Philippine Normal University-ITL National Center for Teacher Education
LESSON PLAN IN SCIENCE 9
FINAL DEMONSTRATION TEACHING November 3, 2014
Hydrocarbons
Anna Reynaline Reynaline D. Mina Mina IV-10 BSE Chemistry Student Teacher
I. Learning Objectives At the end of the lesson, students should be able to: 1.) identify the different classes of hydrocarbons according to their structures 2.) differentiate saturated and unsaturated hydrocarbons 3.) name carbon chains and write chemical structures II. Learning Task A. Subject Matter: Organic Compounds and it’s framework: Hydrocarbons B. Materials: Visual Aids, Activity Sheets C. References: Science & Technology 9 Chemistry, Tenth Edition, Raymond Chang III. Learning Objectives Teacher’s Activities A. Daily Routine Let’s pray first. (Name of Student), please lead the prayer.
Student’s Activities
Student 1: Let us pray. In the name of the Father…Amen Amen
All: Amen
Good Morning Class! Good Morning Ms. Mina. It’s nice to see you. It’s nice to see you too. Say Good Morning to our visitors. Good Morning visitors, Mabuhay! It’s nice to see you. You may now take your seats. Class secretary, please check the attendance. Secretary: Ma’am, only one is absent today. Okay. Thank you. B. Review/Recall Last meeting we discussed about Carbon and what makes it unique. What are those three important characteristics of carbon that enable it to form so many stable carbon compounds? (Students raises their hands)
(Name of Student), give one. Student 2: Carbon has the ability to form story bonds with other carbon atoms to form chains. Okay, correct. Another (Name of Student) Student 3: A carbon atom can form a single, a double or a triple bond with another carbon atom. Right. And last one, (Name of Student). Student 4: A carbon atom can form a double or a triple bond with a non metallic atom. Correct. And what is catenation again class? Student 5: It permits carbon atoms to form over millions of natural and synthetic carbon compounds. C. Motivation I want you to gather with your group mates. Groups are according to the color of your nametags. This game is called “Word Guess” I will hold each flashcard one by one and try to guess what word it is. When you’ve learned the trick, it will be faster for you to guess. Raise your hands when you answer. The group with the highest number of words guessed will receive a prize.
(Each group discusses what to do)
Ready? Yes, Ma’am. 1.) BMLBOFT 2.) DBSCPO 3.) NFUIBOF 4.) CFOAFOF 5.) TBUVSBUFE 6.) EPVCMF 7.) JTPNFSJTN 8.) BMLZM Group (Group number who wins) here’s your prize.
Thank you, Ma’am. D. Lesson Proper Carbon Compounds are also called organic compounds. Hydrocarbons are the framework of all organic compounds. They are compounds made up of hydrogen and carbon. On the main basis of structure. Hydrocarbons are divided into two main classes, Aliphatic and Aromatic. Aliphatic hydrocarbons have straight, branched, or cyclic (ring) chains. Those with single bonds and thus with maximum number of hydrocarbon atoms are Aliphatic Saturated Hydrocarbons. Hydrocarbons with double or triple bonds are Aliphatic Unsaturated Hydrocarbons. Aliphatic Hydrocarbons are divided into alkanes, alkenes, alkynes and cycloalkanes. While Aromatic Hydrocarbons are those hydrocarbons with benzene rings. These rings are cyclic chains with six carbon atoms that form into hexagons. Now, let’s discuss about Aliphatic Saturated Hydrocarbons. Alkanes are aliphatic saturated hydrocarbons. They have the general formula CnH2n+2, where n, which represents the number of carbon atoms, is equal to 1, 2, 3,… Alkanes may have straight or branched chains. We’ll discuss those two later as we go on with our discussion. Methane (CH4), is the first member of the alkanes. The next member of this series is ethane (C 2H6), followed by propane (C3H8) and then butane (C 4H10). Straight-chain alkanes can be built out of any number of carbon atoms by tacking carbon atoms together in a straight chain
and sufficiently adding hydrogen atoms to satisfy the four bonds surrounding each carbon atom. In naming straight-chain alkanes, we follow a pattern. Their names have two parts: a prefix that shows the number of carbon atoms and the suffix –ane, which indicates that the hydrocarbon is saturated. The prefixes are meth, eth, prop, but, pent, hex, hept, oct, non and so on. For example propane (C 3H8) has three carbon atoms. Its prefix is propand its suffix –ane. Thus C 3H8 has the name prop + ane = propane. Naming branched-chain alkanes is through considering them as straightchain alkanes with attached side groups. For example, consider the following branched-chain alkane: 4
3
2
1
CH3-CH2- CH2- CH3
butane (parent chain)
CH3
methyl (side group)
The longest carbon chain or parent chain of the sample alkane had four C atoms. The parent chain is thus regarded as butane. It has –CH3 attached as the side group to the second C atom. The side group – CH3 is methyl, which is just methane with one H atom removed. It is therefore called 2-methylbutane. A side group composed of single-bonded carbon and hygrogen atoms is called an alkyl group and is represented by the letter R. There are rules to consider in naming a branched-chain alkane. First look for the parent chain in the
structure. Remember that a parent chain has the longest carbon chain. Find the side group attached to the parent chain. Name the parent chain and the side group. Number the carbon atoms in the parent chain, starting from the one nearest to the carbon where the side group is attached. Cycloalkanes are Aliphatic Saturated Hydrocarbons with rings. The general formula of cycloalkanes C nH2n. They behave similarly to straight-chain alkanes except for the use of the prefix cyclo-. Cycloalkanes experience angular strain on the C-C bonds. So, cycloalkanes are unstable, reactive and easily open up to straight-chain hydrocarbons. The stability of cycloalkanes increases as the number of carbon atoms increases. Cyclopropane with three carbon atoms is the least stable cycloalkane. Now, let’s move on to the Aliphatic Unsaturated Hydrocarbons, the Alkenes and Alkynes. Alkenes are aliphatic hydrocarbons with one or more double bonds between carbon atoms. They are represented by the formula C nH2n. Alkynes, on the other hand, are aliphatic hydrocarbons with triple bonds between carbon atoms. They are represented by the genral formula C nH2n-2. The simplest alkyne is ethyne, commonly known as acetylene. Its structure is CH CH. Alkenes and Alkynes are named using the general rules for alkanes but using the suffixes –ene and –yne insteas of – ane. And also, a number is used to indicate the position of the double bond and triple bond in the molecule.
1
2
3
4
For example, CH 3CH=CHCH3 is named 2-butene. The double bond is in between Carbon 2 and Carbon 3, but 2 is used for the name because it is lower. Now, before we proceed to the Aromatic hydrocarbons, let’s have an activity about what we have discussed. Gather with your groupmates, and leaders will come and get your materials. We’ll have a short quiz bee. I have Eight Questions and you will be given 30 seconds to answer each question. I’ll repeat the question only once so listen carefully. You can only start answering when I say go. The group with the highest score will be given additional points on the quiz. Okay, are you ready? 1. Draw the structure of the alkene that contains 6 carbons and has a double bond between carbon 3 and 4. Go. Time’s up. Raise your boards. The answer is
2. Name the alkene from question number 1. Number your chain first. Go. Time’s up. Raise your boards. The answer is 3-hexene 3. Which of the following hydrocarbons fit the general formula C nH2n-2? a. propane b. butyne c. hexene Go.
Time’s up. Raise your boards. The answer is B. 4. Which of the following is unsaturated? a. cyclohexane b. octane c. heptene Go. Time’s up. Raise your boards. The answer is C. 5. What is the correct name for CH3CH(CH3)CH2CH3? a. 4-methylbutane b. Cyclopropane c. 2-methylbutane Go. Time’s up. Raise your boards. The answer is C. 6. Name this structure
Go. Time’s up. Raise your boards. The answer is Propene. 7. What do you call the side group that contains single bond? Go. Time’s up. Raise your boards. The answer is Alkyl Group 8. This hydrocarbon is unstable and reactive. Go. Time’s up. Raise your boards. The answer is Cycloalkanes Okay, now let’s move on to Aromatic Hydrocarbons.
Benzene is the parent compound of aromatic hydrocarbons and the simplest form of this class. It is a ring of six carbon atom, each attached to one hydrogen atom. The structure of benzene can be represented into three:
Aromatic Hydrocarbons with more than one ring are called polycyclic aromatic hydrocarbons or fused-ring compounds. E. Generalization Now, let’s see if you’ve learned something from our discussion. I have strips of papers here with the things we have discussed. On the concept map, I would like you to put the words on their position. This is the concept map: HYDROCARBON
Aliphati
Aromatic
Alkanes Cycloalkanes Alkenes Alkynes
Okay, very good. F. Assessment Now let’s have a short quiz. The questions are posted on the board
1. Organic chemistry is the study of compounds containing: a. Hydrogen b. Sulfur c. Carbon
2. What is the formula for benzene? a. C6H6 b. C6H7 c. C6H5 3. Aromatic Hydrocarbon with more than one ring are called 4. Aliphatic hydrocarbons are divided into four what are those? 5. Draw two representations of benzene. After 5mins. Okay pass your papers. Let’s Check.
1. C 2. A 3. Fused-ring compound or polycyclic aromatic hydrocarbon. 4. Alkanes, alkenes, alkynes, cycloalkanes 5. (two of this three)
G. Assignment: Now, take note of your assignment. 1. Give the properties and uses of hydrocarbons 2. What is a functional group? Give atleast 8 functional group. Write your answers on an intermmediate pad. Are you done? Yes, Maam Then that’s all for today. Goodbye Class. Good bye and thank you Ms. Mina
