LecturePLUS Timberlake1 ChemIH: Chapters 8 & 9 Covalent Bonding Def: bonds btwn 2 nonmetals Nonmetals have high EN values so electrons must be shared Compounds w/covalent bonds are called molecular compounds.

Covalent Bonding single bond shares 1 pair electrons- ex:H 2 double bond shares 2 pairs electron-ex:O 2 triple bond shares 3 pairs electrons-ex: N 2 LecturePLUS Timberlake2

3 Covalent Bonding By sharing e-s, atoms obtain NGC, which makes them more stable than they were by themselves. H  +  H H : H = H  H = H 2 hydrogen molecule

LecturePLUS Timberlake4 Learning Check Indicate whether a bond between the following would be (I) Ionic OR (C) covalent ____A. sodium & oxygen ____B. nitrogen & oxygen ____C. phosphorus & chlorine ____D. calcium & sulfur ____E. chlorine & bromine

LecturePLUS Timberlake5 Solution Indicate whether a bond between the following would be (I) Ionic OR (C) covalent IA. sodium and oxygen CB. nitrogen and oxygen CC. phosphorus and chlorine ID. calcium and sulfur CE. chlorine and bromine

There are 3 types of molecular substances we will learn about. LecturePLUS Timberlake6

7 1. Diatomic Elements Elements that exist as atom pairs : H 2, O 2, N 2, Cl 2, Br 2, I 2, F 2, They are given the name of the element. octets          N  +  N   N ::: N   triple bond

LecturePLUS Timberlake8 Learning Check Use the name of the element to name a diatomic molecules. H 2 hydrogen N 2 nitrogen Cl 2 _______________ O 2 _______________ I 2 _______________

LecturePLUS Timberlake9 Solution Use the name of the element to name the following diatomic molecules. H 2 hydrogen N 2 nitrogen Cl 2 chlorine O 2 oxygen I 2 iodine

LecturePLUS Timberlake10 2. Binary Covalent Compounds Two nonmetals (def of binary covalent) 1. Name each element 2. End the last element in -ide 3. Add prefixes to show how many atoms of each (except when there’s only 1 atom of the 1 st element listed)

PREFIXES mono-1 penta-5 di-2hexa-6 tri-3hepta-7 tetra-4octa-8 LecturePLUS Timberlake11

LecturePLUS Timberlake12 Learning Check Fill in the blanks to complete the following names of covalent compounds. CO carbon ______oxide CO 2 carbon _______________ PCl 3 phosphorus _______chloride CCl 4 carbon ________chloride N 2 O_____nitrogen _____oxide

LecturePLUS Timberlake13 Solution CO carbon monoxide CO 2 carbon dioxide PCl 3 phosphorus trichloride CCl 4 carbon tetrachloride N 2 Odinitrogen monoxide

LecturePLUS Timberlake14 Learning Check A.P 2 O 5 1) phosphorus oxide 2) phosphorus pentoxide 3) diphosphorus pentoxide B.Cl 2 O 7 1) dichlorine heptoxide 2) dichlorine oxide 3) chlorine heptoxide C. Cl 2 1) chlorine 2) dichlorine 3) dichloride

LecturePLUS Timberlake15 Solution A.P 2 O 5 3) diphosphorus pentoxide B.Cl 2 O 7 1) dichlorine heptoxide C. Cl 2 1) chlorine

3. Organic Compounds Def: organic compounds contain carbon atoms hooked together. (Why do you think this element can hook up with many other atoms, including itself?)

Hydrocarbons-A Type of Organic Compound Def: hydrocarbons are made of hydrogen & carbon They are named by the number of carbon atoms a molecule contains. They are important as fuels.

Hydrocarbons The table below lists only hydrocarbons w/single bonds\ The names all end w/ “ane” CH 4 methaneC 6 H 14 hexane C 2 H 6 ethaneC 7 H 16 heptane C 3 H 8 propaneC 8 H 18 octane C 4 H 10 butaneC 9 H 20 nonane C 5 H 12 pentaneC 10 H 22 decane

Writing Formulas for Molecular Compounds 1.Analyze the name of the compound 2. Identify the type of compound (diatomic? binary? hydrocarbon?) 3. Reverse the process used to name it so you can determine the formula. (For binary, prefixes indicate the subscript.) LecturePLUS Timberlake19

Common v. Formal Names Formal Names follow the rules we have learned for naming compounds. Common Names are ones that don’t follow these rules. –Ex: water=

Frequently Used Common Names Water = H 2 O Ammonia = NH 3

MOLECULE Def: unit formed when elements combine via covalent bonding LecturePLUS Timberlake22

LecturePLUS Timberlake23 Covalent Bonds in NH 3 Bonding pairs H  H : N : H  Lone pair of electrons

Allotropes Def: molecules of the same element that differ in structure Ex 1: Carbon…graphite, charcoal, Buckminsterfullerine (“bucky ball”)= C 64 Ex 2: O 2 (oxygen) and O 3 (ozone)

Q:Why do we have to specify the number of atoms of each element in a covalent compound? A: Atoms of the same elements can combine in different ratios. Ex: C & O CO CO 2

Writing Formulas for Covalent Compounds 1. Identify it as a covalent: containing only nonmetals. 2. Determine what type of covalent it is: diatomic elementbinary hydrocarbon (ends in –ane)acid/base 3. Reverse the naming process. LecturePLUS Timberlake26

STOP HERE!!! LecturePLUS Timberlake27

Naming Ionic Compounds Binary Ionic Ionic Compounds contain- ing Polyatomic Ions. Ionic Cpds containing Transition Metals LecturePLUS Timberlake28

PLEASE NOTE: IF YOU ARE UNABLE TO IDENTIFY IONIC & COVALENT COMPOUNDS, YOU WILL BE LOST!!! PLEASE SEE ME IMMEDIATELY TO GET CAUGHT UP. LecturePLUS Timberlake29

LecturePLUS Timberlake30 Ionic Bonding & Electronegativity Nonmetals have high EN’s. Metals have low EN’s. Bonds between a metal & a nonmetal involve transfers of e-s b/c of the big difference in EN!

Binary Ionic Compounds Binary= 2 elements Ionic= 1 metal & 1 nonmetal LecturePLUS Timberlake31

Naming Binary Ionic Compounds 1. Identify & name the 2 elements in the compound. 2. Name the cation, which is the given the name of the element. 3. Name the anion, which is given the name of the element, w/the ending changed to “–ide.” LecturePLUS Timberlake32

PRACTICE Naming Binary Ionic Compounds 1. Na║Cl 2. Na = “sodium” 3. Cl = “chloride” (full name is “sodium chloride”) LecturePLUS Timberlake33

PRACTICE Naming Binary Ionic Compounds 1. Li 2 O 2 & 3. ____║____= ______ ______ ( cation (anion (cation name) (anion name) symbol) symbol) LecturePLUS Timberlake34

MORE PRACTICE Naming Binary Ionic Compounds-p __ of I.N. 1.KF 2.CaF 2 3.Al 2 O 3 LecturePLUS Timberlake35

Naming Ionic Compounds w/ Polyatomic Ions DEF: Charged particles containing more than 1 type of atom. Ex: SO 4 2- LecturePLUS Timberlake36

Naming Ionic Compounds w/ Polyatomic Ions 1.Identify the cation & the anion. (Draw a line between the 2 ions) 2.Name the cation, then the anion (find polyatomics on Table 5.3, p 159 of text). That’s it! LecturePLUS Timberlake37

PRACTICE :Naming Ionic Compounds w/ Polyatomic Ions EX: Na 2 SO 4 ____║____= ______ ______ ( cation (anion (cation name) (anion name) symbol) symbol) LecturePLUS Timberlake38

Naming Ionic Compounds w/ Polyatomic Ions Most polyatomic ions are anions. LecturePLUS Timberlake39

A Couple of Important Exceptions w/Polyatomic Ions Important Exception #1: there are 2 cations that contain NO METALS: NH 4 + (ammonium) H 3 O + (hydronium) (this can be tricky b/c we have always identified ionic compounds because they start with a metal cation.) LecturePLUS Timberlake40

A Couple of Important Exceptions w/Polyatomic Ions Important Exception #2: Some anions contain metals. Ex: MnO 4 - = permanganate Cr 2 O 7 2- = dichromate (this can be tricky b/c anions are usually a nonmetal) LecturePLUS Timberlake41

Copy Table 5.2 into Notes LecturePLUS Timberlake42

Naming Ionic Cpds Containing Transition Metals Ex: NiO 2 1.Determine the total # of negative charges in a unit of the compound: Ex: O 2- & O 2- = 4 total - charges 2. Determine the charge on the cation that will give you 4 total + charges Ex: Ni Write the cation & anion names. Write cation with the oxidation # written as a Roman numeral in parentheses: Ex: nickel (IV) oxide LecturePLUS Timberlake43

Writing Formulas for Binary Ionic Compounds 1. Identify the ionic charge (“oxidation number”) on the cation & anion. LecturePLUS Timberlake44

Writing Formulas for Binary Ionic Compounds ELEMENTOXIDATION # Group 11+ Group 22+ Group 133+ Group 144+ or 4- Group 153- Group 162- Group 171- LecturePLUS Timberlake45

Practice Predicting Oxidation #s Li O Mg F B LecturePLUS Timberlake46

Writing Formulas for Binary Ionic Compounds 2. A compound has NO CHARGE on it, so a formula unit (the smallest ratio of cations to anions) must have equal numbers of + & - charges. (use the LCM) LecturePLUS Timberlake47

Cross-Over Method You can use this to write formulas. Take the charge on the cation and use it as the subscript on the anion Take the charge on the anion and use it as the subscript on the cation Reduce the subscripts, if necessary LecturePLUS Timberlake48

Using the LCM to Write Ionic Formulas Ex: Li & F Ex: Li & O Ex: Al & O LecturePLUS Timberlake49

ANSWERS LiF Li 2 O Al 2 O 3 LecturePLUS Timberlake50

Writing Formulas for I.Cpds Containing Polyatomic Ions Determine the cation & anion Determine the oxidation # on each ion. (oxidation #s for polyatomics are found on Table 5.2) Write a balanced formula –If there is more than 1 of an ion, use parentheses, then a subscript LecturePLUS Timberlake51

Writing Formulas for I.Cpds Containing Polyatomic Ions Ex: see Practice Problems, p Write the formula for the compound formed from the following pairs of ions a) ammonium & sulfite ions IONS: NH 4 + & SO 3 2- NH 4 + FORMULA: (NH 4 ) 2 SO 3 LecturePLUS Timberlake52

Practice Problems, cont. from p 16 2of text 3b) 3c) 3d) 4a) 4b) 4c) 4d) LecturePLUS Timberlake53

Transition Metals QUESTION: What was strange about the e- configurations of transition metals? LecturePLUS Timberlake54 ANSWER: Their d sublevels overlap with the other sublevels in the next higher main E.L.

Oxidation #s of Transition Metals The d sublevel e-s are so close to the actual valence e-s, they sometimes act like valence e-s! See Table 5.4 on p 164 of text: Common Ions of Select Transition Metals Ex: Fe 2+ & Fe 3+ Write the e- configuration LecturePLUS Timberlake55

e- Configuration for Fe Fe=26 e-s 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 6 Valence e-s=4s 2 BUT, some 3d e-s can be lost too! NOTE: Students found this a bit confusing, or at best minimally helpful. Explain, but do not belabor the e- config. LecturePLUS Timberlake56

Writing Formulas for Ionic Cpds containing Transition Metals 1. Identify the cation & anion 2. Determine the oxidation #s on the cation & anion –The oxidation # of the cation is given in the name ex: Nickel (IV) = Ni 4+ –The Roman numeral is the oxidation# 3. Write a formula w/ 0 charge. LecturePLUS Timberlake57

Distillation Def: process of separating ionic & covalent compounds by heating them till the covalent compound evaporates. –The ionic compound remains in the flask –The covalent compound can be cooled & collected in a separate container. –This process is called distillation

LecturePLUS Timberlake59 Learning Check Match each set with the correct name: A. Na 2 CO 3 1) magnesium sulfite MgSO 3 2) magnesium sulfate MgSO 4 3) sodium carbonate B.Ca(HCO 3 ) 2 1) calcium carbonate CaCO 3 2) calcium phosphate Ca 3 (PO 4 ) 2 3) calcium bicarbonate

LecturePLUS Timberlake60 Solution A. Na 2 CO 3 3) sodium carbonate MgSO 3 1) magnesium sulfite MgSO 4 2) magnesium sulfate B.Ca(HCO 3 ) 2 3) calcium bicarbonate CaCO 3 1) calcium carbonate Ca 3 (PO 4 ) 2 2) calcium phosphate

LecturePLUS Timberlake61 Learning Check A. aluminum nitrate 1) AlNO 3 2) Al(NO) 3 3) Al(NO 3 ) 3 B. copper(II) nitrate 1) CuNO 3 2) Cu(NO 3 ) 2 3) Cu 2 (NO 3 ) C. Iron (III) hydroxide 1) FeOH2) Fe 3 OH3) Fe(OH) 3 D. Tin(IV) hydroxide 1) Sn(OH) 4 2) Sn(OH) 2 3) Sn 4 (OH)

LecturePLUS Timberlake62 Solution A. aluminum nitrate 3) Al(NO 3 ) 3 B. copper(II) nitrate 2) Cu(NO 3 ) 2 C. Iron (III) hydroxide 3) Fe(OH) 3 D. Tin(IV) hydroxide 1) Sn(OH) 4