Transport announcements
Listen to some transport announcements to practise and improve your listening skills.
Do the preparation task first. Then listen to the audio and do the exercises.
Preparation
See MoreListening A2: Transport announcements – preparation
Match the definitions with the words in CAPITAL letters in the sentences.
Transcript
See MoreA
The next train to arrive at Platform 2 is the 12.20 to Bristol Temple Meads, calling at Reading, Oxford and Bristol Parkway. Platform 2 for the 12.20 to Bristol. First class is in the rear carriage.
B
This is a platform announcement for passengers for the 12.20 service to Bristol Temple Meads. This train is delayed by approximately 8 minutes. The train will now depart from Platform 9. Passengers for the 12.20 train to Bristol, please make your way to Platform 9.
C
Passengers for Flight EB380 to Paris please make your way to Gate 13 for boarding. Gate 13 for flight EB380 to Paris. Please have your passports and boarding passes ready. Your flight is ready to board.
D
This is a London Underground service to Liverpool Street. The next station is Liverpool Street. Upon arrival, the first set of doors will not open. Customers in the first carriage, please move towards the rear doors to leave the train. The next station is Liverpool Street. Change here for Central Line, Circle Line, Hammersmith & City Line and Metropolitan Line and Main Line Suburban rail services. Please mind the gap between the train and the platform. This train terminates at Redbridge.
Task 1
See MoreListening A2: Transport announcements – 1
Are the sentences true or false?
Task 2
See MoreListening A2: Transport announcements – 2
Match the numbers with the information.
Missing a class
Listen to a student explain why she can’t come to class to practise and improve your listening skills.
Do the preparation task first. Then listen to the audio and do the exercises.
Preparation
See MoreListening A2: Missing a class – preparation
Complete the phrases with the words.
Transcript
See MoreStudent: Excuse me, Ms Henderson?
Teacher: Yes, Diana. How can I help you?
Student: I’m sorry, but I can’t come to class next Wednesday. I have a doctor’s appointment.
Teacher: OK. Thanks for letting me know.
Student: Is there anything to do at home?
Teacher: Let me just check my notebook. OK, first of all … you need to read chapters 17, 19 and 20 in the book. There are also some articles and a video to watch – those are online. I’ll post the links online in the usual place.
Student: Chapters 17 to 20.
Teacher: Yes, except chapter 18. Chapters 17, 19 and 20.
Student: Ah, OK. Um … is there a deadline?
Teacher: Yes, this Friday. But there’s something else. I was going to give you all a practice test.
Student: A practice test?
Teacher: Yes, to help people prepare for the mid-term exam.
Student: Ah. All right.
Teacher: Don’t worry, I can send you the practice test by email on Wednesday. Can you send it to me before Friday?
Student: Sure, no problem.
Teacher: And don’t forget to bring a certificate from the doctor to the office.
Student: Thanks, Ms Henderson! I’ll do that.
Teacher: You’re welcome, Diana. Take care.
Task 1
See MoreTask 2
See MoreListening A2: Missing a class – 2
Put the words in order to make sentences.
The first English class
Listen to a teacher give students information about a new course to practise and improve your listening skills.
Do the preparation task first. Then listen to the audio and do the exercises.
Preparation
See MoreListening A1: The first English class – preparation
Put the words in the correct order.
Transcript
See MoreHello, everyone. Hello! It’s nice to see you all here. Welcome to British Life and Language. I am your teacher. My name is Lindsay Black. That’s L-I-N-D-S-A-Y Black. Before we begin, some information about the class.
Our class is in room 13, on the first floor. When you go upstairs, turn left to find the room. Again, that’s room 13.
We have class twice a week, on Monday and Wednesday. Our class begins at 4.30 p.m. and lasts 90 minutes, so we finish at 6 p.m. That’s 4.30 to 6. Please arrive on time, OK?
Also, I have an office hour if you have questions. I’m in office 7B on the second floor. My office hour is Friday at 6 p.m. So, if you have any questions or problems or want to talk to me, it’s Friday at 6 p.m. in office 7B.
We begin next week, on March the 13th. That’s Monday, March the 13th. The course ends on May the 20th. May the 20th is the last day.
I think that’s all … Oh, one more thing. For this course you need the book. Here it is: British Life and Language Level 1 Student’s Book. So, please get a copy of the book. I don’t want to see any photocopies of the book, thank you! Remember, it’s level 1 student’s book. Don’t buy the teacher’s book.
I think that’s all, everyone. I look forward to working with you. See you next Monday!
Task 1
See MoreListening A1: The first English class – 1
Are the sentences true or false?
Task 2
See MoreShopping for clothes
Listen to a conversation in a shop to practise and improve your listening skills.
Do the preparation task first. Then listen to the audio and do the exercises.
Preparation
See MoreListening A1: Shopping for clothes – preparation
Transcript
See MoreShop assistant: Hello, can I help you?
Customer: I’m just looking, thanks.
Customer: Excuse me?
Shop assistant: Yes?
Customer: Where are the changing rooms?
Shop assistant: They’re over there. Behind you.
Customer: Thank you.
Customer: Hi. Excuse me again. Do you have this jumper in black?
Shop assistant: Yes, just a moment. What size do you need?
Customer: Extra small, please.
Shop assistant: Here you are.
Customer: How much is this?
Shop assistant: It’s £29.
Customer: Can I pay by credit card?
Shop assistant: Yes, you can. Of course.
Shop assistant: Would you like a bag for that?
Customer: Yes, please.
Task 1
See MoreListening A1: Shopping for clothes – 1
Put the questions in the order that you hear them.
Task 2
See MoreListening A1: Shopping for clothes – 2
Match the answers with the questions.
Organising a group project
Listen to people organising a group project and answer the questions to practise and improve your listening skills.
Do the preparation task first. Then listen to the audio and do the exercises.
Preparation
See MoreListening A1: Organising a group project – preparation
Match the times with the words.
Transcript
See MoreCara: So for our group project, do you want to start this week?
Selim: Yeah, I want to start early so we have enough time.
Robert: Me too, but I’ve got a big maths project too.
Cara: How about we meet first to plan what we’re going to do? Just for an hour.
Robert: Good idea, Cara.
Cara: When are you free?
Robert: I can always do mornings before 10.
Cara: Robert … Uh …
Selim: I’m sleeping before 10!
Robert: OK! OK, so when are you two free?
Cara: Wednesdays are good for me. But not very early, please!
Selim: I can’t do the mornings on Wednesdays but I have 3 till 5 free.
Robert: I can do 4 o’clock, just before my maths class.
Cara: Great, 4 then. Where shall we meet?
Selim: The library?
Robert: I don’t know. The library isn’t a good place for a planning meeting as we can’t talk in there.
Cara: How about the university café? It’s near the library. We can talk in there. And eat cake.
Selim: Cake is good.
Robert: OK, so Wednesday at the café. I need to leave at ten to five to go to my maths class.
Cara: No problem. Planning will take less than an hour.
Selim: OK! See you Wednesday for cake.
Robert and Cara: See you, Selim!
Task 1
See MoreListening A1: Organising a group project – 1
Are the sentences true or false?
Task 2
See MoreListening A1: Organising a group project – 2
Match the phrases that mean the same thing.
testing
?
Ordering in a café
Listen to people ordering food and drinks in a café to practise and improve your listening skills.
Do the preparation task first. Then listen to the audio and do the exercises.
Preparation
See MoreListening A1: Ordering in a café – preparation
Put the words in the correct group.
Transcript
See MoreCustomer 1: Can I have an orange juice, please?
Server: Regular or large?
Customer 1: How big is a large?
Server: This is a large. This is a regular.
Customer 1: I’ll have a large, then, please. Without ice.
Server: OK, coming up.
Customer 1: Sorry, I wanted freshly squeezed orange juice.
Server: I’m afraid we only have bottled juices.
Customer 1: Oh, then I’ll have an apple juice instead, please.
Server: Here you go. That’s £3.50, please.
Customer: Thanks.
Server: Thank you.
Server: Can I help anyone?
Customer 2: Who’s next?
Customer 3: You were first, I think.
Customer 2: What teas do you have?
Server: Breakfast tea, mint and green tea.
Customer 2: A mint tea and a slice of lemon cake, please.
Server: To eat in or take away?
Customer 2: Take away, please.
Server: There you go. That’ll be £4.20, please.
Customer 2: Sorry, I’ve only got a fifty.
Server: That’s OK. Here’s your change … 5, 10, 30, 50.
Server: Who’s next?
Customer 4: Can I have a …
Customer 3: Sorry, I think I was in front of you.
Customer 4: Oh, sorry!
Customer 3: Can I have a chocolate chip cookie, please?
Server: Would you like a drink with that?
Customer 3: No, thanks. Just the cookie.
Server: OK, then. That’s 95p, please.
Customer 3: Thanks. I think that’s right.
Server: 50, 70, 80, 85, 90, 92, 94, yep, 95. Thank you.
Task 1
See MoreTask 2
See MoreMeeting people at a dinner
Listen to introductions at a dinner party to practise and improve your listening skills.
Do the preparation task first. Then listen to the audio and do the exercises.
Preparation
See moreListening A1: Meeting people at a dinner – preparation
Choose the TWO correct answers. One answer is not correct.
Transcript
See moreCharles: Hello, Julian.
Julian: Hello, Charles. How are you?
Charles: I’m fine. Fine. Julian, do you remember Alyssa?
Julian: No, I don’t.
Charles: She’s Ben’s sister. Do you remember? We were all at Ben’s wedding together.
Julian: Ah, yes, I do – in that old castle. Was it in January?
Charles: Yes, it was! Alyssa was there.
Alyssa: Hello. Nice to meet you … again.
Julian: Hello, nice to meet you too, Alison.
Alyssa: I’m not Alison.
Julian: What?
Alyssa: My name isn’t Alison. It’s Alyssa.
Julian: I’m sorry. Nice to meet you, Alyssa.
Charles: Good. Would you like a drink?
Julian: Good idea.
Alyssa: Yes, please.
Charles: Here you are.
Alyssa and Julian: Thanks!
Task 1
See moreListening A1: Meeting people at a dinner – 1
Put the sentences in the order that you hear them.
Task 2
See moreListening A1: Meeting people at a dinner – 2
Are the sentences true or false?
Hydrocarbons
In this section, you will review the structure and names of hydrocarbons. As you may recall from your previous chemistry studies, hydrocarbons are the simplest type of organic compound. Hydrocarbons are composed
entirely of carbon and hydrogen atoms, and are widely used as fuels. Gasoline, propane, and natural gas are common examples of hydrocarbons. Because they contain only carbon and hydrogen atoms, hydrocarbons are
non-polar compounds.
Scientists classify hydrocarbons as either aliphatic or aromatic. An aliphatic hydrocarbon contains carbon atoms that are bonded in one or more chains and rings. The carbon atoms have single, double, or triple bonds. Aliphatic hydrocarbons include straight chain and cyclic alkanes, alkenes, and alkynes. An aromatic hydrocarbon is a hydrocarbon based on the aromatic benzene group. You will encouter this group later in the section. Benzene is the simplest aromatic compound. Its bonding arrangement results in special molecular stability.
Alkanes, Alkenes, and Alkynes
An alkane is a hydrocarbon that has only single bonds. Alkanes that do not contain rings have the formula CnH2n + 2. An alkane in the shape of a ring is called a cycloalkane. Cycloalkanes have the formula CnH2n. An alkene is a compound that has at least one double bond. Straight-chain alkenes with one double bond have the same formula as cycloalkanes, CnH2n. A double bond involves two pairs of electrons. In a double bond, one pair of electrons forms a single bond and the other pair forms an additional, weaker bond. The electrons in the additional, weaker bond react faster than the electrons in the single bond. Thus, carbon-carbon double bonds are more reactive than carbon-carbon single bonds. When an alkene reacts, the reaction almost always occurs at the site of the double bond.
A functional group is a reactive group of bonded atoms that appears in all the members of a chemical family. Each functional group reacts in a characteristic way. Thus, functional groups help to determine the physical and chemical properties of compounds. For example, the reactive double bond is the functional group for an alkene. In this course, you will encounter many different functional groups. An alkyne is a compound that has at least one triple bond. A straightchain alkyne with one triple bond has the formula CnH2n – 2. Triple bonds are even more reactive than double bonds. The functional group for an alkyne is the triple bond.
Figure 1.7 gives examples of an alkane, a cycloalkane, an alkene, and an alkyne.
General Rules for Naming Organic Compounds
The International Union of Pure and Applied Chemistry (IUPAC) has set standard rules for naming organic compounds. The systematic (or IUPAC) names of alkanes and most other organic compounds follow the same pattern, shown below.
The Root: How Long Is the Main Chain?
The root of a compound’s name indicates the number of carbon atoms in the main (parent) chain or ring. Table 1.2 gives the roots for hydrocarbon chains that are up to ten carbons long. To determine which root to use, count the carbons in the main chain, or main ring, of the compound. If the compound is an alkene or alkyne, the main chain or ring must include the multiple bond.
The Suffix: What Family Does the Compound Belong To?
The suffix indicates the type of compound, according to the functional groups present. (See Table 1.4 on page 22.) As you progress through this chapter, you will learn the suffixes for different chemical families. In your previous chemistry course, you learned the suffixes -ane for alkanes, -ene for alkenes, and -yne for alkynes. Thus, an alkane composed of six carbon atoms in a chain is called hexane. An alkene with three carbons is called propene.
The Prefix: What Is Attached to the Main Chain?
The prefix indicates the name and location of each branch and functional group on the main carbon chain. Most organic compounds have branches, called alkyl groups, attached to the main chain. An alkyl group is obtained
by removing one hydrogen atom from an alkane. To name an alkyl group, change the -ane suffix to -yl. For example, CH3 is the alkyl group that is derived from methane, CH4. It is called the methyl group, taken from the root meth-. Table 1.3 gives the names of the most common alkyl groups.
Read the steps below to review how to name hydrocarbons. Then examine the two Sample Problems that follow.
How to Name Hydrocarbons
| Step_1 | Find the root: Identify the longest chain or ring in the hydrocarbon. If the hydrocarbon is an alkene or an alkyne, make sure that you include any multiple bonds in the main chain. Remember that the chain does not have to be in a straight line. Count the number of carbon atoms in the main chain to obtain the root. If it is a cyclic compound, add the prefix -cyclo- before the root. |
| Step_2 | Find the suffix: If the hydrocarbon is an alkane, use the suffix -ane. Use -ene if the hydrocarbon is an alkene. Use -yne if the hydrocarbon is an alkyne. If more than one double or triple bond is present, use the prefix di- (2) or tri- (3) before the suffix to indicate the number of multiple bonds. |
| Step_3 | Give a position number to every carbon atom in the main chain. Start from the end that gives you the lowest possible position number for the double or triple bond, if there is one. If there is no double or triple bond, number the compound so that the branches have the lowest possible position numbers. |
Step_4 | Find the prefix: Name each branch as an alkyl group, and give it a position number. If more than one branch is present, write the names of the branches in alphabetical order. Put the position number of any double or triple bonds after the position numbers and names of the branches, just before the root. This is the prefix. Note: Use the carbon atom with the lowest position number to give the location of a double or triple bond. |
| Step 5 | Put the name together: prefix + root + suffix. |
Aromatic Compounds
If you completed the Concept Check activity on page 12, you drew a possible structure for benzene. For many years, scientists could not
determine the structure of benzene. From its molecular formula, C6H6,
scientists reasoned that it should contain two double bonds and one triple
bond, or even two triple bonds. Benzene, however, does not undergo the
same reactions as other compounds with double or triple bonds.
We know today that benzene is a cyclic compound with the equivalent
of three double bonds and three single bonds, as shown in Figure 1.9(A).
However, the electrons that form the double bonds in benzene are spread
out and shared over the whole molecule. Thus, benzene actually has six
identical bonds, each one half-way between a single and a double bond.
These bonds are much more stable than ordinary double bonds and do
not react in the same way. Figure 1.9(B) shows a more accurate way to
represent the bonding in benzene. Molecules with this type of special
electron sharing are called aromatic compounds. As mentioned earlier,
benzene is the simplest aromatic compound.
Figure 1.10 illustrates some common aromatic compounds. To name
an aromatic compound, follow the steps below. Figure 1.11 gives an
Naming an Aromatic Hydrocarbon
Step 1 Number the carbons in the benzene ring. If more than one type of branch is attached to the ring, start numbering at the carbon with the highest priority (or most complex) group. (See the Problem Tip.)
Step 2 Name any branches that are attached to the benzene ring. Give these branches position numbers. If only one branch is attached to a benzene ring, you do not need to include a position number.
Step 3 Place the branch numbers and names as a prefix before the root, benzene.
Chemists do not always use position numbers to describe the branches CHEM that are attached to a benzene ring. When a benzene ring has only two branches, the prefixes ortho-, meta-, and para- are sometimes used instead
of numbers.
Comentarios recientes