OTHER MOLECULAR COMPOUNDS (Hydrocarbons) *write down what is in blue

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William Parks
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1 OTHER MOLECULAR COMPOUNDS (Hydrocarbons) *write down what is in blue

Compounds can be categorized into two groups

2 Compounds can be categorized into two groups Inorganic Compounds: compounds lacking carbon atoms. Ex. minerals, rocks etc. Organic Compounds: compounds that are based on carbon. They usually contain carbon- carbon and carbon- hydrogen bonds. Ex. they make up your hair, skin, ﬁngernails, etc

3 Why is Carbon So Special? Carbon can form 4 bonds with 4 different molecules.

4 Simple Organic Compounds Called! HYDROCARBONS Made of carbons and hydrogens The first class of simple hydrocarbons are called ALKANES Structure: contain only C C single bonds Naming: a prefix describes the number of carbon atoms followed by the ending "ane". (formula is C n H 2n+2 ) Uses: Alkanes are flammable and make good fuels

5 Carbon Atoms Prefix Name Formula Meth Methane CH 4 Eth Ethane C 2 H 6 Prop Propane C 3 H 8 But Butane C 4 H 10 Pent Pentane C 5 H 12 Hex Hexane C 6 H 14 Hept Heptane C 7 H 16 Oct Octane C 8 H 18 Non Nonane C 9 H 20 Dec Decane C 10 H 22

6 Your First Chemical Reaction This Year! The COMBUSTION of methane Let s See It!!!

of Chemical Reactions There are 6 main signs

place: change in color change in odor production

7 What is a CHEMICAL REACTION? It is a process in which a new substance with new propernes is formed. Ex. burning wood, cooking food, iron rusnng, Signs of Chemical Reactions There are 6 main signs that indicate a chemical reacnon has taken place: change in color change in odor production of new gases or vapor production of light or heat formation of a precipitate difficult to reverse

8 Chemical Equations! and! Conservation of Mass

REACTANTS PRODUCTS + (with some heat) MAKES Reactants the substances that exist before

9 Chemical Equation a representanon of what happens to reactants and products during a chemical change I m hungry - how about a sandwich equation? REACTANTS PRODUCTS + (with some heat) MAKES Reactants the substances that exist before a chemical change (or reacnon) takes place. Products the new substance(s) that are formed during a chemical change.

10 Skeleton Word Equations provides describes information a chemical about change the using reactants the names and products of the of the reactants reaction and products. Write Write the the word skeleton equation equation for the for combustion the reaction reaction methane + oxygen carbon dioxide + water Reactants Products CH O 2 CO H 2 O (g) (g) (g) (g) The lerers (s), (l), (g) and (aq) are the physical states of compounds. The numbers in the front are called stoichiometric coefficients.

11 Let s Try Making and Balancing the Chemical Equation with Molecular Model Kits CH O 2 CO H 2 O (g) (g) (g) (g)

12 Antoine Lavoisier Antoine Lavoisier and his wife in 1788 WHO: French Chemist WHEN: Late 1700 s WHAT: Performed experiments where he measured the mass of the products and then the mass of the reactants and found they were the same! LAW OF CONSERVATION OF MASS In a chemical reaction the total mass of the products is equal to the total mass of reactants. The amount of matter in a system does not change.

13 Balancing Chemical Equations Balanced Equation: one in which the number of atoms of each element in the reactants is equal to the number of atoms of each element in the products. Note: Stoichiometric Coefficients are used to balance the equanons! Determine whether the following equation is balanced. 2 Na + H 2 O à 2 NaOH + H 2 2 Na + 2 H 2 O à 2 NaOH + H 2

14 Visualizing a Chemical Reaction 2 Na Na 10 Na atoms 5 2 molecules 10 Na compounds Let s add Stoichiometric Coefficients!

15 Visualizing a Chemical Reaction 2 Na Na

16 Unbalanced and Balanced Equations Because of the principle of the conservanon of marer, an equaion must be balanced. (It must have the same number of atoms of the same kind on both sides). H H H H H H H H à H H reactants 2 2 (unbalanced) products 1 1 H H à 2 H reactants products (balanced)

17 Steps for: Writing and Balancing Chemical Equations 1. Write a word equation for the reaction. 2. Write the correct formulas for all reactants and products. 3. Determine the coefficients to balance the equation (use a chart to help you out). Tip 1: balance compounds first and elements last Tip 2: balance hydrogen and oxygen last Tip 3: if a polyatomic ion appears in both the reactant and product think of it as a single unit. Tip 4: do a final check by counting the atoms on each side Tip 5: if you go back and forth between 2 substances using higher and higher coefficients, double-check each chemical formula.

18 Ex 1. Write a balanced equation for the reaction between chlorine and sodium bromide to produce bromine and sodium chloride. 1) Write a word equation for the reaction. chlorine + sodium bromide à bromine + sodium chloride 2) Write the correct formulas for all reactants and products. 2 + NaBr à Br 2 + Na 3) Determine the coefficients that make the equation balance. 2 + NaBr à Br 2 + Na 2 2 ATOMS Na Br Reactants Products BALANCED!

19 Ex 2. Write the balanced equation for the following word equation.?? aluminum sulfate + calcium chloride à calcium sulfate + aluminum chloride 2) Write the correct formulas for all reactants and products. Al 2 (SO 4 ) 3 + Ca 2 à CaSO 4 + Al 3 3) Determine the coefficients that make the equation balance. Al 2 (SO 4 ) Ca 2 à 3 CaSO Al 3 ATOMS Al SO 4 Ca Reactants Products BALANCED!

20 Additional Symbols Used in Chemical Equations Yields ; indicates result of reaction Used to indicate a reversible reaction (s) (l) (aq) (g) A reactant or product in the solid state; also used to indicate a precipitate A reactant or product in the liquid state A reactant or product in an aqueous solution (dissolved in water) A reactant or product in the gaseous state

Chemical Reactions. Chemical changes are occurring around us all the time

Chemical Reactions. Chemical changes are occurring around us all the time Chemical changes are occurring around us all the time Food cooking Fuel being burned in a car s engine Oxygen being used in the human body The starting materials are called reactants The ending materials