Chapter 3Achemical bonds- what holds compounds together-bonds can be ionic or molecular/covalentchemical formula- shows the kinds and number of

each element in a compoundex- H2O CO2 H3PO4

structural formula- uses lines to show bondsex- OO ═ C ═ O

H H

empirical formula- gives the relative number of atoms of each element in a compound

-lowest whole number ratiomolecular formula- gives the actual number of

atoms of each element in a compoundex- hydrogen peroxideH2O2

emp. = HO (H and O in a 1:1 ratio)mol. = H2O2

page 87 Ex 3.1 and FP 3.1

atomic elements- exist in nature as single atoms-almost all the elements can exist as atoms-called monatomic

molecular elements- cannot exist in nature as one atom, cannot exist alone

-exist as moleculesH O N Cℓ Br I F-called diatomic

Ions- particles with a charge (+ or -), they have either lost or gained electrons

-in ions # of p+ ≠ # of e-

cation-ion with a positive charge-loses electrons-metallic elements lose electrons-look at Group # to get the charge for Groups 1A

to 3A

ex- sodium Na1+ or Na+1 or Na+

aluminum Aℓ3+

-sodium lost 1e-, aluminum lost 3 e-

**Most cations of the transition metals have more than one charge

-these will need to be given to youex- Pb4+ lost 4e-

-a few have only one chargeAg1+ Zn2+ Cd2+

-silver lost 1e-, zinc and cadmium each lost 2e-

anions-ion with a negative charge-gains electrons-non-metallic elements gain electrons-look at Group # - 8 to get the charge ex- chlorine Cℓ1-

arsenic As3-

-chlorine gained 1e-

-arsenic gained 3e-

*Group 4 elements do not generally form ions, Group 8 do not b/c they are inert

Naming IonsCations-name is the same as the element with the word ion-back to examplessodium ion aluminum ion lead (IV) ionAnions-drop ending and add –ide and the word ion-back to examples-chloride ion-arsenide ion

Try these!!-name the ion/tell if it is a cation or anion-tell the charge on the ion-tell how e- the ion has lost or gainedSr I Ca KP B S

polyatomic ions- made up or two or more atoms that carry a charge

*most names end in –ite or –ate

Ionic Compounds-compounds composed of cations and anions-made up of a metal (cation) and a non-metal

(anion)-usually solid crystals at room temp-have high melting points-are electrically neutral because # of p+ = # of e-

ex- NaCℓ KI Ca3N2

formula unit- chemical formula for an ionic compound

Molecular Compounds-made up of two or more non-metalsBinary Molecular Compounds-made up of two non-metalsEx- CO, CO2, CCℓ4

-to name molecular compounds you use prefixes

Prefix # (subscript)mono- 1di- 2tri- 3tetra- 4penta- 5hexa- 6hepta- 7octa- 8nona- 9deca- 10

Naming Molecular Compounds-look at subscript of each element and give each

element a prefix-if first element has a 1 as the subscript, then it

does not get a prefix (omit mono-)-second element gets prefix and ends in –ide-if element begins with a vowel, drop the vowel

at the end of a prefix **when writing formulas for molecular

compounds you DO NOT reduce subscripts

Try these!!carbon monoxide carbon tetrachloridesulfur trioxide tetriodine nonoxidephosphorus pentafluoride

N2O PCℓ3 SF6 OF2

CℓO8 NF3 S2Cℓ2 N2O4

Acids-acids are compounds dissolved in water-will have (aq) after the formula which means

aqueous or dissolved in water-always begin with hydrogen (H)Ex- HCℓ H2SO4 H3PO3

Naming Acids-you must look at what follows the hydrogen

-if it is a single element (ends in –ide), then you use prefix hydro-, root of the element, -ic ending and the word acid

ex- HCℓhydrochloric acid-if what follows hydrogen ends in –ite, you just

add –ous ending to root of the polyatomic ion and add acid

ex- H3PO3

phosphorous acid

-if what follows hydrogen ends in –ate, you just add –ic ending to root of the polyatomic ion and add acid

ex- H2SO4

sulfuric acidTry these!!HI H2S H2CO3

H2SO3 HNO2 HCℓO3

Chemical Equationsreactants productsreactant- starting substance in a chemical

reactionproduct- substance formed in a chemical

reaction= yields, gives you, produces, goes to**Law of Conservation of Mass holds true here

mass of reactants = mass of products

-the states of matter can be indicated after the substance

(s)=solid (ℓ)=liquid (g)=gas (aq)=aqueous= reversible reaction

catalyst- substance that speeds up the rate of a reaction without being used up in the reaction

**written above the arrowex- Pt ∆ = heat applied

**Remember H O N Cℓ Br I Fskeleton equation- chemical equation that is not

balancedex- Write a skeleton for the following reaction:solid iron reacts with oxygen to form solid iron

(III) oxide Fe + O2 Fe2O3

Try these:1) solid sodium hydrogen carbonate reacts with

hydrochloric acid to produce aqueous sodium chloride, water and carbon dioxide

2) solid sulfur burns in oxygen to form sulfur dioxide

3) solid potassium chlorate forms oxygen and solid potassium chloride in the presence of catalyst manganese(II) oxide

Answers1)NaHCO3(s) + HCℓ(aq) NaCℓ(aq) + H2O (ℓ)

+ CO2(g)

2) S(s) + O2(g) SO2(g)

3) KCℓO3(s) MnO O2(g) + KCℓ(s)

Balancing Equations-each side of the equation (reactants and

products) must have the same # of each element

-some may already be balanced-must be lowest whole # ratio-balance by putting coefficients in front of

compounds

Types of Chemical Reactions1) Combination/Synthesis Reaction-two or more substances combine to form a

single substancereactants- two elements or two compoundsproducts- always a compoundex- 2K + Cℓ2 2KCℓex- SO2 + H2O H2SO3

Try these!! Don’t forget to balance!!a) aluminum + oxygenb) copper + sulfur (two possible reactions)c) beryllium + oxygend) strontium + iodinee) magnesium + nitrogena) 4Aℓ + 3O2 2Aℓ2O3

b) 2Cu + S Cu2S or Cu + S CuSc) 2Be + O2 2BeO d) Sr + I2 SrI2

e) 3Mg + N2 Mg3N2

2) Decomposition Reaction-one compound breaks down or decomposes into

two simpler compounds-the reverse of synthesisex- 2H2O 2H2 + O2

Try these!!a) lead(IV) oxide b) hydrogen iodide c) hydrogen bromide d) sodium chloride

a) PbO2 Pb + O2

b) 2HI H2 + I2

c) 2HBr H2 + Br2

d) 2NaCℓ 2Na + Cℓ2

3) Single-Replacement Reactions-one element replaces a second element in a

compoundex- 2K + CaO K2O + Ca-whether one metal will replace another metal is

determined by reactivity of the metal

activity series of metals- lists metals in order of decreasing reactivity

ex- Mg + Zn(NO3)2 *is Mg above Zn on the reactivity series?Mg + Zn(NO3)2 Mg(NO3)2 + Zn

ex- Mg + Ag2SO4 Mg + Ag2SO4 MgSO4 + 2Ag

ex- Mg + LiNO3 -lithium is above magnesiumMg + LiNO3 no reaction

-Halogens can replace each other in single-replacement reactions

-Reactivity decreases as you go down the halogen group

Try These!!a) zinc + hydrogen sulfate b) chlorine + sodium bromide c) zinc + sodium nitrate d) iron(II) + lead(II) nitrate e) chlorine + sodium iodide

a) Zn + H2SO4 H2 + ZnSO4

b) Cℓ2 + 2NaBr Br2 + 2NaCℓc) Zn + NaNO3 no reactiond) Fe + Pb(NO3)2 Pb + Fe(NO3)2

e) Cℓ2 + 2NaI I2 + 2NaCℓ

4) Double-Replacement Reactions-involve an exchange of cations between two

reacting compoundsex- BaCℓ2 + K2CO3 BaCO3 + 2KCℓex- FeS + 2HCℓ H2S + FeCℓ2

Try These!!a) sodium hydroxide + iron(III) nitrate b) barium nitrate + hydrogen phosphate c) potassium hydroxide+hydrogen phosphate d) hydrogen sulfate + aluminum hydroxide

Answersa) 3NaOH + Fe(NO3) 3 3NaNO3 + Fe(OH)3

b) 3Ba(NO3) 2 + 2H3PO 4 Ba3(PO4) 2 + 6HNO3

c) 3KOH + H3PO4 K3PO4 + 3H2Od) 3H2SO4 + 2Aℓ(OH)3 Aℓ2(SO4)3 + 6H2O

5) Combustion Reaction-hydrocarbon combined with oxygen to produce

carbon dioxide and waterex- C6H6 + O2 CO2 + H2O-to balance:CxHy + O2 CO2 + H2O (x+y/4) (x) (y/2)C6H6 + 7.5O2 6CO2 + 3H2O-multiply by 2 to get whole number ratio2C6H6 + 15O2 12CO2 + 6H2O

Try These!!a) C14H26 + O2 CO2 + H2Ob) C8H12 + O2 CO2 + H2O

Answers!c) 2C14H26 + 41O2 28CO2 + 26H2Od) C8H12 + 11O2 8CO2 + 6H2O

Summary of Reactions1) Combination/SynthesisR + S RS2) Decomposition ReactionRS R + S3) Single-Replacement ReactionT + RS R + TS4) Double-Replacement ReactionRS + TU RU + TS5) Combustion ReactionCxHy + O2 CO2 + H2O