+ Name the following: FeCl3 Each Chlorine has a charge of (-1). 3 chlorines would have a charge of (-3). To balance the compound to a charge of zero, Fe must have a charge of (+3); Iron (III) Polyatomic ions are groups of atoms that travel together. Iron (III) Chloride

Examples with Type II Metal Ions: If there is one SO4 with a (-2) charge, the one Cu must have a (+2) to balance it CuSO4 VCl5 FeO Cu?+ SO42- Copper (II) Sulfate If there are five Cl’s with a (-1) charge each, the one V must have a (+5) to balance the (-5) from Chlorine V?+ Cl- Vanadium (V) Chloride If there is one O with a (-2) charge, the one Fe must have a (+2) to balance it. Fe?+ O2- Iron (II) Oxide