Chapter 8: Ionic Compounds 11/16/15

Objectives Students will be able to Define chemical bond Related chemical bond formation to electron configuration Describe the formation of positive and negative ions

8.1: Forming Chemical Bonds Chemical bond- the force that holds two atoms together Form by the attraction btwn + nucleus and – e- + ion and a - ion Ionic bonds- exist between oppositely charged ions Cation- positively charged ion Anion- negatively charged ion

Mini-review Electron configuration reveals Principle Energy Level where valence electrons are found Valence electrons are the electrons involved in bonding Represent valence electrons via electron dot structures

Formation of Positive Ions Positive ions form when atoms lose electrons in order to attain 8 valence electrons (like a noble gas) Examples: Na 1s22s22p63s1  1 val. e- When sodium loses that one electron it assumes a noble gas config. of [He] 2s22p6 Once it ionizes it then has more protons than electrons and has a charge of +1. (CATIONS)

Formation of Negative Ions Again, atoms want to attain 8 val e- Example: Cl: 1s22s22p63s23p5 will gain 1 e- to attain a tot. of 8 When chlorine gains that one electron it assumes a noble gas config. of s2p6 Once it ionizes it then has more electrons than protons and has a charge of -1. (ANIONS)

Charge Chart – write on your periodic table…no need to copy word for word here. Group 1A  all will form +1 charge Group 2A  all will form +2 charge Group 3A  all will form +3 charge Group 4A  +/- 4 charge Group 5A  all will form a -3 charge Group 6A  all will form a -2 charge Group 7A  all will form a -1 charge Group 8A  will not form a charge

8.2 Formation of Ionic Bond Ionic bond- the electrostatic force that holds oppositely charged particles together Forms between positively charged metal cations and negatively charged non-metal anions. Example: Na+1 and Cl-1 becomes NaCl 1s22s22p63s1 3p53s2p62s21s2

Also explained via Electron Dot Models

Ionic Vocab. If a metal combines with a non-metal it forms an ionic compound called a salt. Exception: A metal bonding with oxygen is called an oxide. Many ionic compounds are binary which mean they consist of two elements.

What happens if…. A compound forms from Calcium (Grp. 2A) and Fluorine (Grp. 7A) Calcium will need to lose _2__ electrons to become stable. Fluorine will need to gain _1_ electron to become stable. SO, what happens? One Ca+2 cation will attract two F-1 anions CaF2

In-class Ex. page 217 7. Sodium and nitrogen 8. lithium and oxygen 9. strontium and fluorine 10. aluminum and sulfur 11. cesium and phosphorus

Properties of Ionic Compounds Crystalline structure Large amt. of energy required to break bonds Formation of ionic bonds is always exothermic

Solid state non-conductors (ions fixed) In aqueous solution  great conductors (aka electrolytes) (ions can move)

Energy During any chemical reaction (rxn) energy is either absorbed or released. Endothermic – when E is absorbed Exothermic – when E is released Formation of ionic compounds from + or – ions is ALWAYS exothermic

Lattice energy The energy required to separate one mole of the ions of an IC The strength of the forces holding ions in place is reflected by the lattice energy. The more – the lattice E, the stronger the force of attraction.

8.3 Names and formulas for ionic compounds 11-17-15

Bell Ringer – turn in Write the ionic compound equation for when the following elements form an ionic bond: Potassium and Iodide Magnesium and Chloride Aluminum and Bromide Cesium and Nitride Barium and Sulfide Magnesium and Carbon Rubidium and Oxygen

Objectives Students will be able to Write formulas for ionic compounds and oxyanions Name ionic compounds and oxyanions

8.3 Names and Formulas for Ionic Compounds Formula units simplest ratio of the ions represented in an ionic compound Overall charge (net charge) is ZERO Ex. KBr [one ion of potassium (K) and one ion of Bromine (Br)]

Determining Charge Monotomic ions: single element ions charge is equivalent to the group number (Group 1A-Group 4A) Charge is called its oxidation number Oxidation state equals the number of electrons transferred from an atom of the element to form the ion. Transition elements can have more than one oxidation state (see page 222, table 8.5)

Polyatomic Ions- ions made up of more than one element. The charge on polyatomic ions applies to the entire group of atoms Acts as an individual ion rather than a group Ex. NH4+1 and Cl-1 NH4Cl

Common Polyatomic Ions

Polyatomic Ions you will be responsible for memorizing Ammonium Nitrite Nitrate Hydroxide Hydrogen carbonate Chlorate Bromate Acetate Carbonate Sulfite Sulfate Peroxide phosphate

Naming Compounds With monotomic ions, cations stay the same; however, anions change their ending to –ide Polyatomic ions: Most are oxyanions (has oxygen) Some are composed of exact same ions but in different amounts The ion with more oxygen ends in -ate The ion with less oxygen ends in –ite Ex. NO3-1 nitrate NO2-1 nitrite

In-Class Ex. Page 225 24. Sodium and nitrate 25. Calcium and chlorate 26. Aluminum and carbonate 27. Potassium and chromate 28. Magnesium and carbonate

Chlorine (forms 4 oxyanions) ClO4-1: perchlorate ClO3-1:chlorate ClO2-1: chlorite ClO-1: hypochlorite

Rules in a Nutshell 1. Name cation before anion 2. Monotomic cations use the name 3. Monotomic anions use the root of the name and add –ide 4. Groups 1-2 metals have one oxidation number while transition metals have more than one 5. Polyatomic ions  name them.

Practice 8.3 on your worksheet packet

8.4 Metallic bonds and properties of metals 11-18-15 8.4 Metallic bonds and properties of metals

Bell Ringer – Turn in – 11/18/15 Name each of the following ionic compounds: K2O CaCl2 Mg3N2 NaClO KNO3 Give the formula for each of the following ionic compounds: Calcium iodide Silver (I) bromide Copper (II) chloride Beryllium hydroxide Magnesium phosphate

8.4 Metallic Bonds and Properties of Metals Objectives: Students will be able to Describe a metallic bond Explain the physical properties of metals in terms of metallic bonds Define and describe alloys

8.4 talks about when two or more metals combine. RECALL: IONIC BONDS Occur between metals (cation) and nonmetals (anion) Na (metal – cation) and Cl (nonmetal – anion) NEW: 8.4 talks about when two or more metals combine. METALLIC BONDS

METALLIC BONDS When metals bond together, they don’t do so ionically like metals and nonmetals. They create a sea of electrons Electron sea model E- move between all atoms – delocalized electrons

Very similar to a lattice structure Metallic cation is formed when their valence e- move away from them. Metallic bond is the attraction of metallic cations for delocalized e-.

Properties of Metals It requires more energy to boil a metal than to melt it b/c it has strong metallic bonds keeping atoms together

Properties of Metals Metals are malleable Hammered into sheets Drawn into wires Metallic bonds allow atoms to move past each other

Properties of Metals They’re durable Even though the e- move around between atoms, they’re not easily removed from the metal as a whole

Properties of Metals Metals are good conductors of electricity b/c of delocalized electrons move around.

Properties of Metals The more delocalized electrons that are free to move the harder/stronger the metallic bonds are. Alkali metals considered soft and not as strong b/c they have only 1 delocalized e- Transition metals like chromium, iron, and nickel have more delocalized e- and are harder and stronger

Metal Alloys Due to the nature of metallic bonds Easy to introduce other elements into a metallic crystal to make an ALLOY. Alloy – is a mixture of different elements that has metallic properties. Properties depend on which elements they contain. 2 types Substitutional – take out some of the atoms and fill with similar sized atoms Ex: sterling silver, brass, pewter, 10 carat gold Interstitial – small holes filled with smaller atoms (strengthens) Ex: carbon steel

Stainless steel (instruments, sinks, appliances)

Pewter (tableware)

Gold -10 carat (jewelry)

Dental amalgam (dental filings)

Cast iron (casting, cooking pans)

Bronze (bearings, bells, medals)

Brass (plumbing, hardware, lighting)

Alnico (magnets)

Lead shot (shotgun shells)

Practice Complete the 8.4 worksheet in your packet