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Chapter Five Ionic & Covalent Compounds

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1 Chapter Five Ionic & Covalent Compounds

2 Section 5.1 Compounds

3 Revisiting Compounds Compound is composed of two or more elements combined in a specific ratio and held together by chemical bonds. Cannot be broken down by physical means.

4 Section 5.2 Lewis Dot Symbols

5 Why do atoms bond? Want to achieve stable electron configurations
Noble Gas configurations Valence electrons (outer electrons) are involved in bonding # of v.e. come from the group number Lewis Dot Symbols (or diagrams) show this

6 Lewis Dot Symbols/Diagrams
Draw the element symbol Represent v.e. with dots around the symbol 4 sides of the element symbol Start on top of symbol No more than 2 dots per side (max 8 for element) Do not double up electrons until each side has 1 v.e. Can be drawn for atoms or ions

7 Group Quiz #1 X Draw the Lewis Dot Diagrams for the following:
Silicon atom (Si) Bromide ion (Br-) What group of the periodic table does element X belong if its Lewis Dot Symbol was X

8 Section 5.3 Ionic Compounds & Bonding

9 Ionic Compounds Contain cations (positive ions) and anions (negative ions) Bonded together through ionic bonding: electrostatic attraction between oppositely charged particles Results from a transfer of electrons Ions cancel each other out producing a neutral compound

10 Transfer of Electrons Na Cl
With ionic bonds, electrons are TRANSFERRED Na Cl - +

11 Ionic Compounds & Structure
A chemical formula or just formula indicates the ratio of elements in a compound NaCl Li2O K3N Al2O3 Held together by a lattice work Individual compounds in a lattice work are called formula units.

12 Lattice Energy Lattice Energy is amount of energy required to convert a mole of an ionic solid to its constituent ions in the gas phase Ex: NaCl has a lattice energy of 788 kJ/mol It takes 788 kJ of energy to convert 1 mole of NaCl to 1 mole of Na+(g) and Cl-(g) The higher the lattice energy, the more stable the ionic compound is

13 Lattice Energy Examples

14 Factors that Affect Lattice Energy
Ionic Radius (distance between nuclei) Magnitude of Charges 1) Ionic Radius When distance between nuclei increases, attraction decreases, therefore weakening lattice energy

15 Factors that Affect Lattice Energy
Ionic Radius (distance between nuclei)

16 Factors that Affect Lattice Energy
2) Magnitude of Charges When distances are similar between nuclei, we must look at charges The higher the charge, the stronger the attraction, the stronger the lattice energy

17 Factors that Affect Lattice Energy
2) Magnitude of Charges

18 Section 5.4 Naming Ions & Ionic Compounds

19 Naming monatomic ions Also known as nomenclature Naming monatomic ions
Groups 1A, 2A, and 3A elements have charges equal to their group # (recall e- configs) Most anions from elements in groups 4A-7A have charges equal to their group # is 8 Ex: Oxygen Group 6 – 8 = -2

20 Charges you will need to know
P. 123

21 Naming monatomic ions Cations:
Named simply by putting the word ion to the name of the element Ex: K+ is the potassium ion, Al3+ is the aluminum ion Certain metals form more than one charge Ex: Fe2+ and Fe3+ Older system: Fe2+  Ferrous ion; Fe3+  Ferric ion Newer system: Fe2+  iron (II) ion; Fe3+  iron (III) ion

22 Naming monatomic ions Anions
Named by changing the element’s ending to –ide and adding the word ion Ex: Br- is the bromide ion; O2- is the oxide ion

23 Writing Formulas Cation and anion charges must equal ZERO
Use the criss-cross method to write formulas showing lowest whole number ratio Ex: Potassium Bromide, Zinc Iodide, Aluminum Oxide

24 Naming Ionic Compounds
Most ionic compounds are binary (only 2 elements: metal and nonmetal—in other words, cation & anion) Ionic compounds are named by using the cation name followed by the anion name, eliminating the words “ion” Ex: NaBr  Sodium Bromide CaF2 Calcium Fluoride Al2N3  Aluminum Nitride

25 Naming Ionic Compounds
What about ionic compounds with transition metals??? Use “reverse criss-cross” to determine original charge of cation (be sure anion has correct charge) Ex: FeCl2 Cr2S3 MnO

26 Group Quiz #2 If given the formula, write the name
If given the name, write the formula Ag+ sodium ion N3- zinc bromide K2O Strontium Carbide

27 Section 5.5 Covalent Bonding & Molecules

28 F F Covalent Bonding Bonding typically between two nonmetals
Electrons are shared; both atoms “feel” like they have a noble gas configuration F F

29 Molecules A neutral combination of at least 2 atoms in a specific arrangement held together by a chemical bond/force Can be an element (H2) or a compound (H2O)

30 Diatomic Molecules Molecules with only 2 atoms
Homonuclear: two of the same element H2, N2, O2, F2, Cl2, Br2, I2 HOFBrINCl Heteronuclear: two different elements CO, HCl, etc.

31 More with Molecules Allotrope: Elements with different distinct forms (ex: Carbon graphite & diamonds)

32 Different ways to represent molecules

33 Section 5.6 Naming Molecular Compounds

34 Traditional Naming

35 Traditional Naming Name the first element as is
Add the appropriate prefix to signify # of atoms Exclude mono for first element if there’s only one Name the second element with –ide ending Ex: N2P5 CS SO3

36 Writing the formulas Sulfur Tetrafluoride Tetraphosphorus Decasulfide
Tribromine Heptoxide

37 Exceptions Ex: SnCl4 and PbCl4
Can be named using ionic or covalent naming Tin (IV) Chloride or Tin Tetrachloride; Lead (IV) Chloride or Lead Tetrachloride

38 Exceptions: Hydrogen Compounds
B2H6 Diborane SiH4 Silane NH3 Ammonia PH3 Phosphine H2O Water H2S Hydrogen Sulfide *Responsible for knowing the one’s in red

39 Exceptions: Binary Acids
Acids typically have hydrogen at the beginning When dissolved in water, they typically produce hydrogen ions (H+) HCl in gas form is hydrogen chloride HCl dissolved in water is hydrochloric acid

40 Binary Acids How to name binary acids: Change “hydrogen” into “hydro-”
Take the root of the second element and add “-ic” to the ending. End with acid Ex: HBr(aq)

41 Name/Write these acids
Hydrofluoric acid H3N(aq) Hydrosulfuric acid H3P(aq)

42 Group Quiz #3 Name/Write the following: SF6 P2I4 Diboron Heptoxide
Hydroiodic acid H2Se(aq)

43 Section 5.7 Covalent Bonding in Ionic Species

44 Compounds with Polyatomic Ions
Polyatomic ions: ions that contain multiple atoms/elements (held together by covalent bonding) Act as a group; can be treated as one Name these compounds using the same rules as we did for ionic You must know table 5.10 in your text book!

45 List of Polyatomic Ions from Text
You are responsible for knowing the name, the formula, and the charge for each polyatomic ion in table 5.10 (this is a SHORTENED list!)

46 Writing Formulas Ammonium Chloride Cobalt (II) Nitrate Try These
Calcium Phosphate Manganese (III) Carbonate

47 Naming Formulas Name the following compounds: Fe2(SO4) Al(OH)3 NH4NO2

48 Oxoacids Acids that contain oxoanions (polyatomic ions with oxygen)
Ex: NO3- makes the oxoacid HNO3(aq) Ex: SO42- makes the oxoacid H2SO4(aq) Continue adding hydrogen (+1) to the beginning of the oxoanion until the net charge is ZERO Just like ionic rules

49 Naming Oxoacids Do NOT start with hydro-
START with the root of the polyatomic ion Add the appropriate suffix If the polyatomic ends in –ate, change to –ic If the polyatomic ends in –ite, change to –ous 4) Add the word “acid Example: H2CrO4 HNO2

50 Monoprotic vs. Polyprotic Acids
Monoprotic only has 1 ionizable hydrogen HNO3, HCl, HC2H3O2 Polyprotic has more than 1 ionizable hydrogen H2S, H3PO4 Ionization will happen in steps

51 Hydrates Compounds with specific number of water molecules within its solid structure Use greek prefixes to name water part CuSO4 * 5H2O Anhydrous salt is the compound w/o water Has distinct different properties than its hydrate form

52 Group Quiz #4 Name/Write the following Sulfurous Acid
Iron (II) Acetate NaOH H2CO3(aq) Strontium Nitrate Tetrahydrate

53 Section 5.8 Molecular and Formula Masses

54 Review! Determine the molecular mass of the following compounds:
Propane, C3H8 Lithium Hydroxide, LiOH

55 Section 5.9 Percent Composition of Compounds

56 Percent Composition Percent by mass of every element in a compound
Divide the mass of element by the mass of the entire compound Ex: What is the percent composition of H2O?

57 Section 5.10 Molar Mass

58 Review!

59 Empirical Formulas vs. Molecular Formulas
Molecular Formulas: The TRUE formula for a compound Shows exactly how many of each element is in a compound via subscripts Ex: C6H12O6, H2O Empirical Formulas: The lowest WHOLE number ratio of elements in a compound May or may not be the true formula Ex: CH2O, H2O

60 Figuring out an empirical and molecular formula from percentages
Ex: An unknown compound was found to have a percent composition as follows: 47.0 % potassium, 14.5 % carbon, and 38.5 % oxygen. What is its empirical formula? If the true molar mass of the compound is g/mol, what is its molecular formula?

61 Another Example Nitrogen and oxygen form an extensive series of oxides with the general formula NxOy. One of them is a blue solid that comes apart, reversibly, in the gas phase. It contains 36.84% N. What is the empirical formula of this oxide?

62 Group Quiz #5 Write the empirical formula for the following compounds.
C8H18 C2H6O2 A compound with an empirical formula of C4H4O and a molar mass of 136 grams per mole. What is the molecular formula of this compound?


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