UNIT TWO: CHEMISTRY

UNIT TWO: CHEMISTRY Chemistry is the study of matter, its properties and its changes or transformations. Matter is anything that has mass and takes up space (volume).The chemistry unit is found from pages 135 – 253 in your textbook. Pages 142 – 150 and 184 - 187 in your textbook are a review of grade 9 material. This review will be covered in a handout (9review). Classification of Matter Matter pure substances mixtures heterogeneous mixtures elements compounds solutions An excellent chemistry resource is the text Fundamentals of Chemistry written by Brady and Holum. You are free to sign a textbook out for your enjoyment.

Elements are substances that are found on the periodic table and cannot be broken down into simpler substances (basically). Compounds are substances that are a combination of elements in a fixed proportion. O2, H2O, C6H12O6, C30H62 Solutions (homogeneous mixtures) are a mixture of two or more substances such that only one phase is visible. The mixing is homogeneous to a molecular level. salt water, vodka, apple juice, alloys For liquid solutions a good tip is that if the mixture is clear (could be coloured) then it is a solution. A heterogeneous mixture is a mixture of two or more substances where there is more than one phase visible. The mixing does not take place at a molecular level. Oil and water, sand and water, ice and water, pizza and milk are good examples of these mechanical mixtures.

The Periodic Table The Periodic Table has gone through many forms to its present day arrangement. Today the only changes that are possible for the future are the addition of more elements. There are various levels of organization in the Periodic Table of your textbook. Try and answer these questions to discern this organization. How are gaseous, liquid and solid elements displayed? How are metals, non-metals and metalloids displayed. The highlight of the Periodic Table is the organization of elements in families or groups (vertical columns). These families have similar Lewis Dot diagrams and display similar chemical properties.

Properties of Matter A physical property is a characteristic property of a substance. The substance does not change its identity. state of matter, hardness, odour, solubility, colour. A chemical property is a characteristic behaviour that occurs when a substance changes to a new substance. The change itself is called a chemical change. (In a physical change the substance only changes state.) PEN location charge mass proton nucleus +1 1 u electron orbit -1 0 u neutron nucleus 0 1 u an electron actually weight 1/1876 u but we treat this as 0 u for our purposes

The information about an element is conveyed with following notation. X is the element symbol A is the atomic mass in atomic mass units (u) Z is the atomic number (number of protons) b is the electric charge c is the number of atoms Remember these simple rules for analyzing elements. #p+ + #e- = b #p+ + #no = A -how many pen are there? (neutral!!)

Hydrogen deuterium tritium -only hydrogen has names for its isotopes 6 p+, 4e-, 6no 79 p+, 78e- , 118no 17 p+, 20e- , 20no -try the PEN sheet -the # of p+ determines which element it is

Average Atomic Mass Naturally occurring elements are made up of different isotopes.The mass of an element found on a periodic table is the average atomic mass.It can be calculated by a weighted average of the isotope masses and their percentage natural occurrence. These calculations may not agree exactly with the average atomic mass on the periodic table because the isotope masses above are not exact. When making an atom from protons and neutrons mass is lost in the fusion or fission reaction.

Lewis Dot Diagrams In some ways chemistry can be thought of as how atoms interact with other atoms. The outer shell electrons or valence electrons are the most important part of this interaction.Lewis Dot Diagrams show the valence electrons of an atom. The pattern of valence electrons is the fundamental pattern that determines chemical reactivity. H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar

The fourth period is 18 elements wide however the patterns set up in the second and third rows continue for the rest of the periodic table. The transition metal electrons do enter the outer shell but drop down a level upon leaving the transition metal area.The loss of these ten electrons means that once again the inert gases need eight electrons in their outer shell. Lewis Dot Diagrams are not drawn for transition metal elements. K Ca Ga Ge As Se Br Kr Rb Sr In Sn Sb Te I Xe

Ions An ion is an electrically charged atom or group of atoms. Atoms lose or gain electrons to have a full outer shell. They become isoelectronic with the nearest Noble gas.This full outer shell is a more stable arrangement than the neutral atom. Noble gases do not form ions because they are already quite stable with a full outer shell. Every atom has two choices (full or empty) but the choice which involves gaining or losing the least electrons forms the preferred ion. Hydrogen can lose or gain one electron to become stable (H+ or H-) however the positive hydrogen ion (p+ or H+) is much more common. Carbon and all other members in its group can lose or gain four electrons to become stable, however since this involves so many electrons neither positive or negative ion is common.

Li+ Na+ K+ Rb+ Cs+ Be+2 Mg+2 Ca+2 Sr+2 Ba+2 B+3 Al+3 Ga+3 In+3 Tl+3 F- Cl- Br- I- At- O-2 S-2 Se-2 Te-2 Po-2 N-3 P-3 As-3 Sb-3 Bi-3

IONIC COMPOUNDS Ionic compounds are made up of oppositely charged ions (from a metal and a non-metal). Ionic compounds are also known as salts. Ions are charged particles. An atom or group of atoms (polyatomic) can be an ion. There is an inherent stability to a full octet of electrons. Noble gases have a full outer shell of eight electrons and are so stable they rarely form compounds. Na+ F- Na F NaF Sodium Fluoride opposite charges attract positive first negative second (ending with “ide”) formula unit (not a molecule!) ALL COMPOUNDS ARE NEUTRAL!!

Mg Br Br- Mg+2 Br- B N B+3 N-3 MgBr2 Magnesium Bromide BN Boron Nitride

Al O O-2 O-2 Al+3 Al+3 O-2 Al2O3 Aluminum Oxide Al+3 O-2 Crossing the charges over is an easy way to arrive at the formula unit. Remember to reduce to lowest terms. The goal is always to make a neutral compound. You are expected to draw Lewis Dot Diagrams of ionic compounds as shown. Remember to show the electric charge on the ions. Most times you will be asked to write the formula unit and chemical name only. The Periodic Table tells you the electric charge possible for every element although you shouldn’t need this help since the column location tells you the charge for an element.

State formula of the following compounds. • a) Potassium Sulfide b) Magnesium Iodide • c) Boron Hydride d) Beryllium Phosphide • State the name of the following compounds. • AlF3 b) Na2O c) BaSe d) Cs3N • Draw Lewis Dot Diagrams for (a) of each question answers

The goal of a proper nomenclature system is simplicity and clarity. These requirements mean that you must figure out the formula with a periodic table.This does not sacrifice clarity since there is only one possible compound between a metal and a non-metal. Transition metals (and a few regular metals) are complicated by the fact that some of them have more than one ion possibility. If a transition metal has more than one possible charge the chemical name contains a Roman Numeral to indicate the charge the transition metal possesses. Remember that if a non-metal is negatively charged then it has only one possible charge. • State the formula of each of the following compounds? • Silver Bromide b) Zinc Sulfide • State the name of the following compounds. • CdH2 b) Zn3N2 AgBr ZnS Cadmium Hydride Zinc Nitride

State the formula of each of the following compounds? • Iron (III) Iodide b) Manganese (VII) Oxide • c) Nickel (II) Phosphide d) Gold (I) Bromide • State the name of the following compounds. • PbO2 b) Pt3N2 c) Fe2O5 d) Hg2Cl2 FeI3 Mn2O7 Ni3P2 AuBr Lead (IV) Oxide Platinum (II) Nitride Iron (V) Oxide Mercury (I) Chloride

Before the Stock system (Roman Numerals) a different system for nomenclature of multivalent metal elements was used.An “ous” suffix on the metal indicated a lower charge while an “ic” suffix indicated a higher charge.This system fell out of favour when some metals were found to have more than two possible charges. In addition if an element had a latin based symbol then the latin name of the element had to be used.This system will not be included on any test or quiz. • State the formula of each of the following compounds? • Cuprous Oxide b) Cupric Chloride • c) Ferrous Nitride d) Ferric Iodide • Ferrous Fe+2 Ferric Fe+3 • e) Nicklelous Sulfide f) Nickelic Carbide • State the name of the following compounds. • AuN b) MnO2 c) SnCl4 CuO CuCl2 Fe3N2 FeI3 NiS Ni4C3 Auric Nitride Manganic Oxide Stannic Chloride

Molecular Compounds Ionic compounds form between ions. Positive ions can be metals or polyatomic ions while negative ions can be non-metals or polyatomic ions.Metals and non-metals form ions so they have a full outer shell of electrons. The ions are then bonded to each other because of opposite charges. There is another way to have a full outer shell of electrons and it is accomplished by sharing electrons between two non-metals. Covalent bonds hold atoms together because the two atoms are attracted to a pair of common electrons. This never ending tug of war means the two atoms are linked to each other. The whole situation is energetically stable because each atom senses that it has a full outer shell of electrons. Covalent compounds are always made from non-metals.

H H H H each atom has access to a full outer shell of electrons Lewis dot diagrams H H C H C H H H2 CH4 Don’t show rings on a test

H O H N H Cl Cl H H Cl B Cl Cl H H H H H C C O H H C C H Every atom needs a full outer shell H H H H Try making Lewis dot diagrams for the following molecular compounds. H2O NH3 Cl2 C2H6 C2H6O BCl3

non-bonding electrons H N H H N H bonding electrons H H Drawing Lewis dot diagrams becomes tiresome so we will now move to stick diagrams.Two dots that are involved in bonding are represented by a stick.Electrons that are not involved in bonding are not shown but remember they are present.

try SiH4, Br2, C2NH7, C3NOH9 H H H C C N H H H H H H H H C C C O N H H H H H H H H H H Si H C N C H H H H H H H H H C N O C C H Br Br H H H H

these are not H H H H H C H H C C C O N H H H C H H H H H C O N H H H H H H H C N O C C H these are isomers H H H H Molecular compounds that have the same chemical formula but a different structure are called isomers.

The nomenclature of molecular compounds can be very comp-licated but there is a simple system for molecular compounds that are made up of two kinds of elements. This system of nomenclature uses prefixes to denote the number of atoms in a molecule. The prefixes used are as follows. mono di tri tetra penta hexa hepta octa nona deca CI4 N2O4 P4O10 Carbon Tetraiodide Dinitrogen Tetraoxide Tetraphosphorous Decaoxide Sulfur Hexafluoride Phosphorous Pentachloride Nitrogen Dioxide SF6 PCl5 NO2 A few molecular compound’s names simply must be memorized.Examples of these include water, hydrogen peroxide and ammonia

STICK DRAWINGS Non-metal atoms which make up molecular compounds follow bonding patterns. Carbon, Silicon 4 bonds Nitrogen, Phosphorous 3 bonds Oxygen, Sulfur 2 bonds Hydrogen, Fluorine, Chlorine 1 bond Bromine, Iodine Atoms that can make only one bond are considered “chain enders”. The compounds that will be made on the following pages will have mostly carbon and hydrogen. Carbon forms the backbone or skeleton of many covalent compounds because it can make 4 bonds which allows for infinite variety. The chemistry of carbon is called organic chemistry. Silicon has been proposed as an alternative “life” atom but it is not as suited energetically for the task as carbon.

Non-metal atoms can make up to 3 bonds at once to another atom since it is possible to overlap 3 single electrons at one time. H-C C-H H C H C In the plane of the screen In front of the screen Behind the screen Making a covalent compound means finding an arrangement so that each element has the proper number of sticks.

When given a chemical formula to turn into a stick drawing follow these steps. C3H5NO • Draw the skeleton • (no chain enders). OrCrC-N-C H H H | | | HrOrCrCrNrCrH | | | | H H H H 2. Put in all possible hydrogens. H | HrOrCtCtNrCrH | | H H 3. Remove hydrogens to make final compound.

The general formula for an organic com-pound with no double or triple bonds (or rings) is as follows. CxNyOzH(2x+y+2) (this is not on the test) Phosphorous counts as a nitrogen. Sulfur counts as an oxygen. All chain enders count as hydrogen. Make two different stick drawings for each of the following chemical formulas. C4H4O C6H6 C2H7NO2 C5H7N C3H2O2F2 C4H5SBr Now build the molecules with the kits provided. See which bonds rotate and how the molecule can change shape.

CHEMICAL EQUATIONS The world around us utilizes chemical reactions every day. Chemical reactions or chemical equations show how atoms or molecules change into a new arrangement of atoms or molecules. A common example of a chemical equation is respiration.

glucose + oxygen ----> carbon dioxide + water word equation (simple) C6H12O6(s) + O2(g) ----> CO2(g) + H2O(l) skeleton equation C6H12O6(s) + O2(g) ----> CO2(g) + H2O(l) products reactants to produce to make to yield reacts with combines with solid gas liquid (aq) means aqueous (dissolved in water)

The Law of Conservation of Mass applies to all chemical reactions. It states that in a chemical reaction the total mass of the reactants is always equal to the total mass of the products. Practically this means that matter is not created or destroyed. Chemical reactions change the arrangement of atoms not the number or type of atoms. This means that a proper chemical equation is balanced with regard to the number of atoms on either side of the chemical equation. When balancing chemical equations there are four rules to follow. 1. Only write numbers in front of the chemicals in a reaction. 2. Balance atoms other than oxygen or hydrogen. 3. Balance oxygen or hydrogen. 4. Check. If it is not balanced go back to step 2. The first rule is important so that you do not change the type of molecules present. When applying the third rule it helps to balance the oxygen or hydrogen that is present in only one location on the reactant and product side.

C6H12O6(s) + O2(g) ----> 6CO2(g) + H2O(l) C6H12O6(s) + O2(g) ----> 6CO2(g) + 6H2O(l) C6H12O6(s) + 6O2(g) ----> 6CO2(g) + 6H2O(l) One molecule of solid glucose reacts with six molecules of gaseous oxygen to produce six molecules of gaseous carbon dioxide and six molecules of water. This is an example of a word equation (difficult).

N2+ H2 NH3 N2+ H22NH3 N2+3H22NH3 Mg(NO3)2+ Al2(SO4)3 MgSO4+ Al(NO3)3 3Mg(NO3)2+ Al2(SO4)3 MgSO4+ 2Al(NO3)3 3Mg(NO3)2+Al2(SO4)33MgSO4+ 2Al(NO3)3

C6H14+ O2 CO2+ H2O C6H14+ O26CO2+ H2O C6H14+ O26CO2+7H2O C6H14+9.5O26CO2+7H2O Only whole numbers!! 2C6H14+19O212CO2+14H2O Try balancing these reactions. P + Cl2 PCl5 C4H10 + O2 CO2 + H2O (NH4)3PO4 + Ca(NO3)2  Ca3(PO4)2 + NH4NO3 2 + 5 2 2 +13 8+ 10 2 + 3 1+ 6

TYPES OF CHEMICAL REACTIONS Chemical reactions can be broken down into five types. Synthesis reactions occur when two types of matter combine to form one type of matter. A + B  AB 8Fe + S8 8FeS Decomposition reactions occur when one type of matter breaks down into two or more types of matter. AB A + B2H2O  2H2 + O2

Single Displacement reactions occur when an element is displaced from a compound by another element. A + BC  B + AC Mg + 2AgCl  2Ag + MgCl2 Double Displacement reactions occur when ions or elements are exchanged between compounds. AB + CD  AD + CB Ca(NO3)2 + Na2(CO3)2  CaCO3 + 2NaNO3 Combustion reactions occur when elements or compounds react with oxygen to form oxides. 2Ba + O2  2BaO CH4 + 2O2  CO2 + 2H2O

POLYATOMIC IONS Polyatomic ions are charged groups of atoms that tend to stay together. Ammonium sulfate(NH4)2SO4 is an ionic molecule that is made up of 2 ammonium ions (NH4+) and a sulfate ion (SO4-2). Evidence for ions in a compound is found in a conductivity test.Conductivity of an aqueous solution of the test substance generally confirms the presence of ions in a substance. Polyatomic ions are made up of non-metals that are covalently bonded.demo conductivity When dealing with polyatomic ions treat them as a complicated element (something that cannot be broken down), that you have been given the formula and charge of. Naming molecules with polyatomic ions is similar to naming simple ionic compounds. First comes the positive ion next comes the negative ion. There is no change to the ending of a negative polyatomic ion.

Ammonium hydroxide NH4+ OH- NH4OH Ba+2 NO3- Ca+2 PO4-3 Barium nitrate Ba(NO3)2 Calcium phosphate Ca3(PO4)2 Nickel (III) permanganate MnO4- Ni(MnO4)3 Ni+3 Fe(CO3)3 Iron (VI) carbonate CO3-2 Fe+6 (NH4)2S Al(ClO3)3 Cu3PO4 Zn(OH)2 Au2(SO4)3 Ammonium sulfide Aluminum chlorate Copper (I) phosphate Zinc hydroxide Gold (III) sulfate Show the covalent bonding structure of these polyatomic ions.

Iron (II) Nitrate Aluminum Phosphate Zinc Chlorate Ammonium Carbonate LiOH Mn(CN)7 Ag2CO3 Pt(CrO4)2 Fe(NO3)2 AlPO4 Zn(ClO3)2 (NH4)2CO3 Lithium Hydroxide Manganese (VII) Cyanide Silver Carbonate Platinum (IV) Chromate

FACTORS THAT AFFECT RATES OF REACTION The rate of a chemical reaction is defined as the amount of product formed per unit time. It also can be thought of as the amount of reactant used up per unit time. Chemical reactions occur with a variety of rates. Gasoline is burned quickly in a running car while rusting of a car takes place very slowly. (think of more examples of fast and slow reactions) Kinetic Molecular Theory: A Collision Model Atoms and molecules are in a constant state of motion and collide with each other. Chemical reactions occur when reactants collide with enough energy and proper orientation to cause the chemical change to occur.The chemical change occurs when the chemical bonds of the reactants break and the chemical bonds of the products form. According to this collision model then, there are two ways to increase the rate of reaction.

Increase the number of collisions. • Increase the fraction of collisions that are effective. • The collision model helps us to understand how temperature, concentration, surface area and catalysts affect the rate of reaction. Temperature Temperature (average kinetic energy) is an indication of how fast particles are moving. Increasing temperature increases the number of collisions per unit time which increases the rate of reaction.An increase in temperature also increases the fraction of collisions leading to products because more collisions have the necessary energy to react.An increase of 5o -10o often doubles the rate of reaction. cold blooded, winter, freezers

Concentration Concentration (particles per unit volume) affects the number of collisions between particles. Increased concentration increases the number of collisions which increases the rate of reaction. Surface Area Reactions occur where reactants meet and collide. Increasing surface area increases the rate of reaction by increasing the number of collisions between reactants. (powder, lycopodium) Catalysts A catalyst is a substance that increases the rate of a chemical reaction without being consumed by the reaction. Catalysts work for a variety of reasons. They can bring together the reactants in such a way to ensure perfect orientation or they might lower the energy needed for a reaction to occur. Research of catalysts is important because speeding up reactions saves time or allows a reaction to be utilized for the first time.

CHAPTER EIGHT: ACIDS AND BASES Properties of Acids and Bases Acids are sour-tasting, water-soluble substances that conduct electricity when dissolved in water. They react with many metals to form hydrogen gas. The most important property of acids is that they all produce hydrogen ions (H+) when dissolved in water.

Bases are bitter-tasting water-soluble substances that feel slippery and are good conductors of electricity when in aqueous solution. The most important quality of bases is that they produce hydroxide ions (OH-) when dissolved in water. Bases can also be described as alkaline eg. batteries. Acids and bases are both corrosive but only bases are caustic. tin can demo

Acids and bases are very important substances in our society (tables on pages 293 and 294). Acids vinegar (acetic acid) HC2H3O2(aq) salad dressing citric acid HC6H7O7 (aq) citrus fruit ascorbic acid HC6H7O6 (aq) vitamin C lactic acid HC3H5O3 (aq) sour milk carbonic acid H2CO3 (aq) carbonated drinks acetylsalicylic acid HC9H7O4 (aq) aspirin sulfuric acid H2SO4 (aq) battery acid

Bases sodium hydroxide NaOH(aq) drain cleaner potassium hydroxide KOH(aq) soap, cosmetics aluminum hydroxide Al(OH)3(aq) antacids ammonium hydroxide NH4OH(aq) windex sodium bicarbonate NaHCO3(aq) baking soda potassium sulfite K2SO3(aq) food preservative Read pages 322-323 and answer questions a-h, 1-4. This would form the basis of a good extended response question on a test.

UNIT TWO: CHEMISTRY