Deanna

   **Deanna’s Chemistry Notes **

**__ Definition Covalent Bond: __** A chemical link between two atoms. **Examples:** There is a [|covalent bond]  between the [|oxygen] and each [|hydrogen] in a water [|molecule] (H2O). Each of the [|covalent bonds][|electrons]  - one from a [|hydrogen] [|atom] and one from the [|oxygen] [|atom]. Both [|atoms]  share the [|electrons]  .Type in the content of your new page here. http://chemistry.about.com/od/chemistryglossary/a/covalentbonddef.htm

**__Definition of electronegativity :__** A measure of the tendency of an <span style="font-size: 80%; font-family: Tahoma,Geneva,sans-serif;">[|atom] (or moiety) to withdraw [|electron]s from structures to which it is [|bond] ed. In most circumstances, for example, sodium tends to donate [|electron] [|density][|electronegativity] <span style="font-size: 72%; font-family: Tahoma,Geneva,sans-serif;">) and fluorine tends to withdraw <span style="font-size: 80%; font-family: Tahoma,Geneva,sans-serif;">[|electron] [|density] (it has a high [|electronegativity] <span style="font-size: 72%; font-family: Tahoma,Geneva,sans-serif;">). <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 72%;"> are shared between them. contains two (it has a low <span style="color: rgb(0, 0, 0); display: block; text-align: left; font-size: 96%;"><span style="font-family: 'Courier New',Courier,monospace;">http://www.everythingbio.com/glos/definition.php?word=electronegativity <span style="font-size: 72%; font-family: Tahoma,Geneva,sans-serif;"> http://grandinetti.org/Teaching/Chem121/Lectures/LewisDot/index.html

<span style="font-size: 150%; font-family: 'Arial Black',Gadget,sans-serif;"> <span style="color: rgb(0, 0, 0); display: block; text-align: left; font-family: Impact,Charcoal,sans-serif;"><span style="color: rgb(172, 0, 255); display: block; font-size: 60%; font-family: 'Arial Black',Gadget,sans-serif; text-align: left;">Notes <span style="font-size: 90%; font-family: 'Courier New',Courier,monospace;"> <span style="color: rgb(172, 0, 255); display: block; font-size: 60%; font-family: 'Arial Black',Gadget,sans-serif; text-align: left;">Naming Covalent Bonds 1.) Elements are listed by lower group first 2.) If both elements are in the same group, the lower atomic number element is the first of the bond. 3.) 2nd element will end with -ide 4.) Prefixes are used to tell how many atoms are in the bond(mono,bi,tri,etc) 5.) First element will only have a prefix if it is more than one.

Examples: BF 3- Boron trifluoride Dinitrogen pentaoxide- N 2 O <span style="color: rgb(172, 0, 255); display: block; font-size: 60%; font-family: 'Arial Black',Gadget,sans-serif; text-align: left;">3 <span style="font-size: 90%; color: rgb(172, 0, 255); display: block; font-family: 'Arial Black',Gadget,sans-serif; text-align: left;">Defining aCovalent Bond //*** Covalent Bonds**//: one or more bonds made between elements when the bond is made by the //sharing// of electrons. //*** Triple bond**//- sharing of 6 electrons between 2 elements. <span style="display: block; font-size: 60%; font-family: 'Arial Black',Gadget,sans-serif; text-align: left; color: rgb(172, 0, 255);"><span style="font-size: 140%; font-family: Impact,Charcoal,sans-serif;">Drawing the Lewis Dot Structures 1.) Draw the Lewis Dot Structure for each element. 2.) Place the element having the most unpaired electrons in the center. 3.) Bond as many single elements to thee center element as possible- keep balance as you draw 4.) Creat double/triple bonds as necessary to reach the octet for all elements
 * //* Single bond//**- sharing of 2 electrons between 2 elements.
 * //* Double bond//**- sharing of 4 electrons between 2 elements.

Drawing Ions (with a change) Exceptions to Octet Rule <span style="color: rgb(196, 28, 65);">[[file:Explore Learning – Covalent Bonds Gizmo.doc] <span style="display: block; color: rgb(211, 13, 13); text-align: left;">__P-orbital__2 e' total 1 bond location O sphere 6e' totalO- sigma bond first bond area __S-Orbital__<span style="display: block; color: rgb(211, 13, 13); text-align: left;"> <span style="display: block; color: rgb(211, 13, 13); text-align: center;">pie symbol- pi bonds<span style="display: block; color: rgb(220, 9, 9); text-align: left;"> 3 additional areas <span style="display: block; color: rgb(211, 13, 13); text-align: left;"> 3 bond locationshybridiation: classifying bondsS Sp Sp2 Sp3Examples see Notes __** Notes 2-13-09 **<span style="font-size: 180%; color: rgb(44, 27, 27);">Chemical EquationsTheir job: Depict the kind of <span style="color: rgb(223, 12, 12);">reactants and <span style="color: rgb(255, 122, 0);">products and their relative amounts in a reaction.<span style="color: rgb(61, 250, 41);">4 Al(s) +<span style="color: rgb(25, 209, 16);"> 3 O2 (g) <span style="color: rgb(242, 112, 28);">2Al2O3(s) The n<span style="color: rgb(64, 252, 44);">umbers in the front are called <span style="color: rgb(38, 235, 30);">stoichiometric coefficients The letters (s), (g), and (l) are the physical states of compounds. __**Introduction:**__- chemical reactions occur when bonds between the outermost parts of atoms are formed or broken.-Chemical reactions involve changes in matter, the making of new materials with new properties, and energy changes.- Symbols represent elements, formulas describe compounds, chemical equations describe a chemical reaction.Parts of a reaction EquationC+O2 CO2-This reads " carbon plus oxygen react to yield carbon dioxide"Chemical EquationsBecause of the principle of the <span style="color: rgb(231, 13, 13);">conservation of matter, an <span style="color: rgb(231, 13, 13);">equation must be balanced. It must have the same number of atoms of the same kind on both sides.Balancing EquationsYou may __//**<span style="font-size: 160%; color: rgb(243, 63, 63);">NOT **// __change the subscripts<span style="color: rgb(248, 236, 99);">2 H2+ O2 <span style="color: rgb(246, 227, 49);">2 H2O4Al(s)+ 3O2(g)2Al2O3(s)This equation means 4 AL atoms + 3 O2 moleculesProduces2 molecules of Al2O3and/or4 moles of Al + 3 moles of O2producesSteps To Balancing EquationsWrite the correct formula for the reactants and the productsFind the number of atoms for each element an the left side. Compare those against the number of atoms of the same element on the other side.Determine where to place coefficients in front of formulas so that the left side has the same number of atoms as the right side for EACH element in order to balance equations.Check your answer to see if.The numbers of atoms on both sides of the equation are now balancedThe coefficents are in the lowest possible whole number ratios (reduced)Suggestions to helpTake one element at a time, working left to right except for H and O. Save H for next to last and O until last.If everything balances execpt for O and there is no way to balance O with a whole number, double all the cofficients and try again ( Because O is diatomic as an element)(Shortcut) Polyatomic ions that appear on both sides of the equation should be balanced as indepentent units.Example to balance2H2(g) + o2(g) 2H2O(i)__Notes 2/18/09Synthesis ReactionsSynthesis- combinging one or more elements or compounds to form a single product.2Mg(s) + O2 (g) -- 2MgO (s)S(s) + O2 (g)- SO2 (g)You try these1) Beryllium + Oxygen - BeO2) Magnesium + Nitrogen -- Mg3N23) Potassium + chlorine KClDecomposition * A chemical change in which a single compound breaks down into 2 simpler compounds.* 2HgO(s) -- 2Hg(l) + o2 (g)* 2H2O--- 2H2 (g) + O2 (g)ExampleHydrogen iodide-- HI(g) -- H2+ I2Decomposing a CarbonateAny time you have a compound with carbonate in it, it decomposes the same way* XCO3-- XO+CO2.X any positive charge cationSingle ReplacementA chemical change in which one element replaces a second element in a bond* 2K (s) + 2HOH (I)-- 2KOH (aq) + H2 (g)* Zn(s) + Cu(NO3)2(ag) - Cu(s) + Zn(NO3)2 (aq)Single ReplacementA chemical change in which one element replaces anther element.Zinc + Sulfuric Acid (H2SO4)--Zn + H2SO4 -- ZnSO4 + H2Ca + HOH - Ca (OH)2 + HDouble ReplacementA chemical change involving an exchange of positive ions between 2 compoundsNa2S (aq) + Cd(NO3)2(aq)--- CdS(s) + 2NaNO3 (aq)<span style="color: rgb(176, 12, 174);">A <span style="color: rgb(196, 28, 65); font-size: 170%;"><span style="color: rgb(65, 29, 124);">cid - Base ReactionsThe neutralizing of an acid with a hydroxideJust like a double replacement reaction: can tell because water is formed as a product2H3PO4 + 3Ca(OH)2>>>>> 6HOH + Ca3(PO4)2Forming Water 6HOHCombustion ReactionReaction involving the burning of an organic compound.Will always form CO2 & H2OC3H8 + 5O2>>>>>> 3CO2 + 4H2OWill a reaction really happen?Using your activity series chartThis uses electronegativity values to determine which element "owns" more of the electronIf the single element is higher on Activity Seris, it will form a new compound. This means it would "own" more of the electron.Examples:Br2 + Kl>>> will happen because Br is higher than IBr2 + KCL>>>> won't happen because Cl is higher than Br Double Replacement ReactionsWhen a DR happens one of the two products must be a g s or water.Otherwise the reaction wont happenNa3PO4 (aq) + 3KCL (aq) >>>>> 3Nacl(aq) + K3PO4 (aq)123628171812362817181236281718123628171812362817181236281718123628171812362817181236281718123628171812362817181236281718123628171812362817181236281718 123628171812362817181236281718123628171812362817181236281718123628171812362817181236281718123628171812362817181236281718123628171812362817181236281718
 * Carbonate (Co 3 )-2
 * The -2 means that you will have to add two extra electrons to have all elements reach the octet rule.
 * Elements with 3,5,&7 valence electrons
 * Can be stable without meeting the Octet rule
 * 3w/6 electrons bonding
 * 5w/10 electrons bonding
 * 7w/14 electrons bonding


 * Stoichiometry Chapter 8**

Using info from our balanced equations

Review If you have 34.1 g of CuSO4 how many moles and molecules do you have. Moles= 1mol/159.6 g CuSO4 Molecules= * 6.022x 1o'23

Conservation of Mass
 * the total mass remains constant when comparing reactants and products (the two equal.)
 * H2(g) + I2(g) >>>> 2HI(l)
 * the total mass will equal the mass of hydrogen iodide.

Writing Mole Ratios
 * this uses the coefficients of a balanced equation to show the relationship between compounds.
 * N2 (g) + 3H2 >>>> 2 NH3 (g)
 * what this means: 1 mol N2 = 2 mol NH3 = 3 mol H2

Mole>>> Mole Calculations
 * how many moles of NH3 are produced when 0.60 mol of nitrogen reacts with hydrogen? N2 (g) + 3H2 >>> 2NH3 (g)
 * .60 mol N2 X 2mol NH3 / 1 mol N2 = 1.20 mol NH3

Practice 2H2 + O2>>>>> 2H2O
 * If you have 3.1 mol of water, how many moles of H2 did you begin with? Write the balanced equations.

3.1 mol H2O X 2H2/2H2O= 3.1 mol of H2

3.1 mol X 1mol O2/ 2 mol H2o = 1.55 mol O2

Moles<<<>>>Grams N2 (g) + 3H2 (g) >>> 2NH3 (g) You can convert from grams>> mol>> grams using the mol:mol ratios If you have 3.21 g of N2 how many g of NH3 will be produced?

3.21gN2 X 1molN2/28.02g N2 X 2 mol NH3/ 1 mol N2 X 17.03 NH3/1 mol NH3 = 3.90 g NH3

Notes 3/12/09

Limiting & Excess Reagents


 * In a chemical reaction, one compound drives how long and how much a reaction can occur.
 * Limiting- determines how much product can be formed
 * Excess- some left over during the reaction process

How to do the problem
 * Convert the grams of each reactant into moles of the product.
 * The smaller mole valuve tells you which starting reactant is the limiting reactant.
 * Use the moles of the limiting reagent to calculate the amount of product produced.

Sample Problem 2 Cu + S >>> Cu2S
 * copper reacts with S to form copper l sulfide according to the following equation.
 * What is the limiting reagent when 80.0 g Cu reacts with 25.0 g S

80.0Cu/1 X 1molCu/ 63.545gCu X 1molCu2S/ 2 molCu = .629 mol Cu2S

25.ogS/1 X 1molS/32.1g X 1molCu2S/ 1molS = .779 mol Cu2S

2) Cu produces .629 moles Cu2S S produces .779 moles Cu2S Therefore, Cu is the limiting reagant and must be used to answer all questions What???? Solve the proble using Cu moles. This will tell you how much product can be formed.

CHAPTER 9 _+_+_+__+_+_+_+_+_+___+++_+_+_+_+++_+_++__+_++_+___+___+_+_+_+_+_+_+_|+__+__+_+_+_+_+_+____+_+__+_+_+_+_+_+|_+_+_+_+_+

Elements that exist as gases at 25 degrees celius and 1 atmosphere.

Physical Characteristics of Gases
 * Gases assume the volume and shape of their containers
 * Gases are the most compressibole state of matter
 * Gases will mix evenly and completely when confined to the same container
 * Gases have much lower densities than liquids and solids

Pressure equals = force/ Area

Units of Pressure 1 pascal)= 1 N/m"2 1 atm= 760 mmHg = 760 toit 1 atm = 101.325 kPa = 101.325 Pa

As P(h) increases V decreases

Boyles Law

Pª (a= directly related to) 1/V PxV= constant P1x V1= P2 x V2

Constant temperature Constant amount of gas

A sample of chlorine gas accupies a volume of 946 ml at a pressure of 726 mm Hg. What is the pressure of the gas ( in mmHg) If the volume is reduced at constant temperature to 754 ml?

P1 x V1 = P2 x V2 P1 = 726 mmHg P2 = ? V1= 946 ml V2= 154ml

P2= P1x V1/ V2 = 726 mmHg x 946 ml/ 154 ml = 4460mmHg

Charles Law & Gay- Lussac's Law

Variation of gas with tempuue at constant pressure

V constant x T V1/T1= V2/T2

Tempertaure must be in Kelvin T(K)= t(c)+ 273.15

Temputure Conversion T,k= Kelvin, eliminates negative temperatures
 * T,c= 5/9 (T,f - 32)
 * T,k= T,c + 273.15

V1/V1 = V2/V2 V1= 3.2o L V2= 1.54L T1= 398.15k T,2= ? T2= V2xT1/ V1= 1.54Lx 398.15k/ 3.20L = 192K

Ideal Gas Equation Boyle's law: Vª 1/p ( at constant n and t) Charles law: V ª T (at constant n and p) Avogardo's law: V ª n ( at constant P and T) Vª nT/ P n= number of moles V= constant x nT/ P= R nT/P R is the gas constant PV = nRT

The conditions 0 degrees C and 1 atm are called standared temperature and pressure (STP) Experiments show that at STP, 1 mole of an ideal gas occupies 22.414L

PV= nRT R= PV/nT = (1 atm) (22.414L)/ (1 mol) (273.15K) R= .082057 L x atm/ (mol x K)

T= 0 degrees C = 273.15 P= 1 atm PV= nRT/P

n= 49.8g x 1mol HCl/ 36.45 g HCl= 1.37 mol

V= 1.37mol x .0821 x Lxatm/mol K X 273.15K _ DIVIDEI 1 atm

V= 30.6 L

DALTON's LAW OF PARTIAL PRESSURES

P,(A) P, (B) P(total) = P(A) + P(B)

Consider a case in which two gases, A and B are in a container of volume V.

P(A) = n(A)RT/ V n(A) is the # of moles of A P(B) = n(B)RT/ V n(B) is the # of moles of B

P(T) = P(A) = P(B) X(A)= n(A)/ n(A) + n(B) X(B) = n(B)/ n(A) + n(B)

P(i) = X(i)P(T)

i= in the gas

A sample of natural gas contains 8.24 moles of CH4 .0421 moles of C2H8 and .116 moles of C3H8. If the total pressure of the pressure of the gases in 1.37 atm, what is the partial pressure of propane (C3H8) ?

P(i)= X(i)P(T) P(T)= 1.37 atm

X propane = .116/ 8.24 + .421 + .116 = .0132

P propane = .0132 x 1.37 atm = .0181 atm ___________________________________________________________________________________________________________________________ Solution: A homogenous mixture, in which the componets are uniformly intermingled.

Solvent: The substance present in the largest amount

Solute: the other substances are called solutes

Aqueous Solution: a solution in which the solvent is water

Solubility: The amount of a substance that dissolves in a given volume of solvent at a given temputure

Saturated and unscaturated solutions: Even for every soluble substances there is a limit to the amount of solute that can be dissolved in a given amount of solvent

When a solution can dissolve as much solute as will be dissolved at that temperature, it is said to be saturated. A solution that has not reached the limit ofsolute it will dissolve in it is to be unsaturated

<span style="color: rgb(128, 0, 128);">Once you hit the saturation point, nothing dissolves any more, it just settles on the bottom

In a saturated solution an equilibrium is reached between dissolving and recrystallization

Temperature and Solubility

- solubility is influenced by temperature - In warmer water, more solid will dissolve. - This is because a high temperature means H2O molecules are moving faster (keeping more solid molecules suspend). - Conversely a gas will be less soluble at a higher temperature - THis is because when gas molecules are moving faster they are able to escape from the liquid surface - Think of cold soda vs. warm soda. Warm soda goes flat fasster.

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