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Notebook set-up. Composition Book. Table of contents. Page. 1. Stoichiometry. 1. Stoichiometry. Standard 3 Ms. Siddall. Stoichiometry. 1. The periodic table. The periodic table displays all elements Symbols on the left represent metals
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Notebook set-up Composition Book
Table of contents Page 1 Stoichiometry
Stoichiometry. Standard 3 Ms. Siddall
The periodic table • The periodic table displays all elements • Symbols on the left represent metals • Symbols on the right represent non-metals Non-metals metals Separation line
The periodic Table • The periodic table displays all elements • Symbols on the left represent metals • Symbols on the right represent non-metals 3 2
Summary 1 • Identify the following elements as metals or non-metals: • Copper • Chlorine • Carbon • Sodium • Calcium • Hydrogen
The periodic Table • The periodic table displays all elements • Symbols on the left represent metals • Symbols on the right represent non-metals Summary 1: Identify the following elements as metals or non-metals 2 3
Symbols • Each chemical symbol on the periodic table represents an element • chlorine = Cl • sodium = Na • Symbols written together represent a compound • NaCl = a sodium atom combined with a chlorine atom
The periodic Table • The periodic table displays all elements • Symbols on the left represent metals • Symbols on the right represent non-metals Summary 1: Identify the following elements as metals or non-metals symbols Summary 2: • Each chemical symbol on the periodic table represents an element • chlorine = Cl 2 3
Notes… Summaries… 4 5
Summary 2 • Define the following words • Element: • Atom: • Compound: • Chemical formula: • Describe the similarities and differences between an atom and an element
Compounds • Covalent compound: non-metal atoms combine to form molecules • e.x. H2O and CO2 • Ionic compound: metal and non-metal atoms combine to form formula units • e.x. NaCl, CuSO4 • chemical formula: a combination of symbols and numbers that describe the amount and type and of atoms that form a compound.
Summary 3 • Identify the following compounds as ionic or covalent • CuSO4 • NaCl • CO2 • H2O
Anatomy of a chemical formula CuSO4(aq) Atomic symbols describe the type of atoms in the compound (copper, sulfur, oxygen) subscript numbers describe the number of atoms in the compound (1 copper, 1 sulfur, 4 oxygen) subscript letters describe the physical state of the compound (aqueous)
Summary 4 Na2O(s) In the above formula: • How many sodium atoms? • How many oxygen atoms? • What is the physical state? • Is the compound ionic or covalent?
Standard 3a: describing chemical reactions An equation describes a chemical reaction or a physical change • Reactants: chemicals that react • Products: chemicals that are formed • e.x. sodium + oxygen sodium oxide Na(s) + O2(g) Na2O(s) reactants product
Summary 5 Pb(NO3)3(aq) + KI(aq) KNO3(aq) + PbI3(s) • Label the reactants and the products in the reaction above • Are the reactants and products covalent or ionic? • How many oxygen atoms are in the compound Pb(NO3)3?
Symbols describing chemical reactions Copy table 11.1 (page 323)
Summary 6 • What do the following symbols mean? • (l) • (aq) • • Pb(NO3)3(aq) + KI(aq) KNO3(aq) + PbI3(s) • Which compound is solid?
Balancing chemical equations The Law of Conservation of Matter:Matter cannot be created or destroyed. • For chemical equations: The total number of each type of atom must be the same before and after the reaction Thou shall not create or destroy matter
example • Sodium reacts with oxygen to produce sodium oxide • How many sodium atoms react? • How many sodium atoms are in the product? • This violates the law of conservation of matter! Na(s) + O2(g) Na2O(s) 1 2
Summary 7 NaI(s) + Cl2(g) NaCl(s) + I2(s) • Count the number of atoms on the reactants side • Sodium ____ • Iodine ____ • Chlorine ____ • Count the number of atoms on the products side • Sodium ____ • Iodine ____ • Chlorine ____ Does this equation obey the law of conservation of matter?
Example: Na(s) + O2(g) Na2O(s) 4 2 • Coefficients are used to balance the equation • number of atoms or formulas needed in the reaction. These apply to the entire formula (all the atoms) • 4Na = 4 sodium atoms • 2Na2O = 4 sodium atoms and 2 oxygen atoms SUBSCRIPTS CAN NOT CHANGE!
Summary 8 2Cu(s) + O2(g) 2CuO(s) • Count the number of atoms on the reactants side • copper ____ • Oxygen ____ • Count the number of atoms on the products side • copper ____ • Oxygen ____ Does this equation obey the law of conservation of matter?
Rules of Balancing Equations • Write the equation using correct formulas. You may NOT change the formula in any way. • Balance the equation using coefficients
Balancing example: sodium and oxygen react to form sodium oxide Take atomic inventory: (you mustobey the Law of Conservation of Matter) Na + O2 Na2O Reactants: Products: Na O Na O 1 2 2 1 Problem: begin with 2 oxygen atoms but end with only 1 This breaks the law of conservation of matter.
Na + O2 Na2O 2 (= Na2O + Na2O) solution: Add the coefficient ‘2’ in front of Na2O Take atomic inventory again: Reactants: Products: Na O Na O 1 2 4 2 Problem: begin with 1 sodium atom but end with 4. This breaks the law of conservation of matter.
4 Na + O2 2Na2O solution: Add the coefficient ‘4’ in front of Na Take atomic inventory again: Reactants: Products: Na O Na O 4 2 4 2 4 sodium atoms combine with 1 oxygen molecule to form 2 formula units of sodium oxide. This equation obeys the Law of Conservation of Matter.
Summary 9 • BALANCE THE FOLLOWING REACTION: H2(g) + O2(g) H2O(l)
Weird things: polyatomic ions • Ionic compounds can be formed with polyatomic ions (made from many atoms) • CO32- = one carbon and three oxygen atoms • SO42- • OH- • NH4+ • Sometimes you can treat a polyatomic ion like one atom sometimes you must balance individual atoms
Summary 10 • Identify the polyatomic ions in the following compounds: • CO2 • KNO3 • NaOH • CuCl2 • Li3PO4 • NH4OH
Balancing with polyatomic ions • Sometimes polyatomic ions break apart in a chemical reaction and sometimes they do not • e.x. sulfate appears on both sides of the reaction so SO4 can be treated like one atom: Mg(s) + CuSO4(aq) MgSO4(aq) + Cu(s) • e.x. carbonate breaks apart so atoms must be balanced individually: CaCO3(aq) + HCl(aq) CaCl2(aq) + H2O(l) + CO2(g)
Summary 11 • Balance the following equations: • Na2CO3(s) + HCl(aq) NaCl(aq) + CO2(g) + H2O(l) • K2SO4(aq) + CaCl2(aq) CaSO4(s) + KCl(l)
Types of Chemical Reactions. 1. Combination. • Also called synthesis • Two or more reactants combine to form one product • e.x. 2 Na(s) + Cl2(g) 2 NaCl(s) • A + B AB http://chemed.chem.purdue.edu/demos/main_pages/7.1.html
Summary 12 Which equation represents a synthesis reaction? • 2Ca(s) + O2(g) 2CaO(s) • 2KClO3(s) 2KCl(s) +O2(g)
2. Decomposition. • One reactant decomposes to form two or more products. • 2H2O(l) 2H2(g) + O2(g) • AB A + B
Summary 13 Which equation represents a decomposition reaction? • Ca(s) + O2(g) CaO(s) • 2KClO3(s) 2KCl(s) +O2(g)
3. Single Replacement. • An atom replaces an ion in a compound. • Mg(s) + CuSO4(aq) MgSO4(aq) + Cu(s) • Cl2(g) + 2KI(aq) I2(s) + 2KCl(aq) • A + BC AC + B
Summary 14 Which equation represents a single replacement reaction? • 2NaI(s) + Cl2(g) 2NaCl(s) + I2(s) • 2NaI(aq) + Pb(NO3)2(aq) 2NaNO3(aq) + PbI2(s)
4. Double Replacement. • Ions from different compounds switch places. • CaCO3(s) + 2HCl(aq) CaCl2(s) + H2CO3(aq) • AB + CD AD + CB
Summary 15 Which equation represents a double replacement reaction? • 2NaI(s) + Cl2(g) 2NaCl(s) + I2(s) • 2NaI(aq) + Pb(NO3)2(aq) 2NaNO3(aq) + PbI2(s)
5. Combustion reactions. • A compound reacts with oxygen • often produces CO2 & H2O • e.x. C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g)
Summary 16 • Write the balanced equation for the reaction of CO with O2 to form CO2 and identify the type of reaction.
Standard 3e:The Arithmetic of Equations. • A balanced equation shows the amount of each reactant and product needed or produced in any reaction.
Example. • Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g) • One atom of magnesium combines with 2 formula units of HCl to form one formula unit of magnesium chloride and one molecule of hydrogen gas. • Use equation coefficients to solve quantitative problems.
Summary 17 4Na(s) + O2(g) 2Na2O(s) • How many molecules of oxygen are needed to react with 4 atoms of sodium? • How many oxygen atoms is that? • How many formula units of sodium oxide are produced when 4 atoms of sodium are used?
Example. • Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g) • If 1 atom of magnesium is used, 2 formula units of HCl are needed to react. • If 6 atoms of magnesium are used, how many formula units of HCl are needed? 6 atom Mg Fo.U. HCl 2 Fo.U. HCl 12 = 1 atom Mg
Anatomy of a conversion T-Chart: multiply everything on top and divide by everything on the bottom Units for answer Given(units) = answer Units of given What you know What you get Conversion factor