Chapter 5 Nomenclature Chemical BONDING Chemical Bond A

Chapter 5 Nomenclature

Chemical BONDING

Chemical Bond • A bond results from the attraction of nuclei for electrons – All atoms trying to achieve a stable octet • IN OTHER WORDS – the p+ in one nucleus are attracted to the e- of another atom • Electronegativity

• Molecule: 2 or more atoms joined by a chemical bond • Compound: a molecule composed of atoms of 2 or more different elements bonded together in a fixed ratio

Diatomic Molecule • Diatomic Molecule: a molecule containing 2 atoms • The Diatomic molecules are: • Hydrogen (H 2) Nitrogen (N 2) Oxygen (O 2) Fluorine (F 2) Chlorine (Cl 2) Iodine (I 2) Bromine (Br 2)

• Chemical formula: represents the relative numbers of atoms of each kind in a chemical compound by using atomic symbols and numeric subscripts • Bond energy: the energy required to break a chemical bond and form neutral atoms

Naming Compounds Types of Chemical Bonds: (4) 1. 2. 3. 4. Ionic bonds Covalent

Bond Formation • exothermic process E N E R G Y Reactants Energy released Products

Breaking Bonds • Endothermic reaction – energy must be put into the bond in order to break it E N E R G Y Reactants Products Energy Absorbed

Bond Strength • Strong, STABLE bonds require lots of energy to be formed or broken • weak bonds require little E

Two Major Types of Bonding • Ionic Bonding – forms ionic compounds – transfer of e- • Covalent Bonding – forms molecules – sharing e-

Naming Compounds Return to TOC

One minor type of bonding • Metallic bonding – Occurs between like atoms of a metal in the free state – Valence e- are mobile (move freely among all metal atoms) – Positive ions in a sea of electrons • Metallic characteristics – High mp temps, ductile, malleable, shiny – Hard substances – Good conductors of heat and electricity as (s) and (l)

It’s the mobile electrons that enable me tals to conduct electricity!!!!!!

IONic Bonding • electrons are transferred between valence shells of atoms • ionic compounds are NOT MOLECULES made of ions • ionic compounds are called Salts or Crystals

IONic bonding • Always formed between metals and non-metals + [METALS ] [NON-METALS ] Lost e- Gained e-

Properties of Ionic Compounds SALTS Crystals • hard solid @ 22 o. C • high mp temperatures • nonconductors of electricity in solid phase • good conductors in liquid phase or dissolved in water (aq)

Covalent Bonding molecules • Pairs of e- are shared between non-metal atoms • electronegativity difference < 2. 0 • forms polyatomic ions

Properties of Molecular Substances Covalent bonding • Low m. p. temp and b. p. temps • relatively soft solids as compared to ionic compounds • nonconductors of electricity in any phase

Covalent, Ionic, metallic bonding? • NO 2 • sodium hydride • Hg • H 2 S • sulfate • NH 4+ • CO • Aluminum • Co phosphate • KH Can You Tell • KCl What type of • HF bond is formed

Drawing ionic compounds using Lewis Dot Structures • Symbol represents the KERNEL of the atom (nucleus and inner e-) • dots represent valence e-

Na. Cl • This is the finished Lewis Dot Structure How did we get here? + [Na] [ Cl ] -

• Step 1 after checking that it is IONIC – Determine which atom will be the +ion – Determine which atom will be the - ion • Step 2 – Write the symbol for the + ion first. • NO DOTS – Draw the e- dot diagram for the – ion • COMPLETE outer shell • Step 3 – Enclose both in brackets and show each charge

Draw the Lewis Diagrams • Li. F • Mg. O • Ca. Cl 2 • K 2 S

Drawing molecules using Lewis Dot Structures • Symbol represents the KERNEL of the atom (nucleus and inner e-) • dots represent valence e-

Always remember atoms are trying to complete their outer shell! The number of electrons the atoms needs is the total number of bonds they can make. Ex. … H? O? F? N? Cl? C? one two one three one four

Methane CH 4 • This is the finished Lewis dot structure How did we get here?

• Step 1 – count total valence e- involved • Step 2 – connect the central atom (usually the first in the formula) to the others with single bonds • Step 3 – complete valence shells of outer atoms • Step 4 – add any extra e- to central atom IF the central atom has 8 valence e- surrounding it. . YOU’RE DONE!

Sometimes. . . • You only have two atoms, so there is no central atom, but follow the same rules. • Check & Share to make sure all the atoms are “happy”. Cl 2 Br 2 H 2 O 2 N 2 HCl

• DOUBLE bond – atoms that share two e- pairs (4 e-) O O • TRIPLE bond – atoms that share three e- pairs (6 e-) N N

Draw Lewis Dot Structures You may represent valence electrons from different atoms with the following symbols x, , CO 2 NH 3

Draw the Lewis Dot Diagram for polyatomic ions • Count all valence e- needed for covalent bonding • Add or subtract other electrons based on the charge REMEMBER! A positive charge means it LOST electrons!!!!!

Draw Polyatomics • Ammonium • Sulfate

Types of Covalent Bonds • NON-Polar bonds – Electrons shared evenly in the bond – E-neg difference is zero Between identical atoms Diatomic molecules

Types of Covalent Bonds Polar bond – Electrons unevenly shared

non-polar MOLECULES • Sometimes the bonds within a molecule are polar and yet the molecule is non-polar because its shape is symmetrical. H Draw Lewis dot first and see if equal on all sides H C H H

Polar molecules (a. k. a. Dipoles) • Not equal on all sides – Polar bond between 2 atoms makes a polar molecule – asymmetrical shape of molecule

+ H Cl

Water is asymmetrical + O - H + H

Water is a bent molecule H H O H H

W-A-T-E-R as bent as it can be! Water’s polar MOLECULE! The H is positive The O is not - not

Making sense of the polar non-polar thing BONDS Non-polar Polar Identical Different MOLECULES Non-polar Symmetrical Polar Asymmetrical

IONIC bonds …. Ionic bonds are so polar that the electrons are not shared but transferred between atoms forming ions!!!!!!

4 Shapes of molecules

Linear (straight line) Ball and stick model Space filling model

Bent Ball and stick model Space filling model

Trigonal pyramid Ball and stick model Space filling model

Tetrahedral Ball and stick model Space filling model

Intermolecular attractions • Attractions between molecules – van der Waals forces • Weak attractive forces between non -polar molecules – Hydrogen “bonding” • Strong attraction between special polar molecules

van der Waals • Non-polar molecules can exist in liquid and solid phases because van der Waals forces keep the molecules attracted to each other • Exist between CO 2, CH 4, CCl 4, CF 4, diatomics and monoatomics

van der Waals periodicity • increase with molecular mass. – Greater van der Waals force? • F 2 Cl 2 Br 2 I 2 • increase with closer distance between molecules – Decreases when particles are farther away

Hydrogen “Bonding” • Strong polar attraction – Like magnets • Occurs ONLY between H of one molecule and N, O, F of another H “bond”

Why does H “bonding” occur? • Nitrogen, Oxygen and Fluorine – small atoms with strong nuclear charges • powerful atoms – very high electronegativities

Intermolecular forces dictate chemical properties • Strong intermolecular forces cause high b. p. , m. p. and slow evaporation (low vapor pressure) of a substance.

Which substance has the highest boiling point? • HF • NH 3 • H 2 O Fluorine has the highest e-neg, SO HF will experience the • WHY? needs the most energy to weaken the i. m. f. and boil strongest H bonding and

Density? ?

H 2 O(s) is less dense than H 2 O(l) • The hydrogen bonding in water(l) molecules is random. The molecules are closely packed. • The hydrogen bonding in water(s) molecules has a specific open lattice pattern. The molecules are farther apart.

Naming Compounds Chemical Names and formulas • With all of the compounds and all of the elements to be identified, a systematic method for writing formulas and naming compounds is necessary • A correctly written chemical formula must represent the known facts about the composition of a compound • Care must be taken so that subscripts are correct Return to TOC Copyright © Cengage Learning. All rights reserved 67

Naming Compounds Using Chemical formulas • Chemical formulas indicate the elements present in a compound and the relative numbers of atoms of each element in the compound • In chemical formulas, the elements are given by their symbols and the relative number of atoms of each element by numerical subscript • Ex H 2 SO 4 the H, S & O are symbols, the 2 & 4 are subscripts Return to TOC Copyright © Cengage Learning. All rights reserved 68

Naming Compounds Return to TOC

• Ion: A charged particle due to loss or gain of electrons • Cation: positive charge ion represented by a (+) after the chemical symbol (metal) Ex Na+ • Anion: negative charge ion represented by a (-) after the chemical symbol (metal) Ex Cl-

Naming Compounds Monatomic Ions • Positive ions are named by the element name followed by the word “ion” • Examples : • K+ potassium ion magnesium ion Mg+2 aluminum ion • Al+3 Return to TOC Copyright © Cengage Learning. All rights reserved 72

Naming Compounds • Negative ions are named by dropping the ending of the element name and adding the ending “ide” to it followed by the word “ion” • • Examples: FS-2 I- fluoride ion sulfide ion Iodide ion Return to TOC Copyright © Cengage Learning. All rights reserved 73

Naming Compounds Learning Check Give the names of the following ions: Ba 2+ _____ Al 3+ _____ K+ _____ N 3 _____ O 2 _____ F _____ P 3 _____ S 2 _____ Cl _____ 74 Return to TOC

Naming Compounds Solution Ba 2+ barium Al 3+ aluminum K+ potassium N 3 nitride O 2 oxide F fluoride P 3 phosphide S 2 sulfide Cl chloride 75 Return to TOC

Naming Compounds • Binary Compounds § • Binary Ionic Compounds § • Composed of two elements Metal—nonmetal Binary Covalent Compounds § Nonmetal—nonmetal Return to TOC Copyright © Cengage Learning. All rights reserved 76

Naming Compounds Binary Ionic Compounds Return to TOC Copyright © Cengage Learning. All rights

Naming Compounds • Binary ionic compounds contain positive cations and negative anions. § Type I compounds • § Metal present forms only one cation. Type II compounds • Metal present can form 2 or more cations with different charges. Return to TOC Copyright © Cengage Learning. All rights reserved 78

Naming Compounds Type I Compounds Metals (Groups I, II, and III) and Non-Metals Metal _____ Sodium + Non-Metal _____ide Chlorine Sodium Chloride Na. Cl Return to TOC 79

Naming Compounds Common Simple Cations and Anions Return to TOC Copyright © Cengage Learning.

Naming Compounds Rules for Naming Type I Ionic Compounds 1. The cation is always named first and the anion second. 2. A simple cation takes its name from the name of the element. 3. A simple anion is named by taking the first part of the element name (the root) and adding –ide. Return to TOC Copyright © Cengage Learning. All rights reserved 81

Naming Compounds Binary Ionic Compounds (Type I) • Examples: KCl Potassium chloride Mg. Br

Naming Compounds Exercise What is the name of the compound Sr. Br 2? a) b) c) d) strontium bromine sulfur bromide strontium dibromide strontium bromide Return to TOC Copyright © Cengage Learning. All rights reserved 83

Naming Compounds • Strontium bromide. Sr is the symbol for strontium. • Br is the symbol for bromine, • take the first part of the element name (the root) and add –ide to get the name bromide. Return to TOC Copyright © Cengage Learning. All rights reserved 84

Naming Compounds Binary Ionic Compounds (Type II) • • Metals in these compounds can form more than one type of positive charge. Charge on the metal ion must be specified. Roman numeral indicates the charge of the metal cation. Transition metal cations usually require a Roman numeral. Return to TOC Copyright © Cengage Learning. All rights reserved 85

Naming Compounds Type II Compounds Metals (Transition Metals) and Non-Metals Iron +Roman Numeral (__) III + Non-Metal ____ide Bromine Metal ______ Iron (III) Bromide Fe. Br 3 Compare with Iron (II) Bromide Fe. Br 2 Metals (Transition Metals) and Non-Metals Older System Metal (Latin) _______ Ferrous + ous or ic + Non-Metal ____ide Bromine Ferrous Bromide Fe. Br 2 Compare with Ferric Bromide Fe. Br 3 Return to TOC 86

Naming Compounds Different names are needed for positive ions of 2 different charges formed by the same metal • Old system: “ous” ending for lower charge • “ic” ending for higher charge • New system: gives actual charge on the ion as a roman numeral Return to TOC Copyright © Cengage Learning. All rights reserved 87

Naming Compounds Common Type II Cations Return to TOC Copyright © Cengage Learning. All

Naming Compounds Rules for Naming Type II Ionic Compounds 1. The cation is always named first and the anion second. 2. Because the cation can assume more than one charge, the charge is specified by a Roman numeral in parentheses. Return to TOC Copyright © Cengage Learning. All rights reserved 89

Naming Compounds Binary Ionic Compounds (Type II) • Examples: Cu. Br Copper(I) bromide Fe.

Naming Compounds Exercise What is the name of the compound Cr. O 2? a) b) c) d) chromium oxide chromium(II) oxide chromium(IV) oxide chromium dioxide Return to TOC Copyright © Cengage Learning. All rights reserved 91

Naming Compounds • Chromium(IV) oxide. Cr is the symbol for chromium. O is the symbol for oxygen, but • take the first part of the element name (the root) and add –ide to get the name oxide. • Since chromium can have more than one charge, a Roman numeral must be used to identify that charge. • There are two oxygen ions each with a 2– charge, giving an overall charge of – 4. • Therefore, the charge on chromium must be +4. Return to TOC Copyright © Cengage Learning. All rights reserved 92

Naming Compounds Exercise What is the correct name of the compound that results from the most stable ion for sulfur and the metal ion that contains 24 electrons? a) b) c) d) iron(III) sulfide chromium(II) sulfide nickel(III) sulfate iron(II) sulfide Return to TOC Copyright © Cengage Learning. All rights reserved 93

Naming Compounds • Iron(II) sulfide. • For sulfur, take the first part of the element name (the root) and add –ide to get the name sulfide. • Iron with a +2 charge (as the Roman numeral indicates) contains 24 electrons (26 p – 24 e = +2 charge). Return to TOC Copyright © Cengage Learning. All rights reserved 94

Naming Compounds Binary Covalent Compounds Return to TOC Copyright © Cengage Learning. All rights

Naming Compounds Rules for Naming Type III Binary Compounds • Formed between two nonmetals. 1. The first element in the formula is named first, and the full element name is used. 2. The second element is named as though it were an anion. 3. Prefixes are used to denote the numbers of atoms present. 4. The prefix mono- is never used for naming the first element. Return to TOC Copyright © Cengage Learning. All rights reserved 96

Naming Compounds Type III Compounds Non-Metals and Non-Metals Use Prefixes such as mono, di, tri, tetra, penta, hexa, hepta, etc. CO 2 Carbon dioxide CO Carbon monoxide PCl 3 Phosphorus trichloride CCl 4 Carbon tetrachloride N 2 O 5 Dinitrogen pentoxide CS 2 Carbon disulfide Return to TOC Copyright © Cengage Learning. All rights reserved 97

Naming Compounds Prefixes Used to Indicate Numbers in Chemical Names Additional Prefixes 9 nona- 10 deca- 11 undeca- 12 dodeca- 13 trideca- 14 tetradeca- 15 pentadeca- 16 hexadeca- 17 heptadeca- 18 octadeca- 19 nonadeca- 20 icosa Return to TOC Copyright © Cengage Learning. All rights reserved 98

Naming Compounds Binary Covalent Compounds (Type III) • Examples: CO 2 Carbon dioxide SF 6 Sulfur hexafluoride N 2 O 4 Dinitrogen tetroxide Return to TOC Copyright © Cengage Learning. All rights reserved 99

Naming Compounds Exercise What is the name of the compound Se. O 2? a) b) c) d) selenium oxide selenium dioxide selenium(II) oxide selenium(IV) dioxide Return to TOC Copyright © Cengage Learning. All rights reserved 100

Naming Compounds • • Selenium dioxide. Se is the symbol for selenium. O is the symbol for oxygen, take the first part of the element name (the root) and add –ide to get the name oxide. • Since they are both nonmetals, prefixes are used to identify the elements (except mono- is not used for the first element). • Two oxygen atoms require the use of the prefix di-, making the name dioxide. Return to TOC Copyright © Cengage Learning. All rights reserved 101

Naming Compounds Flow Chart for Naming Binary Compounds Return to TOC Copyright © Cengage

Let’s Practice! Naming Compounds Name the following. Ca. F 2 K 2 S Co. I 2 Sn. F 4 OF 2 Cu. I SO 2 Sr. S Li. Br Calcium Flouride Potassium Sulfide Cobalt (II) Iodide or Cobaltous Iodide Tin (II) Fluoride or Stannous Fluoride Tin (IV) Fluoride or Stannic Fluoride Oxygen diflouride Copper (II) Iodide or Cupric Iodide Copper (I) Iodide or Cuprous Iodide Sulfur dioxide Strontium Sulfide Lithium Bromide Return to TOC 103

Naming Compounds Naming Polyatomic compounds Return to TOC Copyright © Cengage Learning. All rights

Naming Compounds • • Polyatomic ions are charged entities composed of several atoms bound together. They have special names and must be memorized. We will be using our Fat Daddy Chart to help us with naming the polyatomic compounds Those used often enough will be memorized just out of sheer practice Return to TOC Copyright © Cengage Learning. All rights reserved 105

Naming Compounds Names of Common Polyatomic Ions (page 130) Return to TOC Copyright ©

Naming Compounds • Naming ionic compounds containing polyatomic ions follows rules similar to those for binary compounds. § Ammonium acetate Return to TOC Copyright © Cengage Learning. All rights reserved 107

Naming Compounds Examples Na. OH Sodium hydroxide Mg(NO 3)2 Magnesium nitrate (NH 4)2 SO 4 Ammonium sulfate Fe. PO 4 Iron(III) phosphate Return to TOC Copyright © Cengage Learning. All rights reserved 108

Naming Compounds Learning Check Select the correct name for each. A. Fe 2 S 3 1) iron sulfide 2) iron(II) sulfide 3) iron(III) sulfide B. Cu. O 1) copper oxide 2) copper(I) oxide 3) copper(II) oxide 109 Return to TOC

Naming Compounds Solution Select the correct name for each. A. Fe 2 S 3 3) iron(III) sulfide Fe 3+ S 2– B. Cu. O 3) copper(II) oxide Cu 2+ O 2– 110 Return to TOC

Naming Compounds Overall Strategy for Naming Chemical Compounds Return to TOC Copyright © Cengage

Naming Compounds Exercise What is the name of the compound KCl. O 3? a) b) c) d) potassium chlorite potassium chlorate potassium perchlorate potassium carbonate Return to TOC Copyright © Cengage Learning. All rights reserved 112

Naming Compounds Exercise Examine the following table of formulas and names. Which of the compounds are named correctly? a) b) c) d) I, III, IV I only Formula Name I P 2 O 5 Diphosphorus pentoxide II Cl. O 2 Chlorine oxide III Pb. I 4 Lead iodide IV Cu. SO 4 Copper(I) sulfate Return to TOC Copyright © Cengage Learning. All rights reserved 113

Naming Compounds • Only Formula I is named correctly. • Formula II is chlorine dioxide. • Formula III is lead(IV) iodide. • Formula IV is copper(II) sulfate. Return to TOC Copyright © Cengage Learning. All rights reserved 114

Naming Compounds Acids • • • Acids can be recognized by the hydrogen that appears first in the formula—HCl. Molecule with one or more H+ ions attached to an anion. Most lab acids are either: binary acids ( composed of Hydrogen and another element) or oxyacids (composed of Hydrogen, oxygen and a third element Return to TOC Copyright © Cengage Learning. All rights reserved 115

Naming Compounds Return to TOC Copyright © Cengage Learning. All rights reserved 116

Naming Compounds Rules for Naming Acids • • If the anion does not contain oxygen, the acid is named with the prefix hydro– and the suffix –ic attached to the root name for the element. Examples: HCl Hydrochloric acid HCN Hydrocyanic acid H 2 S Hydrosulfuric acid Return to TOC Copyright © Cengage Learning. All rights reserved 117

Naming Compounds Acids That Do Not Contain Oxygen Return to TOC Copyright © Cengage

Naming Compounds Rules for Naming Acids • If the anion contains oxygen: § The suffix –ic is added to the root name if the anion name ends in –ate. • Examples: HNO 3 Nitric acid H 2 SO 4 Sulfuric acid HC 2 H 3 O 2 Acetic acid Return to TOC Copyright © Cengage Learning. All rights reserved 119

Naming Compounds Rules for Naming Acids • If the anion contains oxygen: § The suffix –ous is added to the root name if the anion name ends in –ite. • Examples: HNO 2 Nitrous acid H 2 SO 3 Sulfurous acid HCl. O 2 Chlorous acid Return to TOC Copyright © Cengage Learning. All rights reserved 120

Naming Compounds Some Oxygen-Containing Acids Return to TOC Copyright © Cengage Learning. All rights

Naming Compounds Flowchart for Naming Acids Return to TOC Copyright © Cengage Learning. All

Naming Compounds Exercise Which of the following compounds is named incorrectly? a) KNO 3 b) Ti. O 2 c) Sn(OH)4 d) PBr 5 e) H 2 SO 3 potassium nitrate titanium(II) oxide tin(IV) hydroxide phosphorus pentabromide sulfurous acid Return to TOC Copyright © Cengage Learning. All rights reserved 123

Naming Compounds • The correct answer is “b”. • The charge on oxygen is 2–. • Since there are two oxygen atoms, the overall charge is 4–. • Therefore, the charge on titanium must be 4+ (not 2+ as the Roman numeral indicates). Return to TOC Copyright © Cengage Learning. All rights reserved 124

Naming Compounds Examples • • • Sodium hydroxide § Na. OH Potassium carbonate § K 2 CO 3 Sulfuric acid § H 2 SO 4 Dinitrogen pentoxide § N 2 O 5 Cobalt(III) nitrate § Co(NO 3)3 Return to TOC Copyright © Cengage Learning. All rights reserved 125

Naming Compounds Exercise A compound has the formula XCl 3 where X could represent a metal or nonmetal. What could the name of this compound be? a) b) c) d) phosphorus trichloride carbon monochloride tin(IV) chloride magnesium chloride Return to TOC Copyright © Cengage Learning. All rights reserved 126

Naming Compounds • • • Phosphorus trichloride. Carbon monochloride has the formula CCl. Tin(IV) chloride has the formula Sn. Cl 4. Magnesium chloride has the formula Mg. Cl 2. Phosphorus trichloride has the formula PCl 3 and is therefore the correct answer Return to TOC Copyright © Cengage Learning. All rights reserved 127

Naming Compounds Lets Practice Some More! HF Hydroflouric acid Na 2 CO 3 Sodium carbonate H 2 CO 3 Carbonic acid KMn. O 4 Potassium permanganate HCl. O 4 Perchloric acid H 2 S Hyrdogen sulfuric acid Na. OH Sodium hydroxide Copper (II) sulfate or Cupric sulfate Cu. SO 4 Lead (II) chromate or Plubous chromate Pb. Cr. O 4 H 2 O NH 3 Hydrooxic acid (no……just water) Nitrogen trihydride (no. . just ammonia) Return to TOC 128

Naming Compounds Return to TOC Copyright © Cengage Learning. All rights reserved 129

Naming Compounds Writing Chemical formulas Return to TOC Copyright © Cengage Learning. All rights

Naming Compounds Identifying Ionic Charges • Group A elements – use the periodic table to determine ionic charge * elements in same group have same ionic charge * Group 4 A and Noble gases – almost never form ions • Group B elements – many have more than one ionic charge 131 Return to TOC

Naming Compounds Identifying Ionic Charges http: //wps. prenhall. com/wps/media/objects/476/488316/ch 04. html Charge on cations corresponds to group #. Charge on anions is found by subtracting 8 by group number 132 the number 8 is used b/c it represents # of valence e- in Noble gases Return to TOC

Naming Compounds Naming Cations and Anions • • Potassium ion Copper (II) ion Chloride ion Oxide ion Ba 2+ S 2 Au 3+ • • • Nitrite ion Hydroxide ion Phosphate ion SO 42 Cr. O 42 Cl. O 32133 Return to TOC

Naming Compounds Binary Ionic Compounds • Compounds composed of 2 different monatomic elements • To write binary formulas – write cation first, then anion *criss-cross charges to determine how many of each ion you need *use subscripts to denote number of ions ex: Ca 2+ + Cl 1 Ca. Cl 2 Na 1+ + Cl 1 - Na. Cl 134 Return to TOC

Naming Compounds Ternary Ionic Compounds • Compounds containing at least one polyatomic ion; at least 3 different elements • To write ternary formulas: write cation first, then anion *criss-cross charges to determine how many of each ion you need *use subscripts to denote number of ions *must use parentheses around polyatomic if more than one is needed!!! ex: Na 1+ + SO 32 Na 2 SO 3 Mg 2+ + OH 1 Mg. OH 2] Mg(OH)2 [not same as 135 Return to TOC

Naming Compounds Ionic Compounds • • • Na. NO 3 Ca. SO 4 (NH 4)2 O Cu. SO 3 Fe(OH)3 Na. F • • • Lithium sulfide Iron (III) phosphide Magnesium fluoride Barium nitrate Aluminum hydroxide Potassium phosphate Practice making ionic compounds! 136 Return to TOC

Naming Compounds Molecular Compounds • • • P 2 O 5 N 2 O NO 2 CBr 4 CO 2 • • • tetraiodine nonoxide sulfur hexafluoride nitrogen trioxide carbon tetrahydride phosphorus trifluoride 137 Return to TOC

Naming Compounds Examples of Ionic Compounds with Two Elements Formula Ions Cation Anion Name Na. Cl Na+ Cl– sodium chloride K 2 S K+ S 2– potassium sulfide Mg. O Mg 2+ O 2– magnesium oxide Ca. I 2 Ca 2+ I– calcium iodide Al 2 O 3 Al 3+ aluminum sulfide S 2– 138 Return to TOC

Naming Compounds Learning Check Write the formulas and names for compounds of the following ions: Br– S 2− N 3− Na+ Al 3+ 139 Return to TOC

Naming Compounds Solution Br− S 2− N 3− Na+ Na. Br Na 2 S sodium bromide sodium sulfide Na 3 N sodium nitride Al 3+ Al. Br 3 aluminum bromide Al. N aluminum nitride Al 2 S 3 aluminum sulfide 140 Return to TOC

Naming Compounds Transition Metals Form Positive Ions Most transition metals and Group 4(14) metals, § Form 2 or more positive ions § Zn 2+, Ag+, and Cd 2+ form only one ion. 141 Return to TOC

Naming Compounds Guide to Writing Formulas from the Name 142 Return to TOC

Naming Compounds Writing Formulas Write a formula for potassium sulfide. STEP 1 Identify the cation and anion. potassium = K+ sulfide = S 2− STEP 2 Balance the charges. K+ S 2− K+ 2(1+) + 1(2–) = 0 STEP 3 Write the cation first. 2 K+ and 1 S 2− = K 2 S 143 Return to TOC

Naming Compounds Writing Formulas Write a formula for iron(III) chloride. STEP 1 Identify the cation and anion. iron (III) = Fe 3+ (III = charge of 3+) chloride = Cl− STEP 2 Balance the charges. Fe 3+ Cl− Cl− 1(3+) + 3(1–) = 0 STEP 3 Write the cation first. 1 Fe 3+ and 3 Cl− = Fe. Cl 3 144 Return to TOC

Naming Compounds Learning Check The correct formula for each of the following is: A. copper(I) nitride 1) Cu. N 2) Cu. N 3 3) Cu 3 N B. lead(IV) oxide 1) Pb. O 2 2) Pb. O 3) Pb 2 O 4 145 Return to TOC

Naming Compounds Solution The correct formula for each of the following is: A. copper(I) nitride 3) Cu 3 N 3 Cu+ + N 3– = 3(1+) + (3–) = 0 B. lead(IV) oxide 1) Pb. O 2 Pb 4+ + 2 O 2– = (4+) + 2(2–) = 0 146 Return to TOC

Naming Compounds Unit 5 Part B Return to TOC Copyright © Cengage Learning. All

Naming Compounds Percent Composition, Empirical Formulas, Molecular Formulas Return to TOC

Naming Compounds Formula Masses and Molar masses: • Molecular mass or molecular weight are used instead of the term formula mass. • The formula mass of any compound is the sum of the average atomic masses of all of the atoms present in the formula Return to TOC 149

Naming Compounds Example of formula mass • H 2 O • 2 H atom weigh 1. 0079 each • 1 O atom weighs 15. 9994 each • 2 x 1. oo 79 • +1 x 15. 9994 • 18. 0153 formula mass for water Return to TOC 150

Naming Compounds Molar mass as a conversion factor • Moles x grams/mole = mass in grams • Mass in grams x 1 mol/grams = moles • Thus 2 conversions relate mass in grams to numbers of moles of a substance Return to TOC Copyright © Cengage Learning. All rights reserved 151

Naming Compounds Example • What is the molar mass of Barium nitrate Ba(NO 3)2 • • Solution 1 mol Ba x 137. 33 g/1 mol Ba = 137. 33 g Ba 2 moles N x 14. 0067 g/1 mole N = 28. 0134 g N 6 moles O x 15. 999 g/1 mol O = 95. 9964 g • Molar mass Ba(NO 3)2 = 261. 34 Return to TOC Copyright © Cengage Learning. All rights reserved 152

Naming Compounds Example • What is the mass in grams of 2. 5 moles

Naming Compounds Return to TOC

Percent Composition • Percent Composition – the percentage each element in a compound by mass of Percent = Part _______ Whole x 100% So… Percent composition of a compound or = molecule Mass of element in 1 mol __________ Mass of 1 mol x 100%

Percent Composition Example: What is the percent composition of Potassium Permanganate (KMn. O )? 4 Molar Mass of KMn. O K= 4 1(39. 1) = 39. 1 Mn = 1(54. 9) = 54. 9 O = 4(16. 0) = 64. 0 MM = 158 g

Percent Composition Example: What is the percent composition of Potassium Permanganate (KMn. O )? 4 Molar Mass of KMn. O % K % Mn K= 1(39. 10) = 39. 1 Mn = 1(54. 94) = 54. 9 O = 4(16. 00) = 64. 0 MM = 158 % O 39. 1 g K 158 g 54. 9 g Mn 158 g 64. 0 g O 158 g = 158 g 4 x 100 = 24. 7 % 34. 8 % 40. 5 %

Percent Composition Determine the percentage composition of sodium carbonate (Na CO )? 2 3 Molar Mass Na = 2(23. 00) = 46. 0 C = 1(12. 01) = 12. 0 O = 3(16. 00) = 48. 0 MM= 106 g Percent Composition % Na = % C = % O = 46. 0 g 106 g 12. 0 g 106 g 48. 0 g 106 g x 100% = 43. 4 % x 100% = 11. 3 % x 100% = 45. 3 %

Percent Composition Determine the percentage composition of ethanol (C H OH)? 2 5 % C = 52. 13%, % H = 13. 15%, % O = 34. 72% ________________________ Determine the percentage composition of sodium oxalate (Na C O )? 2 2 4 % Na = 34. 31%, % C = 17. 93%, % O = 47. 76%

Percent Composition Calculate the mass of bromine in 50. 0 g of Potassium bromide. 1. Molar Mass of KBr K = 1(39. 10) = 39. 10 Br =1(79. 90) =79. 90 MM = 119. 0 2. 79. 90 g ______ = 0. 6714 119. 0 g 3. 0. 6714 x 50. 0 g = 33. 6 g Br

Percent Composition Calculate the mass of nitrogen in 85. 0 mg of the amino acid lysine, C H N O. 6 14 2 2 1. Molar Mass of C H N O 6 14 2 2 C = 6(12. 01) = 72. 06 H =14(1. 01) = 14. 14 N = 2(14. 01) = 28. 02 O = 2(16. 00) = 32. 00 MM = 146. 2 2. 28. 02 g ______ = 0. 192 146. 2 g 3. 0. 192 x 85. 0 mg = 16. 3 mg N

Hydrates Hydrated salt – salt that has water molecules trapped within the crystal lattice Examples: Cu. SO • 5 H O , Cu. Cl • 2 H O 4 2 2 2 Anhydrous salt – salt without water molecules Examples: Cu. Cl 2 Can calculate the percentage of water in a hydrated salt.

Percent Composition Calculate the percentage of water in sodium carbonate decahydrate, Na CO • 10 H O. 2 3 2 1. Molar Mass of Na CO • 10 H O 2 3 2 Na = 2(22. 99) = 45. 98 C = 1(12. 01) = 12. 01 H = 20(1. 01) = 20. 2 3. O = 13(16. 00)= 208. 00 180. 2 g _______ MM = 286. 2 2. 286. 2 g Water H = 20(1. 01) = 20. 2 O = 10(16. 00)= 160. 00 MM = 180. 2 or H = 2(1. 01) = 2. 02 O = 1(16. 00) = 16. 00 MM H 2 O = 18. 02 So… 10 H O = 10(18. 02) = 180. 2 2 x 100%= 67. 97 %

Percent Composition Calculate the percentage of water in Aluminum bromide hexahydrate, Al. Br • 6 H O. 3 2 1. Molar Mass of Al. Br • 6 H O 3 2 Al = 1(26. 98) = 26. 98 Br = 3(79. 90) = 239. 7 H = 12(1. 01) = 12. 12 O = 6(16. 00) = 96. 00 MM = 374. 8 2. Water H = 12(1. 01) = 12. 1 O = 6(16. 00)= 96. 00 MM = 108. 1 or MM = 18. 02 For 6 H 2 O = 6(18. 02) = 108. 2 3. 108. 1 g _______ 374. 8 g x 100%= 28. 85 %

Percent Composition If 125 grams of magnesium sulfate heptahydrate is completely dehydrated, how many grams of anhydrous magnesium sulfate will remain? Mg. SO 1. Molar Mass Mg = 1 x 24. 31 = 24. 31 g S = 1 x 32. 06 = 32. 06 g O = 4 x 16. 00 = 64. 00 g MM = 120. 37 g 2. % Mg. SO 4 . 7 H O 2 4 120. 4 g 246. 5 g X 100 = 3. Grams anhydrous Mg. SO H = 2 x 1. 01 = 2. 02 g O = 1 x 16. 00 = 16. 00 g MM = 18. 02 g MM H O = 2 g = 126. 1 g 7 x 18. 02 Total MM = 120. 4 g + 126. 1 g = 246. 5 g 0. 4884 x 125 = 48. 84 % 4 61. 1 g

Percent Composition If 145 grams of copper (II) sulfate pentahydrate is completely dehydrated, how many grams of anhydrous copper sulfate will remain? Cu. SO 1. Molar Mass Cu = 1 x 63. 55 = 63. 55 g S = 1 x 32. 06 = 32. 06 g O = 4 x 16. 00 = 64. 00 g MM = 159. 61 g 2. % Cu. SO 4 . 5 H O 2 4 159. 6 g 249. 7 g X 100 = 3. Grams anhydrous Cu. SO H = 2 x 1. 01 = 2. 02 g O = 1 x 16. 00 = 16. 00 g MM = 18. 02 g MM H O = 2 g = 90. 1 g 5 x 18. 02 Total MM = 159. 6 g + 90. 1 g = 249. 7 g 0. 6392 x 145 = 63. 92 % 4 92. 7 g

Percent Composition A 5. 0 gram sample of a hydrate of Ba. Cl was heated, and only 4. 3 grams of the 2 anhydrous salt remained. What percentage of water was in the hydrate? 1. Amount water lost 5. 0 g hydrate - 4. 3 g anhydrous salt 0. 7 g water 2. Percent of water 0. 7 g water 5. 0 g hydrate x 100 = 14 %

Percent Composition A 7. 5 gram sample of a hydrate of Cu. Cl was heated, and only 5. 3 grams of the 2 anhydrous salt remained. What percentage of water was in the hydrate? 1. Amount water lost 7. 5 g hydrate - 5. 3 g anhydrous salt 2. 2 g water 2. Percent of water 2. 2 g water 7. 5 g hydrate x 100 = 29 %

Percent Composition A 5. 0 gram sample of Cu(NO ) • n. H O is heated, and 3. 9 g of the anhydrous salt remains. 32 2 What is the value of n? 1. Amount water lost 5. 0 g hydrate - 3. 9 g anhydrous salt 1. 1 g water 3. Amount of water 0. 22 x 18. 02 = 2. Percent of water 1. 1 g water 5. 0 g hydrate x 100 = 22 % 4. 0

Percent Composition A 7. 5 gram sample of Cu. SO • n. H O is heated, and 5. 4 g of the anhydrous salt remains. 4 2 What is the value of n? 1. Amount water lost 7. 5 g hydrate - 5. 4 g anhydrous salt 2. 1 g water 3. Amount of water 0. 28 x 18. 02 = 2. Percent of water 2. 1 g water 7. 5 g hydrate x 100 = 28 % 5. 0

Formulas Percent composition allow you to calculate the simplest in compound. ratio among the atoms found Empirical Formula – formula of a compound that expresses ratio of atoms. lowest whole number Molecular Formula – actual formula of a compound showing present the number of atoms Examples: C H 4 10 C H 2 5 - molecular C H O 6 12 6 - molecular - empirical CH O 2 - empirical

Formulas Is H O an empirical or molecular formula? 2 2 Molecular, it can be reduced to HO HO = empirical formula

Calculating Empirical Formula An oxide of aluminum is formed by the reaction of 4. 151 g of aluminum with 3. 692 g of oxygen. Calculate the empirical formula. 1. Determine the number of grams of each element in the compound. 4. 151 g Al and 3. 692 g O 2. Convert masses to moles. 4. 151 g Al 1 mol Al = 0. 1539 mol Al = 0. 2308 mol O 26. 98 g Al 3. 692 g O 1 mol O 16. 00 g O

Calculating Empirical Formula An oxide of aluminum is formed by the reaction of 4. 151 g of aluminum with 3. 692 g of oxygen. Calculate the empirical formula. 3. Find ratio by dividing each element by smallest amount of moles. 0. 1539 moles Al = 1. 000 mol Al 0. 1539 0. 2308 moles O = 1. 500 mol O 0. 1539 4. Multiply by common factor to get whole number. (cannot have fractions of atoms in compounds) O = 1. 500 x 2 = 3 Al = 1. 000 x 2 = 2 therefore, Al O 2 3

Calculating Empirical Formula A 4. 550 g sample of cobalt reacts with 5. 475 g chlorine to form a binary compound. Determine the empirical formula for this compound. 4. 550 g Co 1 mol Co = 0. 07721 mol Co 58. 93 g Co 5. 475 g Cl 1 mol Cl = 0. 1544 mol Cl 35. 45 g Cl 0. 07721 mol Co 0. 1544 mol Cl =1 0. 07721 Co. Cl 2 =2

Calculating Empirical Formula When a 2. 000 g sample of iron metal is heated in air, it reacts with oxygen to achieve a final mass of 2. 573 g. Determine the empirical formula. Fe = 2. 000 g Fe 1 mol Fe O = 2. 573 g – 2. 000 g = 0. 5730 g = 0. 03581 mol Fe 55. 85 g Fe 0. 573 g O 1 mol O = 0. 03581 mol Fe 16. 00 g 1: 1 Fe. O

Calculating Empirical Formula A sample of lead arsenate, an insecticide used against the potato beetle, contains 1. 3813 g lead, 0. 00672 g of hydrogen, 0. 4995 g of arsenic, and 0. 4267 g of oxygen. Calculate the empirical formula for lead arsenate. 1. 3813 g Pb 1 mol Pb = 0. 006667 mol Pb 207. 2 g Pb 0. 00672 g. H 1 mol H = 0. 00667 mol H 1. 008 g H 0. 4995 g As 1 mol As = 0. 006667 mol As 74. 92 g As 0. 4267 g Fe 1 mol O 16. 00 g O = 0. 02667 mol O

Calculating Empirical Formula A sample of lead arsenate, an insecticide used against the potato beetle, contains 1. 3813 g lead, 0. 00672 g of hydrogen, 0. 4995 g of arsenic, and 0. 4267 g of oxygen. Calculate the empirical formula for lead arsenate. 0. 006667 mol Pb 0. 006667 0. 00667 mol H 0. 006667 mol As 0. 006667 0. 02667 mol O 0. 006667 = 1. 000 mol Pb = 1. 00 mol H = 1. 000 mol As = 4. 000 mol O Pb. HAs. O 4

Calculating Empirical Formula The most common form of nylon (Nylon-6) is 63. 38% carbon, 12. 38% nitrogen, 9. 80% hydrogen and 14. 14% oxygen. Calculate the empirical formula for Nylon-6. Step 1: In 100. 00 g of Nylon-6 the masses of elements present are 63. 38 g C, 12. 38 g n, 9. 80 g H, and 14. 14 g O. Step 2: 63. 38 g C 1 mol C = 5. 302 mol C 9. 80 g H 12. 01 g C 12. 38 g N 1 mol N 14. 01 g N 1 mol H = 9. 72 mol H 1. 01 g H = 0. 8837 mol N 14. 14 g O 1 mol O 16. 00 g O = 0. 8832 mol O

Calculating molecular formula • It is not possible to determine the correct molecular formula unless the molecular mass of the substance has been determined • The relationship between the simplest formula and the molecular mass is: • (simple formula)x = molecular formula • Where x is a whole number multiple of the simple formula

Calculating Molecular Formula A white powder is analyzed and found to have an empirical formula of P 2 O 5. The compound has a molar mass of 283. 88 g. What is the compound’s molecular formula? Step 3: Multiply Step 1: Molar Mass P = 2 x 30. 97 g = 61. 94 g O = 5 x 16. 00 g = 80. 00 g (P O ) = 2 52 141. 94 g Step 2: Divide MM by Empirical Formula Mass 238. 88 g 141. 94 g =2 P O 4 10

Calculating Molecular Formula A compound has an experimental molar mass of 78 g/mol. Its empirical formula is CH. What is its molecular formula? (CH) = 6 C = 12. 01 g H = 1. 01 g 13. 01 g C H 6 6 78 g/mol 13. 01 g/mol =6