Chapter 7. Ionic Compounds and Metals

Transcription

1 Chapter 7 Ionic Compounds and Metals

2 Periodic Trends Metals O Hate electrons O Give electrons away. O Have a low ionization energy. O Ions are always postive. O Cations (meow) Non-Metals O Love electrons O Take electrons from other elements O Have a high ionization energy O Ions are always negative. O Anions

3 Valence Electrons O Most important electrons in an element. O Electrons in the s and p orbitals O nsnp O n=principle energy level O s= s orbital electrons O p= the p orbital electrons O *****Every atom wants to obtain a s 2 p 6 configuration!!!!

4 Practice Practice Practice O Mg O Cl O O O I O K O S O Na O N

5 Lewis Dot Structure O Easy way to show an elements valence electrons. O Use dots to represent the valence electrons.

6 Lewis Dot Structure O Give the number of valence electrons and draw the Lewis Dot structures for the following elements: O C O F O Ca O Li O Mn O S O P

7 Octet Rule O Atoms gain, lose, or share electrons in order to achieve 8 valence electrons. O Every atom wants to be an noble gas- O s 2 p 6 O Metals lose electrons. O Non-metals gain electrons. O Identify weather elements gain or lose electrons. O K- O O- O S- O Fe- O P-

8 Octet Rule O Write the electron configuration. Determine if an element will lose or gain electrons and give its ionic form. O Aluminum O Chlorine O Nitrogen O Copper

9 Writing the EC for Ions

10 Octet Rule O Write the Lewis Dot Structure for these elements. O Al to Al 3+ O Cu to Cu 2+ O Cl to Cl - O F to F -

11 Ions O Elements that have lost or gained electrons to achieve an s 2 p 6. O Ionic Form: O Anion-negative, non-metal O Cation-positive, metal O Charge: O Depends on the number of electrons gained or lost. O Examples- O Na Na + O Lost 1 electron O Ba Ba 2+ O Lost 2 electrons O O O 2- O Gained two electrons

12 Ion Formation O Positive Ions- O Called cations O Lose electrons O Atoms get smaller O Lose an energy level O Metal Ions O Group 1-loses 1 e O Group 2-loses 2 e O Group 13 loses 3 e

13 Ion Formation O Positive Ions- O Transition Metals O Can lose 2 electrons O Colbalt II O Can also lose d orbital electrons. O Iron III O Electrons can be shifted to the d orbital O Copper I

14 Ion Formation O Negative Ions- O Called Anions O Add ide to the end of the anion O Chlorine=chloride O Oxygen=oxide O Get larger- O Electron repulse each other

15 Ion Formation O Negative Ions O Gain electrons to achieve s 2 p 6 O Non metal ions- O Group 15 = gains 3e - O Group 16 = gains 2e - O Group 17= gains 1e -

16 Ionic bonds and Compounds O Formation of Ionic bonds- O Two opposite charged ions attracted each other. O Cation-Anion O Ionic Bond- O Electrostatic force that holds opposite charged particles together

17 Ionic Bonds and Compounds O Ionic Compound- O Compounds that contain ionic bonds. O Metals + non-metals = ionic bond O Oxides and salts O Binary Ionic compounds- O Only two ions: cation+ anion O Sodium Chloride O Iron Oxide O Example: O Na + Cl O NaCl O Cr + O O Cr 2 O 3

18 Ionic Bonds and Compounds O Calcium and Fluorine- O O Calcium cation O Loses 2 electrons O 2+ charge Fluoride anion- O Gains 1 electron O 1- charge O Example- O The net charge of the compound must be 0 or neutral. O ***Electrons lost and gained must be equal***

19 Ionic Bonds and Compounds Compound Formation and Charge 1 Ca ion( Ca 2+ ion ) + 2 F ions 1- F ion ( ) =(1)(2+) +(2)(1-) = 0 Now, Try it for Lithium Oxide

20 Balancing Charges in Ionic O In any ionic compound Cation(s) charge must equal Anion(s) charge. O Ionic compound overall charge must = 0 O If Na=1+, then there must be an anion with a 1- charge. O If O=2-, then there must be a cation with a 2+ charge or 2 cation with a 1- charge. Compounds O Examples:

21 Easy Way-Yahoo! O Here is an easy way to do it: O An aluminum cation plus an oxide anion O Aluminum cation = 3+ O Oxide anion = 2- O Here we go- O Al 3+ + O 2- O Al 3+ + O 2- Al 2 O 3

22 Ionic Bonds and Compounds O Formation of Potassium ion and a Fluoride ion: O Formation of Barium ion and an Iodine ion: O Formation of a Copper (II) ion and a Nitrogen ion.

23 O Practice Sheet SEP

24 Ionic Bonds and Compounds O Properties of Ionic Compounds: O Physical: O Physical properties are different than the elements. O Ions are packed at a regular pattern that balance the different forces O Not a single unit of NaCl O Highly organized Sodium Chloride Crystal

25 Ionic Bonds and Compounds O Physical Properties- O Crystal lattice- O 3-D geometric arrangement of particles. O Positive ions surrounded by negative ions. O Negative ions surround by positive ions. O Hard, ridged, brittle O Can be broken when force is applied

26 Breaking the Ionic Bond

27 Ionic Bonds and Compounds O Physical Properties- O Ionic solid + water = individual ions O Electrolytes- O Aqueous solution of ions that conducts electricity. O Na +, Ca +, K +, Mg + O High melting points O High boiling points

28 Ionic Bonds and Compounds O Energy- O Endothermic O Energy is absorbed

29 Cold Packs

30 Ionic Bonds and Compounds O Energy- O Endothermic O Energy is absorbed O Exothermic O Energy is given off

31 Hand Warmers

32 Ionic Bonds and Compounds O Energy- O Endothermic O Energy is absorbed O Exothermic O Energy is given off O Formation of ionic bonds are exothermic.

33 O Lattice Energy- O Energy required to separate 1 mol of the ions of an ionic compound. O Shorter distance= greater the lattice energy. O The smaller the ion, the greater lattice energy.

34 O Lattice Energy- O Electrostatic charges increase as the ions get closer. O Energy increase as going from bottom to top. O The greater the charge on the ion, the greater lattice energy.

35 Lattice Energy

36 Practice-Lattice Energy O Use < or > to indicate which ionic compound has the greatest lattice energy. O LiCl KCl O NaBr NaCl O MgF 2 BaF 2 O SrS SrO O MgO RbF O LiF SrCl2

37 Names and Formulas for Ionic Compounds Its like naming a dog, easy but hard.

38 Oxidation Numbers O Oxidation Numbers (O.N.)- O Important so that we know whats going on is a reaction. O Number of electrons transferred from the atom to form an ion. O Na 1+ = O Ca 2+ = O N 3- = O S 2- = O Ag + = O Fe 3+ =

39 Naming Ionic Formula O Binary Ionic Formulas- O Two atoms O Cation always comes first O Anion is always second O Subscript =number of ions in the ionic compound.

40 Polyatomic Ions O Formulas for polyatomic ions- O Ions made of more than one atom. O Each exists as a unit. O Cannot be separated O NO 2- Nitrite O CN - Cyanide O O 2 2- Peroxide O Compounds for polyatomic ions- O NH 4 + O O 2 2-

41 Polyatomic Ions

42 Naming Ionic Compounds O Systematic Way- 1. Name the cation. 2. Ask the question, does it have more than one oxidative state? 1. If yes, add the roman numeral. 3. Name the anion. 4. If the compound has polyatomic ions, simply name the cation followed by the name of the polyatomic ion.

43 Problem Solving Strategy Determine the cation and anion for the given formula Does the cation have only one oxidation number? Write the name of the cation, Then write the name of the ion. Write the name of the cation, followed by a Roman numeral, next write the anion.

44 Follow the Steps to name the O Na 3 PO 4 O Name- O Fe O Name- O KOH O Name- O Ag 2 CrO 4 O Name- ionic compounds

45 O Write the formulas for the following ionic compounds- O Aluminum Hydroxide O Formula- O Barium Nitride O Formula O Potassium Sulfate O Formula O Sodium Carbonate O Formula-

46 Practice-Just Like This Guy!

47 Metallic Bonds and Properties of Metals

48 Metallic Bonds O Sea of electrons- O Metal cations combined with metal cations O Aluminum foil O How can these cations stick together? O Free floating electrons act as glue to keep the metal cations together.

49 Metallic Bonding

50 O Draw a lattice structure- Lattice Structure

51 Metallic Bonds O Delocalized electrons- O Electrons that don t belong to a specific atom. O Are free to move O Metallic Bond- O Attraction of metallic cations for delocalized electrons.

52 Properties of Metals O Melting and boiling points- O Vary greatly across the periodic table. O Moderately high melting point. O Cations and electrons are mobile moving past each other. O High boiling points=high energy input. O High attractive force among metallic bonds

53 Properties of Metals O Malleability, ductility, and durablity- O Malleability O Hammered into sheets O Ductile O Drawn into wire O Durable O Metallic cations are strongly attracted to the electrons that surround them.

54 Properties of Metals O Thermal and electrical conductivity- O Movement of mobile electrons around positive cations make metals good conductors of heat and electricty.

55 Properties of Metals O Hardness and Strength- O s electrons and d electrons are mobile O Addition of delocalized electrons makes metals harder. O Alkali metals are soft because they only have 1 delocalized electron-ns 1.

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57 Metal Alloys O Alloy- O Mixture of elements that have metallic properties. O Alloys are stronger. O Fe + another element = steel O Bronze O Sterling silver

58 Metal Alloys O Steel-Iron + carbon or chromium or vanadium O 24 Carat Gold- 100% Pure gold O 18 Carat Gold-75% Gold + Palladium + silver +copper O 14 Carat Gold- 58.3% Gold + other metals

59 Metal Alloys Common Name Composition Uses Brass Cu 67-90% Zn 10-33% Plumbing Gold, 10 carat Au 42%, Ag 12%, Cu % Jewerly Stainless Steel Fe 79%, Cr 14%, Ni 7% Instruments Sterling silver Ag 92.5%, Cu 7.5% Tableware Bronze Cu-70-95%, Zn 1-25%, Sn 1-18% Bells, medals