tài liệu tập huấn giáo viên chuyên ngành hóa bằng tiếng anh

TÀI LIỆU TẬP HUẤN GIẢNG VIÊN DẠY CHUYÊN NGÀNH BẰNG TIẾNG ANH KHOA: HÓA HỌC MỤC LỤC BÀI 1: KINH NGHIỆM XÂY DỰNG CHƯƠNG TRÌNH MƠN HĨA HỌC BẰNG TIẾNG ANH BÀI 2: MATTER AND CLASSIFICATION OF MATTER BÀI 3: ELEMENTS AND PERIODIC TABLE 12 BÀI 4: THE ALKALI METALS 23 BÀI 5: ANKANES 32 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh BÀI 1: KINH NGHIỆM XÂY DỰNG CHƯƠNG TRÌNH MƠN HĨA HỌC BẰNG TIẾNG ANH 1.1 Cơ sở lý thuyết Chương trình chi tiết giáo dục đại học ngành Sư phạm Hóa học dạy tiếng Anh xây dựng sở chương trình khung giáo dục đại học ngành Sư phạm Hóa học trình độ đại học, ban hành theo định số 2682/QĐ – ĐHSP HN, ngày 21 tháng năm 2009 Hiệu trưởng trường Đại học Sư phạm Hà Nội Chương trình chi tiết giáo dục đại học ngành Sư phạm Hóa học tiếng Anh xây dựng sở kế thừa bề dày truyền thống gần 64 năm đào tạo giáo viên khoa Hóa học, trường Đại học Sư phạm Hà Nội, kết hợp với nguyên tắc đảm bảo tính đại, tính hiệu quả, tính hệ thống tính phát triển, tính thực tiễn mềm dẻo Trên sở đó, chương trình phát triển phù hợp với yêu cầu đòi hỏi ngày cao đời sống xã hội, hòa nhập quốc tế khu vực, thực tốt nhiệm vụ đào tạo giáo viên giảng dạy Hóa học trường THPT Chương trình đào tạo nhằm đào tạo đội ngũ giáo viên có lực chun mơn, nghiệp vụ chất lượng cao, có khả giảng dạy Hóa học phố thơng tiếng Anh, thể đổi nội dung phương pháp đào tạo theo hướng cập nhật với quốc tế, đồng thời phù hợp với điều kiện Việt Nam Chương trình chi tiết giáo dục đại học ngành Sư phạm Hóa học dạy tiếng Anh xây dựng đáp ứng yêu cầu chuẩn đầu đào tạo cán có đủ lực làm giáo viên dạy học Hóa học cấp học trung học sở, trung học phổ thơng tiếng Anh Có ý chí vươn lên có đủ khả tiếp tục học tập để trở thành giáo viên trường trung học chuyên nghiệp, trường cao đẳng đại học; cán nghiên cứu trung tâm nghiên cứu khoa học, viện nghiên cứu, sở sản xuất thuộc ngành Hóa học, Mơi trường, sở sản xuất kinh doanh có liên quan đến lĩnh vực Hóa học Sinh viên tốt nghiệp ngành Sư phạm Hóa học có đủ khả tiếp tục học tập nghiên cứu chuyên môn trình độ thạc sỹ tiến sỹ hóa học, có đủ khả để xin học bổng nước Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh 1.2 Tiến trình xây dựng: - Xây dựng chương trình đào tạo cử nhân sư phạm Hóa dạy tiếng - Anh Xây dựng khung trương trình chi tiết - Xây dựng giảng tiếng Anh Tiến hành dạy mẫu, rút kinh nghiệm - Chỉnh sửa tài liệu - Nghiệm thu chương trình tài liệu giảng dạy Hóa học tiếng Anh Tiến hành dạy cho sinh viên khoa Hóa học Hàng năm có tổ chức rút kinh nghiệm, chỉnh sửa chương trình, đề cương chi tiết giảng cho hoàn thiện Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh BÀI 2: MATTER AND CLASSIFICATION OF MATTER Vocabulary Matter Component Pure substance Proportion Element Uniform Compound Atom Mixture Molecule Homogeneous Combination Heterogeneous Properties Composition Dictionary definitions of chemistry usually include the terms matter, composition, and properties, as in the statement that “chemistry is the science that deals with the composition and properties of various forms of matter” Matter is anything that occupies the space and displays a property known as mass Every human being is an object of matter We all occupy space, and we describe our mass though a related property, our weight All the objects that we see around us are objects of matter The gases of the atmosphere, even though they are invisible, are example of matter; they occupy space and possess mass Composition refers to the parts of components of a sample of matter and their relative proportions Ordinary water is comprised of two simpler substances – hydrogen and oxygen – present in certain fixed proportions Properties are those qualities or attributes that can be used to distinguish one sample of matter form others Matter is classified into two broad categories, namely, pure substances and mixtures A pure substance can be either an element or a compound The composition and properties of an element or compound are uniform Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh throughout a given sample and from one sample to another A chemical element is a substance comprised of a single type of atom The elements are the building blocks of our nature An element is either discovered in nature or synthesized in the laboratory in pure form that cannot be separated into simpler substances by chemical methods Currently, there are about 118 elements discovered; some are found to be unique; no two elements are alike Elements are made up of tiny particles called atoms Atoms are the smallest particles of an element that have the chemical properties of that element Each element contains only one type of atoms The atoms of one element are not the same as the atoms of another element Most of the elements exist as monoatomic forms, which means that the smallest individual complete parts of these samples of pure elements are single atoms Seven of the known elements are called diatomic elements, because they are found in nature in their elemental form as two-atom molecules The seven diatomic elements are chlorine (Cl2), fluorine (F2), bromine (Br2), iodine (I2), hydrogen (H2), oxygen (O2), and nitrogen (N2) A compound is the substance formed by the chemical union of two or more element The number of compounds now known is in the millions In some cases we can isolate a molecule of a compound A molecule is the smallest entity having the same proportions of the constituent atoms as does the compound as a whole A molecule of water consists of three atoms – two hydrogen atoms joined to a single oxygen atom Components of the compounds are in a definite ratio, which is fixed by the nature We cannot change this ratio, no matter who does it For example, water is made up of one part oxygen and two parts hydrogen This ratio is fixed by the nature and we cannot alter this Compounds are formed by chemical reactions, where the individual elements lose their individual properties and take on the new properties of the compound that is formed Compounds can be separated into elements using chemical methods but not the physical methods A mixture is a physical combination of two or more substances where the substances retain their original identity Some examples are air, milk, various fruit drinks The most important aspect of the mixture is that it has no definite or constant composition, Mixtures can be separated into pure Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh substances by physical methods Mixture is further classified as either homogeneous or heterogeneous based upon its uniformity A homogeneous mixture is a solution that has a uniform consistency throughout, for example, a salt solution after dissolving and mixing it thoroughly Not only that but also the individual components cannot be identified A heterogeneous mixture does not have uniform composition like homogeneous mixture where the individual components can be identified, for example, a mixture of sand and salt The scheme that classified matter into elements, compounds and mixtures is summarized in figure Figure A classification scheme for matter I Comprehension questions What is chemistry?  Chemistry is the science that deals with the composition and properties of various forms of matter Why is water an object of matter?  Because water occupies space and has mass What is water made up of?  Water is made up of hydrogen and oxygen What is the difference between an element and a compound? Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh An element is a substance composed of a single type of atom while a compound is the substance formed by two or more element chemically combined What is a molecule defined as?  A molecule is the smallest entity having the same proportions of the constituent atoms as does the compound as a whole What is the difference between homogeneous and heterogeneous mixtures?  A homogeneous mixture has a uniform consistency throughout while a heterogeneous mixture does not have uniform composition Which kind of matter has uniform composition?  Pure substance has uniform composition What are the building blocks of the elements?  The building blocks of the elements are the atoms Why is chlorine called a diatomic element?  Because chlorine contains two atoms in its molecules 10 Which kind of matter can be separated by physical methods?  Mixture can be separated into substances by physical methods II No True (T) or false (F) or not mentioned (N) statements T/F/N Statements A substance is a type of matter that has a consistent composition Elements are substances that are made up of two or more elements chemically combined Whereas a compound is made from the chemical combination of two or more substances, a mixture is made from two or more substances that are physically combined Heterogeneous mixtures are mixtures that have a consistent, or uniform composition throughout the entire sample Unlike in the example of compounds, the substances that make up a Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh mixture not lose their individual properties The individual substances in a mixture not lose their original properties, and the substances in a mixture can be separated by physical means When the compound is formed, altogether a new substance is formed and the properties of which are similar to its constituent elements All mixtures have a variable composition, it means that the substances that are found in the mixture can be mixed in with varying proportion or concentrations Chemical reactions can break more complex substances down into elements, but elements can only be broken down further by nuclear reactions 10 Oxygen is a substance because it has a consistent composition and it is an element because it is only made up of one type of atom III Translation Translation 1 Các nguyên tố phân loại thành hai nhóm – kim loại phi kim Elements can be classified into two major groups – metals and nonmetals Phân tử nhóm gồm hai hay nhiều nguyên tử mà liên kết cách hóa học với A molecule is a group of two or more atoms that are chemically combined Hợp chất tạo nguyên tố khác liên kết cách hóa học với theo tỉ lệ xác định A compound is made up of different elements chemically combined in a fixed ratio Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh Các ion tích điện dương hình thành nguyên tử electron A positively charged ion is formed when an atom loses electrons Nhiệt sử dụng để phá vỡ hợp chất thành hợp chất đơn giản nguyên tố Heat can be used to break down compounds into elements or simpler compounds Các thành phần hỗn hợp trộn lẫn với theo tỷ lệ The components of a mixture can be mixed in any proportion Một số chất nguyên chất, giống bạc, chứa loại chất Some substances, like silver, contain only one kind of matter Hỗn hợp đồng thể chất tan dung môi gọi dung dịch A homogeneous mixture of solute and solvent are called solutions Các dạng đơn giản chất mà phân hủy thành chất đơn giản gọi nguyên tố Simple forms of matter which cannot be decomposed into further simple substances are called elements 10 Hợp chất sắt lưu huỳnh sắt sunfua A compound of iron and sulfur is iron sulf ide Translation Petroleum is a very complex mixture that we extract from the Earth Xăng dầu hỗn hợp phức tạp mà chiết xuất từ Trái Đất Colloids are the heterogeneous mixture of two or more components with the size of the particle is 1nm to 100nm Các chất keo hỗn hợp dị thể hai hay nhiều thành tố với kích thước hạt từ 1nm đến 100nm A mixture of two components that appears in a single phase is called a homogeneous mixture Một hỗn hợp hai thành tố tồn pha gọi hỗn hợp đồng thể Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh 54 These elements were given the name "alkali" because they react with water to form hydroxide ions, creating basic solutions (pH>7), which are also called alkaline solutions 55 137Cs undergoes high-energy beta decay and eventually becomes stable barium-137 56 The alkaline earths Ca, Sr, and Ba and the lanthanides Eu and Yb also dissolve in liquid ammonia to give solvated electrons 57 Special precautions must be taken to prevent the alkali metals from coming into contact with water 58 Sodium and potassium, are essentialfor human life 59 Partly due to their large atomic radii and low ionization energies, alkali metals are among the most reactive metals 60 Alkali metals form multiple types of oxides, peroxides and superoxides when combined with oxygen III.2 Translate into English 61 Dung dịch kim loại kiềm amoniac có tính khử mạnh Solutions of alkali metals in liquid ammonia are excellent reducing agents 62 Arfvedson người nhận giống độ tan hợp chất Liti Natri Arfvedson was the first one who recognized similarities between the solubilities of compounds of lithium and those of sodium 63 Các kim loại kiềm giống tính chất hoá học The alkali metals are very similar in their chemical and physical properties 64 Phản ứng natri oxy phản ứng toả nhiệt Reaction betwen sodium and oxygen is exothermic 65 Liti florua halide kim loại kiềm không tan nước Lithium fluoride is the only alkali metal halide that is not soluble in water 66 Các kim loại kiểm thường đựng dầu trơ để tránh bị oxi hoá 29 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh Alkali metals are ordinarily stored under nonreactive oil to prevent oxidation 67 Muối Natri clorua dùng mùa đông để hạn chế lượng tuyết đường Sodium chloride is used during winter months to control the ice on the road 68 Các kim loại kiềm phản ứng mãnh liệt với nước tạo bazo mạnh khí Hidro Alkali metals and water react violently to form strong bases and hydrogen gas 69 Liti thường dùng pin tự sạc được, bao gồm loại pin dùng điện thoại cá nhân, máy quay phim, máy tính xách tay Lithium is often used in rechargeable batteries, including those used in cell phones, camcorders, laptop computers 70.Tất kim loại kiềm có hoạt tính cao khơng tìm thấy dạng nguyên tố tự nhiên All the alkali metals are highly reactive and are never found in elemental forms in nature extra questions 71 Kim loại kiềm phản ứng với halogen tạo muối ion Alkali metals react with halogens to form ionic salts 72 Tất kim loại kiềm nguyên tố hoạt động mạnh khơng tìm thấy dạng ngun tử tự nhiên All the alkali metals are highly reactive and are never found in elemental forms in nature 73 Francium có chu kì bán hủy ngắn phân giã nhanh Francium has a very short half-line (lifetime) and decays quickly 74 Các kim loại kiềm có lửa màu sang nên hữu dụng sản xuất pháo hoa 30 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh The alkali metals' bright flame colors make them useful in firework manufacturing 75 Natri clorua sử dụng nhiều tháng mùa đơng để điều hịa tuyết (hay đã) đường Sodium chloride is used during winter months to control the ice on the road 76 Kim loại kiềm mơ tả có tình mềm màu ánh bạc Alkali metals are characterized by their soft texture and silvery color IV Futher Reading Sodium Why is everyone so concerned about sodium these days? It’s an essential nutrient that the body uses to control blood pressure and blood volume It is also needed for our muscles and nerves to work properly Sodium occurs naturally in most foods The most common form of sodium is sodium chloride, which is table salt Milk, beets, and celery also naturally contain sodium, as does drinking water, although the amount varies depending on the source Sodium is also added to various food products Some of these added forms are monosodium glutamate, sodium nitrite, sodium saccharin, baking soda (sodium bicarbonate), and sodium benzoate These found in items such as soy sauce, onion salt, garlic salt, and bouillon cubes Processed meats, such as bacon, sausage, and ham, and canned soups and vegetables are all examples of foods that contain added sodium Fast foods are generally very high in sodium Taking too much sodium in the diet may lead to high blood pressure in some people or a serious build-up of fluid in people with congestive heart failure, cirrhosis, or kidney disease Therefore, healthy adults should limit sodium intake to 2,300 mg per day Adults with high blood pressure should have no more than 1,500 mg per day Those with congestive heart failureand kidney disease may need much lower amounts 31 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh BÀI 5: ANKANES I Reading Comprehension General notes about alkanes Alkanes are composed of only carbon atoms and hydrogen atoms and contain only single bonds Alkanes in which the carbons form a continuous chain with no branches are called straight-chain alkanes The names of several straight-chain alkanes are given in the table below Alkanes are widespread both on Earth and on other planets The atmospheres of Jupiter, Saturn, Uranus, and Neptune contain large quantities of methane the smallest alkane, which is an odorless and flammable gas In fact, the blue colors of Uranus and Neptune are due to methane in their atmospheres Alkanes on Earth are found in natural gas and petroleum, which are formed by the decomposition of plant and animal materials that have been buried for long periods in the Earth’s crust, an environment with little oxygen Natural gas and petroleum, therefore, are known as 32 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh fossil fuels Natural gas consists of about 75% methane The remaining 25% is composed of small alkanes such as ethane, propane, and butane Petroleum is a complex mixture of alkanes and cycloalkanes that can be separated into fractions by distillation The family of alkanes shown in the table is an example of a homologous series A homologous series (homosis Greek for “the same as”) is a family of compounds in which each member differs from the next by one methylene group The members of a homologous series are called homologs Propane and butane are homologs If you look at the relative numbers of carbon and hydrogen atoms in the alkanes listed in the table above, you will see that the general molecular formula for an alkane is CnH2n+2, where n is any integer We have seen that carbon forms four covalent bonds and hydrogen forms only one covalent bond This means that there is only one possible structure for an alkane with molecular formula CH4 (methane) and only one structure for an alkane with molecular formula C2H6 (ethane) There is also only one possible structure for an alkane with molecular formula C3H8 (propane) As the number of carbons in an alkane increases beyond three, the number of possible structures increases There are two possible structures for an alkane with molecular formula C4H10 In addition to butane—a straightchain alkane—there is a branched butane called isobutane Compounds such as butane and isobutane that have the same molecular formula but differ in the 33 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh order in which the atoms are connected are called constitutional isomers— their molecules have different constitutions There are five constitutional isomers with molecular formula C6H12 We are now able to name three of them (hexane, isohexane, and neohexane), but we cannot name the other two without defining names for new structural units (for more detail, see Further Reading part) Chemical properties of alkanes Alkanes have only strong σ bonds Because the carbon and hydrogen atoms of an alkane have approximately the same electronegativity, the electrons in the C-C and C-H bonds are shared equally by the bonding atoms Consequently, none of the atoms in an alkane have any significant charge This means that neither nucleophiles nor electrophiles are attracted to them Because they have only strong bonds and atoms with no partial charges, alkanes are very unreactive compounds Their failure to undergo reactions prompted early organic chemists to call them paraffins, from the Latin parum affinis,which means “little affinity”(for other compounds) Alkanes react with chlorine or bromine to form alkyl chlorides or alkyl bromides These halogenation reactions take place only at high temperatures or in the presence of light (symbolized by hυ) They are the only reactions that alkanes undergo—with the exception of combustion, a reaction with oxygen that takes place at high temperatures and converts alkanes to carbon dioxide and water 34 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh The mechanism for the halogenation of an alkane is well understood The high temperature (or light) supplies the energy required to break the Cl-Cl or Br-Br bond homolytically Homolytic bond cleavage is the initiation step of the reaction because it creates the radical that is used in the first propagation step Recall that an arrowhead with one barb signifies the movement of one electron A radical (often called a free radical) is a species containing an atom with an unpaired electron A radical is highly reactive because it wants to acquire an electron to complete its octet In the mechanism for the monochlorination of methane, the chlorine radical formed in the initiation step abstracts a hydrogen atom from methane, forming HCl and a methyl radical The methyl radical abstracts a chlorine atom from forming methyl chloride and another chlorine radical, which can abstract a hydrogen atom from another molecule of methane These two steps are called propagation steps because the radical created in the first propagation step reacts in the second propagation step to produce a radical that can repeat the first propagation step Thus, the two propagation steps are repeated over and over The first propagation step is the rate determining step of the overall reaction Because the reaction has radical intermediates and repeating propagation steps, it is called a radical chain reaction 35 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh I.1 Questions An organic compound is classified as an alkane if it satisfies which cretaria? ………………………………………………………………………………… How many kinds of alkanes are there if we classify them basing on their carbon chains? What are they? ………………………………………………………………………………… How were alkanes on Earth formed? ………………………………………………………………………………… What are the main components of natural gas? ………………………………………………………………………………… What is the general molecular formula for the homologous series of alkanes? ………………………………………………………………………………… Why alkanes with higher number of carbons have more constitutional isomers than those with fewer carbons? ………………………………………………………………………………… Why are ankanes so unreactive? ………………………………………………………………………………… Under which conditions can alkanes be halogenated? 36 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh ………………………………………………………………………………… What is the rate determining step of the overall radical halogenation reaction of alkanes? ………………………………………………………………………………… 10 What is the general characteristics of a radical reaction? ………………………………………………………………………………… I.2 TRUE (T), FALSE (F) and UNKNOWN statements No Answer Statements  Compounds that contain only carbon and hydrogen are called hydrocarbons, so an alkane is a hydrocarbon that has only single bonds  Alkanes can have only the straight carbon chains  Alkanes on Earth were formed under anaerobic conditions  Natural gas is considered as a fossil fuel as its components burn easily, accompanied by releasing of high amount of heat  All alkanes have even numbers of hydrogens  The higher the number of carbons in an alkane, the greater the number of possible constitutional isomers it has  Alkanes have very low affinity with various reagents since they have only strong non-polar single bonds  Alkanes react with chlorine or bromine to form alkyl chlorides or alkyl bromides These halogenation  37 Alkanes can react with halogens to form alkyl halides when Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh being heated or radiated with light of suitable wavelenghts  10 When a mixture of an alkane and a halogen are heated at high temperature or radiated with light, the C-C and C-H are homolytically cleaved at the initiation step I.3 Fill in each blank with one suitable word: 122 attraction electrons share reacts nucleophile electrophile reactivity functional accept electron-rich In essence, organic chemistry is about the interaction between (1)……………………….atoms or molecules and electron-deficient atoms or molecules It is these forces of (2)………………… that make chemical reactions happen From this follows a very important rule that determines the (3)…………………… of organic compounds: Electron-rich atoms or molecules are attracted to electron-deficient atoms or molecules Each time you study a new (4)……………………… group, remember that the reactions it undergoes can be explained by this very simple rule Therefore, to understand how a functional group reacts, you must first learn to recognize electron-deficient and electron-rich atoms and molecules An electrondeficient atom or molecule is called an (5)……………………… An electrophile can have an atom that can (6)……………………… a pair of electrons, or it can have an atom with an unpaired electron and, therefore, is in need of an electron to complete its octet Thus, an electrophile looks for (7)…………………… Literally,“electrophile” means “electron loving” (phileis the Greek suffix for “loving”) 38 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh An electron-rich atom or molecule is called a (8)……………………… A nucleophile has a pair of electrons it can (9)………………… Some nucleophiles are neutral and some are negatively charged Because a nucleophile has electrons to share and an electrophile is seeking electrons, it should not be surprising that they attract each other Thus, the preceding rule can be restated as a nucleophile (10)…………………… with an electrophile Because an electrophile accepts a pair of electrons, it is sometimes called a Lewis acid Because a nucleophile has a pair of electrons to share, it is sometimes called a Lewis base II Grammar Complete the following sentences using suitable form of comparison If (many)…………………… one substituent is attached to the parent hydrocarbon, the chain is numbered in the direction that will result in (low)…………………… possible number in the name of the compound When both directions lead to the same (low)……………… number for one of the substituents, the direction is chosen that gives (low)……………… possible number to one of the remaining substituents 39 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh If the same substituent numbers are obtained in both directions, the first group cited receives the (low) ………… number If a compound has two or (much)………………… chains of the same length, the parent hydrocarbon is the chain with (great)………………… number of substituents When there is only a substituent, the substituent gets (low)……………… possible number When there is only a functional group suffix, the functional group suffix gets (low)………………… possible number When there is both a functional group suffix and a substituent, the functional group suffix gets (low)……………… possible number An alkyne is (reactive)……………………… an alkene This might at first seem surprising because an alkyne is (stable)……………………… an alkene (see figure below) However, reactivity depends on ∆G‡ which in turn depends on the stability of the reactant and the stability of the transition state For an alkyne to be both (stable) and (reactive)……………… an alkene, two conditions must hold: The transition state for the first step (the rate-limiting step) of an electrophilic addition reaction for an alkyne must be (stable)……………… the transition state for the first step of an electrophilic addition reaction for an alkene 40 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh Allylic and benzylic cations have delocalized electrons, so they are (stable)………………… similarly substituted carbocations with localized electrons Side-to-side overlap of in-phase p orbitals (lobes of the same color) produces a bonding molecular orbital The bonding molecular orbital is (low)…………… in energy …………… the p atomic orbitals, and it encompasses both carbons In other words, each electron in the bonding molecular orbital spreads over both carbon atoms Side-to-side overlap of outof-phase p orbitals produces an antibonding molecular orbital, which is (high)………… in energy ……… the p atomic orbitals We must also be aware that bromination is a much (slow)…………… reaction …………… chlorination The activation energy for abstraction of a hydrogen atom by a bromine radical has been found experimentally to be about 4.5 times greater than that for abstraction of a hydrogen atom by a chlorine radical 41 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh 10 The fluorine radical is (reactive)……………………… of the halogen radicals, and it reacts violently with alkanes In contrast, the iodine radical is (reactive)………………… of the halogen radicals III Translation III.1 Translate the following text into Vietnamese The description of the step-by-step process by which reactants (e.g., alkene + HBr) are changed into products (e.g., alkyl halide) is called the mechanism of the reaction To help you understand a mechanism, curved arrows are drawn to show how the electrons move as new covalent bonds are formed and existing covalent bonds are broken In other words, the curved arrows show which bonds are formed and which are broken Because the curved arrows show how the electrons flow, they are drawn from an electronrich center (at the tail of the arrow) to an electron-deficient center (at the point of the arrow) An arrowhead with two barbs represents the simultaneous movement of two electrons (an electron pair) An arrowhead with one barb represents the movement of one electron These are called “curved” arrows to distinguish them from the “straight” arrows used to link reactants with products in chemical reactions III.1 Translate the following text into English Các yếu tố ảnh hưởng đến tỉ lệ sản phẩm Các gốc ankyl ổn định hóa nhóm ankyl đẩy electron, vậy, gốc ankyl bậc III bền gốc ankyl bậc II, gốc ankyl bậc II bền gốc ankyl bậc I 42 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh Gốc tự bền vững dễ hình thành, độ bền gốc ankyl tự thể độ bền trạng thái chuyển tiếp dẫn đến tạo thành gốc Kết là, việc tách nguyên tử H dẫn đến tạo thành gốc bậc II dễ dàng tách H dẫn đến tạo thành gốc tự bậc I Để xác định hàm lượng tương đối sản phẩm tạo thành phản ứng clo hóa ankan, cần tính đến hai yếu tố xác xuất (số lượng nguyên tử H loại bị tách để dẫn đến hình thành sản phẩm đó) khả phản ứng (tốc độ tương đối tách nguyên tử H) Khi hai yếu tố tính đến hàm lượng theo tính tốn phù hợp với lượng thu từ thực nghiệm 43 Tài liệu tập huấn giảng viên dạy chuyên ngành tiếng Anh