必修2-专题1-共价键教案

第一篇：必修2-专题1-共价键教案

苏教版 高一化学-课标 共价键教案9JT 教学目标： 知识目标：

1．使学生理解共价键的概念，初步掌握共价键的形成，加深对电子配对法的理解。2．能较为熟练地用电子式表示共价分子的形成过程和分子结构。3．使学生了解化学键的概念和化学反应的本质。能力目标：

1．通过对共价键形成过程的教学，培养学生抽象思维和综合概括能力； 2．通过离子键和共价键的教学，培养学生对微观粒子运动的想象力。情感目标：

1．培养学生用对立统一规律认识问题。

2．通过对共价键形成过程的分析，培养学生怀疑、求实、创新的精神。

3．培养学生由个别到一般的研究问题的方法。从宏观到微观，从现象到本质的认识事物的科学方法。教学重点：共价键

难点：化学键概念，化学反应的本质。教学过程：

引入：回顾氯化钠的形成，离子键的概念。提出氯化氢是如何形成的呢？ 播放动画：共价键，引出共价键的概念 板书：

二、共价键

1．概念：原子之间通过共用电子对所形成的相互作用，叫做共价键。

2．成键微粒：一般为非金属原子。

形成条件：非金属元素的原子之间或非金属元素的原子与不活泼的某些金属元素原子之间形成共价键。分析：成键原因：当成键的原子结合成分子时，成键原子双方相互吸引对方的原子，使自己成为相对稳定结构，结构组成了共用电子对，成键原子的原子核共同吸引共用电子对，而使成键原子之间出现强烈的相互作用，各原子也达到了稳定结构。板书：3．用电子式表示练习： 的形成过程。

讲解：从离子键和共价键的讨论和学习中，看到原子结合成分子时原子之间存在着相互作用。这种作用不仅存在于直接相邻的原子之间，也存在于分子内非直接相邻的原子之间。而前一种相互作用比较强烈，破坏它要消耗比较大的能量，是使原子互相联结形成分子的主要因素。这种相邻的原子直接强烈的相互作用叫做化学键。板书：

三、化学键

相邻原子之间的强烈的相互作用，叫做化学键。讨论：用化学键的观点来分析化学反应的本质是什么？

教师小结：一个化学反应的的过程，本质上就是旧化学键断裂和新化学键形成的过程。列表对比离子键和共价键

作业： 板书设计：

二、共价键

三、化学键

相邻原子之间的强烈的相互作用，叫做化学键。

列表对比离子键和共价键

第二篇：共价键我的教案

[复习]

1、必修中学过共价键概念。共价键：原子间通过共用电子对形成的化学键。

2、原子轨道、电子云概念。

[过渡]通过已学过的知识，我们知道电子是在核外一定空间运动的，元素原子形成共价键—————共用电子对时，电子云要发生重叠，它们又是通过怎样的方式重叠，形成共价键的呢？要想弄清楚这个问题，让我们共同学习今天的内容。

[板书]

第二章 分子结构与性质

第一节

共价键

[随堂练习]共价键是常见化学键之一，它的本质是在原子之间形成共用电子对，你能用电子式表示H2、HCl、C12分子的形成过程吗？

［投影］HCl的形成过程：

［讲］按共价键的共用电子对理论，不可能有H3。、H2Cl和Cl3分子，这表明共价键具有饱和性。我们学过电子云和原子轨道。两个成键原子为什么能通过共用电子对相结合呢？如何用电子云和原子轨道的概念来进一步理解共价键呢？

［探究］用电子云描述氢原子形成氢分子的过程如图2—l所示

一、共价键

[讲述]两个1s1电子 相互靠拢→电子云相互重叠→形成H2分子的共价键H-H。电子云在两个原子核间重叠，意味着电子出现在核间的概率增大，电子带负电，因而可以形象地说，核间电子好比在核间架起一座带负电的桥梁，把带正电的两个原子核“黏结”在一起了 ［板书］

2、共价键的形成条件：

(1)两原子电负性相同或相近

(2)一般成键原子有未成对电子

(3)成键原子的原子轨道在空间上发生重叠

3.共价键的本质：成键原子相互接近时，原子轨道发生重叠自旋方向相反的未成对电子形成共用电子对，两原子核间的电子云密度增加，体系能量降低 ［板书]

4、共价键的类型

（1）σ键：以形成化学键的两原子核的连线为轴作旋转操作，共价键电子云的图形不变，这种特征称为轴对称。如H-H键。

[设问]H2分子里的σ键是由两个s电子重叠形成的，可称为“s—sσ键”。s电子和p电子，p电子和p电子重叠是否也能形成σ键呢?

[讲]我们看一看HCl和C12中的共价键，HCl分子中的共价键是由氢原子提供的未成对电子ls的原子轨道和氯原子提供的未成对电子3p的原子轨道重叠形成的，而C12分子中的共价键是由2个氯原子各提供一个未成对电子3p的原子轨道重叠形成的。

[讲]未成对电子的电子云相互靠拢→电子云相互重叠→形成共价键单键的电子云图象。[板书] 特点：头碰头，轴对称，重叠程度大，稳定不易断裂

[板书]类型：s—sσ、s—pσ、p—pσ等。

［讲］形成σ键的原子轨道重叠程序较大，故σ键有较强的稳定性。共价单键为σ键，共价双键和叁键中存在σ键(通常含一个σ键)［过渡］p能级有三个呈哑铃形原子轨道，且相互垂直。有一个原子轨道头碰头形成σ键，另外两个原子轨道如何呢？给出自制模型让学生思考。

[板书]（2）π键：由两个原子的p电子“肩并肩”重叠形成

[讲述]π键的电子云形状与σ键的电子云形状有明显差别：每个π键的电子云由两块组成，分别位于由两原子核构成平面的两侧，如果以它们之间包含原子核的平面为镜面，它们互为镜像，这种特征称为镜像对称。π键与σ键不同，σ键的强度较大，π键不如σ键牢固，比较容易断裂。因而含有π键的化合物与只有σ键的化合物的化学性质不同，如我们熟悉的乙烷和乙烯的性质不同。

[板书] 特点：肩并肩、两块组成、镜像对称、重叠程度小，容易断裂。

小项目结σ键键型沿轴方向“头碰头”平行方向“肩并肩”轴对称镜像对称π键成键方向电子云形状牢固程度成键判断规律强度大，不易断裂强度较小，易断裂共价单键是σ键，共价双键中一个是σ键，另一个是π键，共价三键中一个是σ键，另两个为π键。［板书]

1、共价键的特性

（1）饱和性、决定分子的组成即原子结合成分子时的数量关系（2）方向性、依据最大重叠原理。决定了分子的立体构型 总结：共价键的分类：按电子云的重叠方式分：σ键和π键

按共用电子对数分为：单键、双键和三键

按共用电子对数是否偏移分为：极性共价键和非极性共价键

[过渡]方向性决定；了分子的空间构型，我们通过下面知识的学习，更好的理解共价键的方向性。这就是键参数。指导阅读P30表2-

1、表2-2了解一些共价键的键能、键长并思考问题

[板书]

二、键参数——键能、键长和键角

思考：键能与共价键的强度有什么关系？键能与化学反应能量变化有什么关系？怎样利用键能数据计算反应的热效应？

【板书】1.键能

气态基态原子形成1mol共价键释放的最低能量(或拆开1mol共价键所吸收的能量)，例如H-H键的键能为436.0kJ.mol-1 [说明] ①键能的单位是kJ·mol-1

②形成化学键通常放出热量所以键能通常取正值 ③键能越大，化学键越稳定

2.键长

形成共价键的两个原子之间的核间的平衡距离。共价半径与范式半径（资料卡片P32）

[说明] ①键长的单位都是pm=10-12m(P31注释)②键长越短往往键能就越大，共价键越稳定

3.键角

分子中两个相邻共价键之间的夹角称键角。

CO2 1800 H2O

104.50

NH3

107.50

CH4

109028’ 小结：键能/键长决定共价键的稳定性;键角决定了分子的空间构型。[过渡]观察P32表2-3列出了CO和N2的某些性质 [板书]

三、等电子原理 等电子体： 等电子原理：

2e-10e-

18e-微粒的考察、随堂练习本节小结 布置作业：

第三篇：Unit 1《Friendship》教案21(人教版必修1)

新课标 高一必修1 英语教案

Unit 1 Friendship Part One: Teaching Design(第一部分：教学设计)

Period 1: A sample lesson plan for reading

(ANNE‟S BEST FRIEND)Aims

To talk about friendship To read about friendship

Procedures I.Warming up

1.Warming up by assessing

A lot of people have only few possibilities of getting feedback about their own personality.In this exercise you will have the opportunity to get some feedback and to discuss it with a partner.While comparing your mutual judgments, certain prejudices or misunderstandings may appear, as people often do not know each other thoroughly enough to judge others correctly.Try to be honest!Self assessment

Of the following characteristics choose 5 that are particularly applicable to you personally.sociable, honest, friendly, easygoing, nervous, open-minded, anxious, careful, talented, talkative, nosy, thoughtful, generous, carefree, pessimistic, peaceful, optimistic, interesting, reliable, helpful, active, careless, caring, exact, adventurous, imaginative, hot-blooded, well-organised, trustworthy, patient, responsible, outgoing, kind, brave, warm-hearted, selfless, tolerant Partner assessment

Now choose 5 characteristic features which you think are especially applicable to your partner.sociable, honest, friendly, easygoing, nervous, open-minded, anxious, careful, talented, talkative, nosy, thoughtful, generous, carefree, pessimistic, peaceful, optimistic, interesting, reliable, helpful, active, careless, caring, exact, adventurous, imaginative, hot-blooded, well-organised, trustworthy, patient, responsible, outgoing, kind, brave, warm-hearted, selfless, tolerant 2.Warming up by describing

Have the students get into groups of four to describe their own ideal friend.Individual students must decide on TOP 5 character adjectives that could be used to describe the ideal friend and insist they have good reasons for their choice.Then let the group leader give the class a description of their ideal friend.3.Further applying

You may also have the students do the survey in the textbook, following the steps below.1.Get the students to make a list of three qualities a good friend should have.2.Have the students get into groups of four to find out what each has listed.3.Have a member of each group report on what their lists have in common and list them on the board.4.Ask the class whether or not they agree with all the qualities listed.5.Then have the students do the survey in the textbook.6.Have the students score their survey according to the scoring sheet on page 8.7.The teacher ask some students how many points they got for the survey and assess their values of friendship:

★ 4~7 points: You are not a good friend.You either neglect your friend‟s needs or just do what he/she wants you to do.You should think more about what a good friend needs to do.★ 8~12 points: You are a good friend but you sometimes let your friendship become too important, or you fail to show enough concern for your friend‟s needs and feelings.Try to strike a balance between your friend‟s needs and your own responsibilities.★ 13+ points: You are an excellent friend who recognizes that to be a good friend you need balance your needs and your friend‟s.Well done.(You may also show your students the results above and let themselves self-reflect upon their own values of friendship)II.Pre-reading

To focus the Students‟ attention on the main topic of the reading passage.To activate their previous knowledge on the topic.III.Talking and sharing

Work in groups of four.Tell your group mates how you reflect on these questions.1.Why do you need friends? Make a list of reasons why friends are important to you.2.What do you think a good friend should be like? List what a good friend should do and share the list with your partners.3.Does a friend always have to be a person? What else can be a friend? 4.Do you think a diary can become your friend? Why or why not?

Instructions: The teacher can give each group one of these questions above to talk about.Then let the class share their ideas.It‟s better to stimulate the students to challenge their classmates‟ opinions about these questions.Possible answers

Q1: Reasons I need friends:

※ to cope with stressful situations in life

※ to share my worries and secrets in my inner world ※ to show my concern for other people ※ to let other people share my happiness

※ to unfold to other people the secrets in my heart(to name but few.)Q2: A good friend should: ※ tell me the truth(honest)※ be good to me(friendly)

※ be willing to consider or accept others’ ideas or opinions(open-minded)※ be willing to help others(generous or helpful)※ be good-tempered

※ think about what others need and try to help them(caring)※ be loyal to their responsibility(responsible)※ not easily upset(easy-going)

※ be out-going(like to meet and talk to new people)

※ be tolerant(allow other people to have different opinions or do something in a different way)

※ be selfless(to name but few)

Q3: What else can be a friend? Answers can be various.(omitted)

Q4: Students‟ answers may vary but must include a reason.Yes.I think it can be, because I can set down how I feel every day in my diary, and let other people read it to share my feelings some time later.Above all, it feels good to write down my thoughts and feeling on paper when I am sad or lonely.IV.Reading

1.Looking and guessing

Work in pairs.Look at the pictures and the heading and guess what the text might be about.1).Imagine what it might be like if you had to stay in your bedroom for a whole year.You could not leave it even to go to the WC or to get a cup of tea.How would you feel?

2).What would you choose if you are only allowed to have five things with you in the hiding place because there is very little room?

2.Reading to summarise the main idea of each paragraph.Skim the text and summarise the main idea of each paragraph in one sentence.Para.One: Anne made her diary her best friend whom she could tell everything.[来源:Zxxk.Com] Para.Two: Anne‟s diary acted as her true friend during the time she and her family had to hide away for a long time.Para.Three: Having been kept indoors for so long, Anne grew so crazy about everything to do with nature.3.Language focus

Next you are to read and underline all the useful expressions or collocations in the passage.Copy them to your notebook after class as homework.laugh at, go through, make/call + O +Noun(as O.C.), hide away, set down，grow crazy about, do with…, there was a time when…, keep sb.spellbound, on purpose, in order to do sth., far too +adj./adv, happen to do sth., it was the first/second time that …, face to face V.Closing down

Closing down by doing exercises

To end the lesson you are to do the comprehending Exercises 1 and 2.Closing down by discussion of ideas

Work in groups of four.Discuss the ideas put forward in the reading passage.It does not matter whether you agree or disagree.What is important is that you should have a reason for what you say.Also you can put forward your own ideas, either criticising the text or using it as a support:

★ What would you do if your family were going to be killed just because they did something the Emperor did not like? ★ Where would you plan to hide?

★ How would you arrange to get food given to you every day?

What would you do to pass the time? Language chunks from Unit 1 Friendship

add up, get sth.done, calm sb.done, have got to, go on holiday, talk care of, walk the dog, get loose, pay for sth, cheat in the exam, should have done, someone else‟s, laugh at, go through, hide away, set down, a series of, a hiding place, I wonder if…, grow/be/become crazy about, could have done, keep sb.spellbound, keep doing, stay awake, on purpose, in order to, by oneself, far too much, it was(is)the first time that…, face to face, feel lonely/sit alone, save one‟s life, be concerned about, with so many clothes on, have trouble with sb, at the moment, get along(well)with sb./ sth, enjoy doing, be/become/make friends with, be/fall in love(with), try sth.out on sb.ask for advice, give sb.some advice on…, make an effort to do sth., join in sth., show one‟s interest in, far and wide, pay attention to, look to one‟s own concern, share one‟s thoughts and feelings with sb, come to a conclusion, be prepared to do sth., a heart-to-heart talk, hurt one‟s feelings, change one‟s mind, live in peace, go on a picnic, get away with, feel at home, in need[来源:学科网ZXXK] Period 2: A sample lesson plan for Learning about Language

(Direct & Indirect Speech(Ⅰ)statements & questions)Aims

To discover useful words and expressions To discover useful structures [来源:学&科&网] Procedures I.Warming up

Warming up by discovering useful words and expressions

Turn to page 4 and do Exercises 1, 2, 3 and 4 first.Then check your answers with your class partner.II.Learning about grammar: Direct and Indirect Speech

1.Direct Speech

In direct speech, the original speaker's exact words are given and are indicated by quotation marks.★ “I don’t know what to do,” said Dean.In some grammar books, „said Dean‟ is referred to as a reporting clause.“I don't know what to do,” is referred to as the reported clause.2.Indirect Speech

In indirect speech, the exact meaning of the speaker‟s words is given, but the exact words are not directly quoted.★ Dean said that he didn‟t know what to do.To convert direct speech into indirect speech:

If the main verb is past tense, present tense verbs in „that clause‟ must also be changed to past tense.Dean said that he didn‟t know what to do.First and second person pronouns must be changed to third person pronouns.Dean said that he didn‟t know what to do.(The word „that‟ can often be left out: Dean said he didn‟t know what to do.)3.Indirect Questions

Direct question: “Did Marama‟s horse win a prize?” Owen asked.Indirect questions: Owen asked whether(or if)Marama‟s horse had won a prize.The same rules apply to indirect questions as to indirect statements.The difference is that a wh-clause is used instead of a that clause.Direct question: “Why won‟t you marry me?” asked Donald.Indirect question: Donald asked her why she wouldn‟t marry him.In telling a story or recounting events, a speaker using direct speech has all the resources of intonation to produce a lively account.Because indirect speech is always speech reported by someone else, the account is more reserved and restrained.“What shall we do?” asked Bev.“Don‟t worry, Bev,” said Duncan, “I‟ve got a plan.”

Bev asked Duncan what they should do.He told her not to worry and that he had got a plan.The ability to change direct speech into indirect speech is a useful skill for those engaged in taking the minutes of a meeting or reporting on events.Direct speech: “First of all, I would like to thank everybody who helped with the fair.The results were very good, and we will now be able to buy two more computers.”

Indirect speech: The principal said that he would like to thank everybody who had helped with the fair.He announced that the results were very good and that the school would now be able to buy two more computers.III.Discovering words and expressions

Do exercises 1, 2, 3 and 4 on page 4 and 5.Check your work with your partner‟s.IV.Discovering structures

Do exercise 1 and 2.Check your work with your partner‟s.Period 3: A sample lesson plan for Using Language

(A letter from a student to the editor of The 21st Century)Aims

To listen to a letter about friendship

To speak about a questionnaire about friendship To write advice about friendship

To write a few lines describing a friend Procedures I.Warming up

1.Read the letter to Miss Wang and find out what was upsetting Lisa.2.Listen to what Miss Wang says, and then answer the questions in Exercise 2.3.Listen to the tape again and try to spell out the missing words in Ex 3.II.Talking about designing a questionnaire

Work in groups of four.Design a questionnaire to find out what kind of friends your classmates are.Ask the Students to use the quiz in the Warming Up as an example.Note: The students should be talking while they are doing the task.This provides the students with the opportunity to practise expressing thought and concern in matters of immediate concern and interest.Tell the students to follow these steps:

Step1: In your group, come up with four situations among friends.Design four questions accordingly with three possible answers.Step2: Put the four questions together and form a questionnaire.Step3: Check the questionnaire through and try it out on your own group.Step4: Share your questionnaire with another group and try each other‟s questionnaires.Sample questionnaire:

This questionnaire has four questions, and each question is followed by a set of possible answers.Please read the questions, and then consider which response fits you best.1.Why am I close friends with this person now?

A.Because being friends with him/her helps me feel important.B.Because my friend would be upset if I ended the relationship.C.Because he/she is someone I really enjoy sharing emotions and special events with.2.Why do I spend time with my friend?

A.Because my friend would get mad at me if I didn‟t.B.Because it is fun spending time with him/her.C.Because I think it is what friends are supposed to do.3.Why do I listen to my friend‟s problems, or to what my friend has to say?

A.Because my friend praises me and makes me feel good when I do.B.Because it‟s interesting and satisfying to be able to share like that.C.Because I really value getting to know my friend better.4.Why do I keep promises to my friend?

A.Because I believe it is an important personal quality to live up to my promises to a friend.B.Because it would threaten our friendship if I were not trustworthy.C.Because I would feel bad about myself if I didn‟t.Scoring Sheet:

Q1 A 1point Q2 A 1point Q3 A1 point Q4 A3 points

B 2points B 2points B2 points B2 points C 3points C 3points C3 points C1 point

☆ 4~6 points: You are not a good friend.You either neglect your friend’s needs or just do what he/she wants you to do.You should think more about what a good friend needs to do.☆ 7~9 points: You are a good friend but you sometimes let your friendship become too important, or you fail to show enough concern for your friend‟s needs and feelings.Try to strike a balance between your friend‟s needs and your own responsibilities.☆ 10+ points: You are an excellent friend who recognizes that to be a good friend you need balance your needs and your friend‟s.Well done.Students work in groups and try their own questionnaires in the school to collect more information about students‟ reflection of the values of friendship.III.Guided writing

1.Read the letter to the editor from Xiaodong and make sure you know what problem Xiaodong has.2.Discuss in groups of four.Think what advice you can give Xiaodong.3.Write your advice to Xiaodong as an editor individually.Sample writing: Dear Xiaodong，Some people like talking with others, but some people are shy.If you fall into the second group, it can be hard to make friends.But you can change the situation.What are you interested in? If you like basketball, for example, you could talk with some of your classmates who like basketball.The easiest way to start talking to people is to find something you have in common.If you are standing beside a group of your classmates, join in their discussion if you know something about the subject they are discussing.But if you don‟t, you shouldn‟t feel afraid to say, for example, “That sounds interesting, what is it about?” Once you start talking to one person, it will get easier to talk to others.Find one person you have something in common with, and once you become friends with him, his friends will start talking to you too.Good luck!Editor

IV.Writing assessment

1.Can you give Xiaodong some good advice? 2.I s your letter well developed?

3.Are your ideas well organized to the point?

4.Do you have a good choice of words and idioms in your writing? 5.Do you get a good mastery of complex structures of language?

6.What kind of mistakes have you made in your writing? What can you do to avoid such mistakes? V.Further Applying

Here are some proverbs about friends and friendship.Read them carefully and pay attention to the sentence stress and intonation.Then write a passage.Choose some you agree and explain why.Then choose some you disagree and explain why.■You may also have the students complete the task as homework after class.Part Two: Teaching Resources(第二部分：教学资源)

Section 1: Background reading on friendship Friendship Quotes

I.Questions about friendship

1.What is the main problem in friendship?(leaving someone out)

2.How do you keep a friend?(treat someone like you want to be treated)3.What is a good friend?(somebody whom you can depend on)

4.What if your friend said they wouldn‟t be your friend if you were another person‟s friend?(That “friend” would not mind if she were really your friend.)★ “True friendship is like sound health;the value of it is seldom known until it be lost.”---Charles Caleb Colton

★ “A friend is one who walks in when others walk out”---Walter Winchell ★ “A friend is one who believes in you when you have ceased to believe in yourself.”---Lysha

★ “The better part of one's life consists of his friendships.”---Abraham Lincoln ★ “Advice is like snow;the softer it falls, the longer it dwells upon, and the deeper it sinks into the mind.”---Samuel Taylor Coleridge

★ “Friendship is the golden ribbon that ties the world together.”---Kristina Kentigian

★ “Friends are the sunshine of life.”---John Hay ★ A friend in need is a friend indeed.II.Tips on being a good friend

※ Treat your friends the way you want to be treated.※ Keep secrets that are told to you.※ Pay attention when your friend is talking.※ Keep your promises.※ Share things with your friend.※ Tell your friend the truth.※ Stick up for your friend.III.What kind of friend are you?

1.If your friend tells you a secret that isn‟t bad but you promised not to tell anyone, you will________.A.tell everyone B.keep the promise

2.If you know your friend is planning to cheat on a test, you will________.A.tell your teacher B.let your friend cheat

C.help your friend study for the test so she won't feel she needs to cheat 3.If your friend tells you a secret and it may cause his or her death, you will________.A.tell a trusted adult B.keep it a secret C.tell your friends

You may print this sheet and answer the questions.Then discuss the answers with your friends.A true friendship should:

☉encourage you to live your dream.☉support you toward your goals.☉sympathize for your losses and help you find a silver lining.☉build your self-esteem.If happiness and life-satisfaction are your goals, your friends should be chosen on the basis of how well they can accomplish those four goals.Happiness is a personal choice that comes from within.But, as the friendship poem says, it surely doesn‟t hurt to have supportive friendships that help us achieve our goals.IV.Self-reflection upon friendship

Read the following statements and then tick Yes(√)or No(×)to show your opinions upon friendship.1.Friendship is very important to me.2.I have a lot of friends.3.There can be true friendship between a schoolboy and a schoolgirl.4.I am very kind to my friends.5.I think everyone should have friends.6.Friends must have the same character.7.I keep a diary and think it is my close friend.8.When my friend is in trouble, I am always ready to help.9.I don‟t like to talk to others very much.I like to be alone.10.I keep a pet animal and treat it like a friend.A friendship poem

Choose friends wisely, the portrait they paint

Is who you are and who you ain‟t.Friendship is life‟s great support When friends are of the right sort.For all your dreams do they make room, Or bring you down with doom and gloom? You will know a friendship is true.When it brings out the best in you.It‟s true.You can tell a person by the company she keeps.Our friendships not only tell a lot about who we are---they make us who we are.The friendship poem above says it all.You will know a friendship is true when it brings out the best in you.Take a look at your friends.Do they bring out the best in you? That might seem like a silly question.We all tend to think, “Of course they bring out the best in me.I wouldn‟t be friends with them otherwise.” Section 2: Vocabulary teaching strategy I.The role of vocabulary teaching

In the context of learning English as a foreign language, a learner is forced to be autonomous and independent and make conscious effort to learn vocabulary outside the classroom simply because the exposure to the target language is limited in class.So teachers cannot rely on their students „picking up‟ lexical items.This makes explicit vocabulary teaching necessary.However, vocabulary is notoriously difficult if not impossible to teach because of the complexity of its linguistic, semantic and psycho-cognitive aspects II.Best approach

There are no universally useful strategies and they contribute to vocabulary learning in different ways.Students use a number of strategies, often simultaneously.The efficiency of vocabulary learning depends on how students combine individual strategies.If students combine and employ individual strategies from different groups they will be more successful in developing the target language lexicon.Thus, the ideal combination would be that of strategies from all four groups.The teacher should create activities and tasks(to be done both in and outside class)to help students to build their vocabulary and develop strategies to learn the vocabulary on their own.Students experiment and evaluate and then decide which to adopt or reject since strategies are not intended to be prescriptive.III.Practical activities

Here is a selection of practical activities that direct learners towards using strategies of vocabulary learning.1.The useful alphabet(self-initiated independent learning)

Each student gets a letter and has to find 5, 10 or 15 words he or she thinks would be useful for him or her.He or she then report to the class, perhaps as a mingle activity, using word cards(on one side they write the letter, on the other the information on the word-spelling, pronunciation, definition).2.Word bag(formal practice)

This is to get your students to write down new words they hear in class.At the beginning of the term/course, divide students into groups of about 5 and give each group a number(e.g.1-6).At the beginning of each class, give each group about 10 cards on which they write the number of their group and the new words they hear in class.At the end of each class, they put their cards into the “word bag” and every 2 weeks you check whether they still know those words and which group has the most cards.In the end there are two winners: the group that has the most cards, and the one that knows more words.3.Especially for you(Functional practice)

The teacher prepares a list of words.Each student gets one word, which is prepared especially for him or her.The trick is that each student gets a word whose initial letter is the same as the initial of the student‟s first name, e.g.Linda gets listless.Each student must look it up in the dictionary during the class and after a few minutes report to the class.E.g.“My name is Linda and I‟m listless.That means that I am...(definition)...”.For homework students can do the same using their surname.4.Word tour(memorizing)

Instructions for your students: Think of a town or city you know well.Imagine that you are organizing a sightseeing tour.Think of 5 places you would include on your tour and write down the order in which the tourists would visit them.Learn your tour off by heart so that you can picture it in your mind.Whenever you have 5 new English words to learn, imagine these words are the tourists on your tour and picture the words in the places on your tour like this.Tour: Trafalgar Square;Buckingham Palace;Houses of Parliament;Westminster Abbey;Downing Street.Words to learn: apron, dustpan, vacuum cleaner, feather duster, broom.Imagine Nelson on his column in Trafalgar Square wearing an apron, the queen brushing the floor in Buckingham Palace and using a dustpan...Section 3: Words and expressions from Unit 1 Friendship

add v.1.put something with something else or with a group of other things: Do you want to add your name to the list? 2.to put two or more numbers together in order to calculate the total: Add 6 and 6 to make 12.3.to increase the number: The sales tax adds 15% to the price of clothes.4.to say some more that is related to what has already been said: That‟s all I want to say.Is there anything you‟d like to add.Other verbal phrases of “add”

add to: to make something larger and more noticeable: Our explanation seemed only to add to his bewilderment.add up: to calculate the total of several numbers: Add your scores up and we‟ll see who won.add up to: to have a particular result: His schooling added up to no more than one year.point: n.1.small spot: The stars shone like tiny points of light in the sky.2.sharp end: a knife with a very sharp point.3.a unit used to show the score in a game or sport: She lost three points for that fall.(in a skating match)

upset: 1.vt.& vi.to make someone feel unhappy or worried: I‟m sorry, I didn‟t mean to upset you.2.adj.(not before noun)unhappy and worried: She was still upset about the argument that she had had with Harry.ignore: vt.1.to behave as if you had not seen or heard someone or something(不理睬): Either she didn’t see me wave or she deliberately ignored me.2.to pay no attention to something that you have been told or that you know about(忽视): Some drivers simply ignore speed limits.calm: 1.adj.quiet and without excitement, nervous activity or strong feelings: Keep calm, and try not to panic.2.vt.& vi.to make someone or something quiet after strong emotion or nervous activity: Charlie tried to calm the frightened children.3.calm down: vt &vi.to become quiet or make someone quiet after strong emotion or nervous activity: Calm down and tell me what happened.concern: 1.n.worry: something that worries you or a feeling of worry: There is growing concern about/over the effects of pollution on health.The rise in unemployment is of great concern to the government.2.vt.to make someone feel worried or upset: The fact that she spends so much money on her own really concerns me.More and more people are concerning themselves with/about environmental problems.3.be concerned about/for/with: Ross has never been concerned about what other people think of him.Rescuers are concerned for the safety of those trapped in the mine.This story is concerned with a Russian family in the 19th century.cheat: 1.vi.to behave in a dishonest way in order to win or to get a advantage in a competition, game or examination: Jack always cheats at cards.2.vt.to trick someone who trusts you.share: vi & vt.1.use equally: The last bus had gone, so the three of us shared a taxi.I shared a room with him at college.2.to have the same opinion, experience, feeling etc as someone else: I share your concern about this problem.3.to tell other people about an idea, secret, problem: It‟s always better to share your worries.4.n.part of sth.: I do my share of the housework.Don‟t worry---you‟ll get your fair share.set down: to write down something so that you have a record of it: I want to set down

my feelings on paper.Other verbal phrases of “set”

set apart: to make someone or somebody different from other people or things.set aside: to keep some money or time for a special purpose set off: to start to go somewhere/ to cause a explosion

set out: to start a journey/ to talk about something in an organized way set up: to start an organization/ to build something

crazy adj.1.impractical;foolish: That‟s the craziest idea I‟ve ever heard.2.mad;ill in the mind: Turn that music down---it‟s driving me crazy.3.be crazy about=to like sb.very much, or be very interested in something: The boy is

crazy about football.4.like crazy=very hard: We have to work like crazy to get this finished on time.purpose: 1.n.an intention or plan;the feeling of having an aim in life: The discussion serves a twin purpose---instruction and feedback.Tom went for a walk, with no definite purpose in mind.2.on purpose=deliberately trust: 1.n.a strong belief in the honesty, goodness etc.of someone or something e.g.You shouldn‟t put your trust in a man like that.2.vt.to believe that someone is honest and will not harm you or cheat you: I trusted Max, so I lent him the money.Can he be trusted to look after your pet dog?

suffer: vt.& vi.1.to experience physical or mental pain: At least he died suddenly and didn‟t suffer a lot.2.to be in a very bad situation that makes things very difficult for you: If you break the law, you must be prepared to suffer the punishment.She was very generous to him but she suffered for it when he ran away with all her money.3.to experience something unpleasant: The car suffered severe damage in the accident.get along(with): 1.to have a friendly relationship: If you two are going to share a room, you‟d better learn how to get along.I‟ve always found him a bit difficult to get along with.2.to progress you are doing: How are you getting along with your English studies?

Other verbal phrases of “get”:

get about/around:(news)get widespread get away: to succeed in leaving a place

get back: to return to a place;to have sth.returned to you get down: to make sb.feel unhappy;

get down to sth./doing sth.: to start doing something that needs a lot of time or energy.get over: get well after an illness;to do and finish sth.difficult get through: to pass a test or exam

communicate: vi.to express your thoughts and feelings: Parents sometimes find it difficult to communicate with teenage child.

第四篇：邳州市第二中学高中化学选修三21共价键教案（写写帮推荐）

过程和方法目标：

1、通过对共价键形成过程的学习，感悟微观粒子形成方式的多样性。

2、通过对共价键形成过程的教学，培养学生抽象思维和综合概括能力；

3、通过离子键和共价键的教学，培养学生对微观粒子运动的想象力。情感态度与价值观目标：

1、培养学生用对立统一规律认识问题。

2、通过对共价键形成过程的分析，培养学生怀疑、求实、创新的精神。

3、培养学生由个别到一般的研究问题的方法。从宏观到微观，从现象到本质的 认识事物的科学方法。

二、教学分析

1、学情分析：作为区级重点中学的学生，其理解和感悟能力相对较强，应而适当提高教学的密度和容量，以提高教学效率。

2、重点、难点： 共价键 共价键的形成和本质。

3、教学策略和方法：引导学生探究共价键形成的奥秘。从设疑、探究到释疑，从宏观到微观，从现象到本质，通过演绎推理揭示事物的本质。

三、教学过程： 引言：

同学们，在前面我们已经提到了化学反应的实质就是旧的分子被破坏变成原子，原子重新组合构成新的分子。那么，原子是通过什么作用构成分子的呢？那就是前一节课我们学到的化学键。（设问）那么，什么是化学键呢？（学生回答）上一节课我们已经体会了其中的一类化学键，既为离子键。现在，我们一起来回顾一下离子键的形成过程。

NaCl形成过程（PPT）电子式表示形成过程：

设问：那么形成离子键的条件是什么呢？（学生回答）

那么非金属原子之间又是怎样产生作用的呢？这就是今天我们要学习的内容。

板书：

§3.3共价键

一、共价键的形成点燃

H2+Cl2 →2HCl PPT演示HCl共价键的形成过程

电子式表示形成过程：

1．定义：原子通过共同电子对而形成的化学键叫共价键

全部由共价键构成的化合物叫共价化合物 2．形成条件：非金属元素原子间形成

设问：氯化氢的分子式是 HCl，而水、氨气、甲烷的分子式是 H2O、NH3、CH4，为什么共价化合物原子间按一定的数目互相结合呢？

（学生看书P71下面两自然段，并回答）

3．共价键的饱和性：原子成键时需达到饱和电子层结构的趋势决定共用 电子对的数目，从而决定了成键原子的数目

4．共价键的分类

极性共价键：HCl、H2O、NH3 等 共价键

非极性共价键： H2、O2等

5．电子式表示以及结构式

例1：用电子式表示H2O、N2、MgCl2物质的形成过程

练习：用电子式表示HF、NH3、CaCl2物质的形成过程（学生板书）

结构式：用短线代替共用电子对而表示的式子。（一根短线表示一对共用电子对）

二、共价分子和分子式

（阅读P72教材）

设问：为什么离子化合物的化学式不能看作分子式？而共价分子的化学式就是分子式？举例说明

1、共价分子：

2、分子式和化学式： 作业：同步课课练 小结：离子键和共价键的比较。P65--66

第五篇：《共价键》说课稿

共价键说课稿

高一化学组

李媛媛

《共价键》说课稿

《化学键》是高中化学必修2第一章物质结构 元素周期律中第三节的内容。共包括离子键、共价键、分子间作用力和氢键几部分内容，本节课我要说课的内容是共价键，下面我将从以下几个方面进行说课：

一、说教材：

1、教材的地位和作用

“共价键”是《化学（必修）2》中第一章第三节内容，继初中的物质变化、化学反应之后，通过对化学键概念的建立，帮助学生从微观角度认识物质的构成和化学反应的本质；同时以“化学键”为桥梁，引导学生从物质变化和能量变化两个角度认识化学反应，为后面研究化学反应的利用奠定基础。

2、教学目标：

确立依据：化学键存在于微观结构中，我们无法进行观察，只能通过CAI演示，使学生去了解形成过程。这部分内容属于化学基本概念，这在高考试题中也属于重点，所以很有必要去突破这部分内容。知识与技能：

（1）使学生理解共价键的概念，初步掌握共价键的形成，加深对电

子配对法的理解。

（2）能较为熟练地用电子式结构式表示共价分子的形成过程和分子

结构。

（3）理解极性键、非极性键的概念。

兴趣，调动学生内在的学习动力。

2、小组讨论

采用讨论法让学生畅所欲言、各抒己见，通过小组讨论，学会思考、分析和总结。

3、多媒体教学

本节教材概念多，内容比较抽象，理论性强，可充分利用直观教学手段，使抽象概念形象化。

三、说学法

本节课我通过启发学生发现问题，自然而然提出问题，通过观看动画、问题讨论，并让学生用自己的语言进行归纳，从而解决问题，使学生在整个课堂教学中感受成功的乐趣，同时又学会如何去发现问题。

四、说教学过程

本节先复习离子键，使学生明确我们学习的离子键与初中学习的各种微粒构成物质的关系，引出本节课要解决的问题：分子如何构成微粒？原子能否直接构成物质？这样设计，既是初中的内容和高中必修内容有一个很好的衔接，又能复习上一节课学习的离子键。在进行共价键形成的教学时，以氢分子、氯分子和氯化氢分子为例说明共用电子对如何使两个原子相互结合在一起，形成新的一种类型的化学键――共价键，指出形成共价键后可以使能量降低，达到稳定结构。然后再引导学生思考稳定结构的意义，并用电子式举出几个常见的共价分子形成过程中达到稳定结构时如何形成共作电子对的，让学生学会用电子式表示共价分子。由于用电子式表示共价分子相对繁

为例分析一下共价键的形成。[多媒体演示] 师：在HCl的形成过程中，氢分子被破坏成氢原子，氯气分子被破坏成氯原子，那么，当氢原子和氯原子相遇时，它们是通过什么作用结合成氯化氢分子的呢? 生：它们是通过共用电子对形成氯化氢分子的。

师：对。从氯原子和氢原子的结构来分析，由于氯和氢都是非金属元素，不仅氯原子易得一个电子形成最外层8个电子的稳定结构，而且氢原子也易获得一个电子，形成最外层两个电子的稳定结构。这两种元素的原子获得电子难易的程度相差不大，所以相遇时都未能把对方的电子夺取过来。这两种元素的原子相互作用的结果是双方各以最外层一个电子组成一个电子对，电子对为两个原子所共用，在两个原子核外的空间运动，从而使双方最外层都达到稳定结构。这种电子对，就是共用电子对。像氯化氢这样以共用电子对形成分子的化合物，叫共价化合物。而原子之间通过共用电子对所形成的相互作用，就叫做共价键。 [多媒体板书]

1、定义：原子之间通过共用电子对所形成的相互作用。

2、成键微粒： 原子

3、相互作用： 原子间通过共用电子对所产生的强烈的相互作用。

（即原子间的静电作用.）

4、成键条件： 一般由同种或不同种非金属与非金属元素原子形

3下列化合物分子中只有共价键的是：D A)BaCl2 B)NaOH C)(NH4)2SO4 D)H2SO4 [推进] 练习后进行离子化合物共价化合物比较，作为本节课重点，务必使学生分清离子键和共价键，离子化合物和共价化合物。【第二课时】 [复习] 练习离子化合物电子式的书写，引出共价化合物电子式的书写。并等直接讲解HCl、Cl2、NH3等电子式结构式的书写。[推进]讲解电子式表示共价化合物形成过程，并练习。

请同学们回忆用电子式表示离子化合物的形成过程，它与表示共价化合物形成过程的有哪些区别呢？

生1：没有小弧线表示电子的得失

生2：生成的HCl中Cl原子也没有用括号括起来

为什么用电子式表示离子化合物与表示共价化合物有如此区别呢？这是因为在氯化氢分子中，共用电子对仅发生偏移，没有发生电子得失，未形成阴、阳离子，因此，书写共价化合物的电子式不能标电荷。而氯化钠形成过程中钠原子完全失去电子给氯原子形成钠离子和氯离子。因此两者电子式的表示是不同的，同学们要注意这点区别。[多媒体展示] 练习：用电子式表示下列共价化合物的形成过程。

阴、阳离子间通过静电作用形成的化学键

阴、阳离子相 互作用

活泼金属和活泼非金属得失电子成键

离子化合物

共用电子活泼金属和对不发生活泼非金属偏移 得失电子成键

共用电子对偏向一方原子

相同非金属元 非金属单质、素原子的电子 某些化合物 配对成键

不同非金属元 共价化合物和 素原子的电子 某些离子化合 配对成键

物 [课堂小结]

本节课我们主要介绍了共价键。希望同学们要注意离子键与共价键的区别，注意极性键与非极性键的区别，注意用电子式表示离子化合物和共价化合物的区别。深入理解化学键的内涵。学会判断离子键、共价键。

[布置作业]