Ch2. Atoms, Molecules and Ions

Transcription

1 Ch2. Atoms, Molecules and Ions The structure of matter includes: (1)Atoms: Composed of electrons, protons and neutrons.(2.2) (2)Molecules: Two or more atoms may combine with one another to form an uncharged molecule. 分子內鍵結 :Covalent bond 共價鍵分子分子間 : 一般通稱 van der Waals force of Hydrogen bon (3)Ions: spices of opposite charge found in all ionic compounds.

2 2.1 Atoms and the Atomic Theory 2.2 Components of the Atom 1. Electrons 2.Portons and Neutrons;The Atomic nucleus 3. Atomic Number 4.Mass numbers;isotopes 5.Nuclear Stability;Radioactivity 2.3 Introduction to the Periodic Table 1. Periods and Groups 2. Metals and Nonmetals 2.4 Molecules and Ions 1. Molecules(molecular structural condensed structural formula) 2. Ions(cations,anion, ionic bond,strong electrolyte, nonelectrolytes ) 2.5 Formulas of Ionic Compounds 1. Cations and Anions with Noble gas Structures 2. Cations of the Transition and Post Transition Metals 3. Polyatomic Ions 2.6 Names of Compounds 1. Ions 2. Ionic Compounds 3. Binary Molecular Compounds 4. Acids

3 2-1 Atoms and the Atomic theory. John Dalton:atomic model of matter( in 1808) (1) An element is composed of tiny particles called atoms. (2)In ordinary chemical reaction, atoms move from one substance to another, but no atom of any element disappears or is changed into an atom of another element. (3)Compounds are formed when atoms of two or more elements combine, and the relative numbers can be expressed as integers or simple fractions. 同素異形體

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5 Dalton s atomic theory can explain three basic laws of chemistry: law of conservation of mass 質量不滅 There is no detectable change in mass in an ordinary chemical reaction. 化學反應的前後, 參與反應的物質性質改變, 質量永遠沒有改變 law of constant composition 定比定律, 2 個 H 一個 O A compound always contains the same elements in the same proportions by mass. 在相同化合物的不同樣品中, 始終含有相同質量比的組成元素 law of multiple proportions 倍比定律. Two elements form more than one compound. The masses of one element that combine with a fixed mass of the second element are in a ratio of small whole numbers. 兩元素形成兩種以上的化合物, 若將其中一元素的質量固定, 另一元素的質量將成一簡單整數比

6 2-2 Components of the atom 1897 年,J. J. Thomson 於利用陰極射線管發現電子 1911 年,Ernest Rutherford 於利用 α 粒子撞擊黃金薄片發現質子 1932 年,Chadwick 從事核反應發現中子

7 electron 1897 年,J. J. Thomson that the cathode rays consist of a stream of negatively charged 原子最外圍之微小粒子, 為第一個被發現之次原子粒子 在原子核外一段距離的位置 Carry a unit negative charge (-1) mass g, 約為質子的 1/2000

8 Figure2.3 A cathode ray passing through an electric field

9 Cathode ray 陰極射線實驗 陰極射線為帶負電之粒子 可利用此裝置測出陰極射線的電荷與質量之比 e m = 庫侖克

10 油滴實驗 測出電子的電量為 庫侖 配合湯木生已測得的電子荷質比 庫侖 / 克 算出電子的質量為 克

11 Proton( 質子 ) and neutron( 中子 ) Proton: Rutherford 以 α 粒子撞擊氮原子而發現 Which has a mass nearly equal to that of an ordinary hydrogen atom 1911 年,Ernest Rutherford The proton carries a unit positive charge(+1),equal in magnitude to that of the electron(-1). 電荷質量約為 g He+ 7N 8O+ 中子 : 查兌克以 α 粒子撞擊鈹原子而發現 An uncharged particle with a mass slightly greater than that of a proton. 不帶電. 質量略大於質子, g 位於原子核 Because protons and neutrouns are much heavier than electrons, most of the mass of an an atom is concentrated in the nucleus 1 1 p He+ 4Be 6O+ 1 0 n

12 Protons and Neutrons Fig2.4 Rutherford's α particle scattering experiment.

13 α 粒子散射實驗 拉塞福由 α 粒子散射實驗提出 : 原子是由原子核與電子所組成 原子核帶正電荷為原子質量所在, 電子在核外繞核運動

14 α 粒子散射的成因

15 原子的結構與組成 amu = g = g 原子直徑 m m = 1 amu = p n 1836m e 原子核直徑 質量電量 發現次序 發現者 位 置 電子 (electron) 克 庫侖 1 湯木生 核外 質子 (proton) 克 庫侖 2 拉塞福 核內 中子 (neutron) 克不帶電 3 查兌克 核內

16 Atom and Atom nucleus 假設氫原子的直徑如棒球場之直徑, 則原子核的大小就如一隻螞蟻

17 Atomic number ( Z 原子序 ) In a neutral atom, the number of protons in the nucleus. For neutral atom: H atom: 1 proton 1 electron Z = 1 U atom: 92 protons 92 electrons Z = 92 Mass Number, A = Number of protons + number of neutrons 質量數 A X 元素符號 原子序 Z Number of neutrons =A-Number of protons

18 Atomic Number and Mass Numbers Mass Numbers=protons+neutron A Z X Na 原子序為 11, 質量數為 23 表示有 11 個質子,11 個電子 而中子數 =23-11 =12 Atomic number=protons= 中性原子之 electrons Isotopes 同位素 : 原子序 (Z) 相同但質量數 (A) 不同之元素 1 1 H( 氫 ) 2 1 H( 氘, 亦稱為重氫, 可記為 D)

19 (Atomic number) and (Mass number) 相等於 電子的數目 相等於 故 原子不帶電荷 atoms 內的 質子的數目 不一定相等 中子的數目 稱為 的總和 原子序 (atomic number) 質量數 (mass number)

20 Isotopes: 同位素 Atoms that have the same number of protons but different numbers of neutrons are called isotopes Atomic number (Z) = number of protons

21 Isotopes Isotope Z A Number of protons Number of Neutrons Uranium Uranium

22 同素異形體 立體網狀 平面層狀 球面 同素異形體 : 同一原子所組成的物質, 因結構或空間的排列不同, 性質亦不同

23 Ex 2-1: (a)an isotope of cobalt (Co,Z=27 )is used in radiation therapy for cancer. This isotope has 33 neutrons in its nucleus. What is its nuclear symbol? (b)one of the most harmful components of nuclear waste 90 is radioactive isotope of strontium 38Sr;it can be deposited in your bones. Where it replaces calcium. How many protons are in the nucleus of Sr-90?How many neutrons? sol a) Co: Z = 27, has 33 neutrons Co b) proton:38 鍶 : neutron:90 38 =

24 Nuclear Stability ; Radioactivity The neutron to-proton ration required for stability varies with atomic number. For light elements Z < 20 穩定帶 (this ratio is close to 1) As atomic number increase, Z 1.5 the belt of stability shifts to higher numbers of neutrons. 106 Pb (260-82)=124/82=1.51 C 10 6 C 11 6 C 12 6 C 13 6 C 14 6 C 15 6 C 16 6 C

25 Figure 2.5 Neutron-to proton rations of stable isotopes.

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27 2-3 Introduction to the Periodic Table Periodic table of elements 1. chemical property of arranging the element of electron are to depend on the most outer electronic figure of atom. ( 化學性質與電子排列元素的化學性質是取決於原子最外層電子數目 ) 2.Classified the element for 1869 years, Russian chemical favorable of door victory made the periodic table of elements. 3.In the periodic table of elements, all elements are arranged to the great order small in accordance with the atom preface. ( 在元素週期表內, 所有元素都依原子序由小至大順序排列

28 Group 族 原子序 電子排佈 週期 鹼金屬 鹼土金屬 過渡元素 鹵素 惰性氣體 主族 過渡 半金屬 非金屬 金屬 金屬 氣體液體固體 主族

29 Periodic Table Group 族 : The vertical columns main-group elements : 1,2,13,14,15,16,17,18 Transition Metals: group 3 through 12 Post-transition Metals : 13,14,15 元素的族數 = 其原子最外層電子殼上的電子數目 同族元素有相同的最外層電子殼電子數目, 故化學性質甚為相似

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31 Periodic Table Period The horizontal rows in the table -The first period consists of the two elements hydrogen - 週期表中的橫排稱為週期, 共有 7 個週期 - 元素的週期數目 = 原子內被電子佔用的電子殼層數

32 同週期元素性質的規律 Metals and Nonmetals There is a stairway that starts to the left of boron in the periodic table separates meats from nonmetals. Elements around the line are referred to as metalloids 同一週期內元素的類別由左至右漸變 由金屬 半金屬 非金屬 分界線

33 固態 碳 鋁 Subst ance 組成的單位是 可分類為 元素 有三個形態 液態 氣態 汞 溴 氫 氧 金屬 (86 種 ) 半金屬 (7 種 ) 非金屬 (16 種 )

34 第 I 族元素 ( alkali metal 鹼金屬 ) (Li) (Na) (K) (Rb) (Cs) 和 (Fr) 密度較水低 低沸點 活性由上至下漸增 活潑金屬 低熔點 軟金屬 物理特性 鹼金屬 化學特性 形成帶一個正電荷的陽離子 與非金屬反應生成鹽 化合物全是可溶於水的白色晶體

35 2 group element( alkaline earth metal ) Be, Mg, Ca, Sr, Ba, 密度較水高 低沸點 活性由上至下漸增 活潑金屬 低熔點 物理特性 鹼土金屬 化學特性 形成帶兩個正電荷的陽離子 族中位置較低的元素才能與冷水產生反應 與非金屬反應生成鹽 活性次於第 I 族

36 第 17 族元素 ( halogen 鹵素 ) F, Cl, Br, I, At, 狀態由上至下依次漸變 活性由上至下漸降 除了碘之外全都有毒, 並有特殊氣味 物理特性 鹵素 化學特性 以雙原子分子的形式存在 非金屬 形成帶一個負電荷的陰離子 與金屬反應生成鹽

37 2-4 Molecules and Ions Isolated atoms rarely occur in nature only the noble gases. Atoms tend to combine with one another in various ways to form more complex structural units. molecules and ions. 1.Molecules: Two or more atoms may combine with one another to form an uncharged molecule Nonmetallic element + nonmetallic element Intramolecular force covalent bonds Bond strength > 50 Share pairs of electrons Ti O:160 Intermolecular force: 分子分子間作用力 van Der Waals force

38 Expression method 化合物化學式 Experiment type Molecular formula Structural formula Condensed structural formula Acetic acid CH 2 O C 2 H 4 O 2 CH 3 COOH Remarks Can express it in molecules, the kind of the atom and looks contrast value of the atomicity Can show the kind of the atom and figure of real atom Can show atom kind, figure and combine the situation Can show atom kind, figure and sense base included in molecules, but show its molecule characteristic simply

39 Example2.0 Give the molecular formulas of (a) ethyl alcohol and (b) ethylamine. Sol: (a) C 2 H 6 O (b) C 2 H 7 N

40 2. Ions When an atom loses or gains electrons,charged particles called ions are formed Metal atoms typically tend to lose electrons to from positively charge ions called cations. How Cause? Ions When an atom loses or gains electrons loses gains Cations (Metal) Anions (nonmetal) Na 失去 1 個電子 Na + xx xx x x x x x Cl x xx xx 獲得 1 個電子 xx xx x x x x x Cl x x xx - 鈉原子 鈉離子 x x x x 氯原子 x x x x 氯離子

41 Example 2.3 :Give the number of protons, neutrons and electrons?(a) (b) Sol : (a) P e + : 13 : 13 3 = n : = 16 S 13 Al (b) P + : 16 e : = 18 n : = 16

42 Monatomic :They are derived from a single atom by the loss or gain of electrons. e.g, Na +,Cl - Polyatomic: Containing more than one atom. as a Charged molecule. ex: OH -,(O-H) - (NH 4 ) ++ Ionic compound are held together by strong electrical forces between oppositely charged ions. These forces are referred to as ionic bonds

43 2-5 Formulas of ionic compounds When a metal reacts with a nonmetal such( Na,Cl) the product is an ionic compound. simplest ratio between cation and anion The total positive charge of the cations in formula must equal the total negative charge of the anions 1.Cations and Anions with Nobel-gas structure Atoms that are close to a noble gas (group 18) in the periodic table form ions that contain the same number of electrons as the neighboring noble-gas atoms

44 group No.of Electrons in atom Charge of ion formed Examples 1 1 more than noble gas +1 Na more than noble gas +2 Mg less than noble gas -2 O less than noble gas -1 F - Al 3+ (Al has three more e - than the preceding noble gas,ne) N 3- (N has three fewer e- than the preceding noble gas,ne)

45 2.Cations of the transition and post-transition metals (1).Transition metals in group 3-12 (2).The post- transition metals in groups13-15 The cat ions formed by these metals typically have charges of +1,+2,or +3 and ordinarily do not have noble-gas structures. Many of the transition and post-transition metals form more than one cat ion. iron is present as a +2 Cation Fe 2+ : FeCl 2, FeBr 2 +3 Cation Fe 3+ : FeCl 3,FeBr 3 p41

46 polyatomic ion( 多原子離子 ) There are only two common polyatomic cat ions NH 4+,Hg 2 2+ All other cat ion Considered in this text are derived from individual metal atoms Most of the polyatomic anion contain one or more oxygen atoms; collectively these species are called oxoanions.

47 Example2.5: Predict the formula of the compound : (a) Formed by barium with iodine. (b) (c) (d) (Ba +2 )+2(I - ) BaI 2 aluminum 鋁與 oxide 作用 2(Al +3 ) + 3 (O -2 ) Al 2 O 3 Containing Cu +2 及 oxide ion Cu +2 + O -2 CuO Containing Cu + and oxide ions 2(Cu + ) + O -2 Cu 2 O

48 2.6 Names of Compounds A compound can be identified either by its formula (e.g.nacl) or by its name ( sodium Chloride) Table2.3 Oxoanions of Nitrogen,sulfur,and Chlorine Nitrogen No 3 - nitrate NO 2 - nitrite Sulfur SO 4 2- Sulfate SO 3 2- Sulfite Chlorine ClO - 4 Perchlorate ClO - 3 Chlorate ClO - 2 Chorite ClO - Hypochorite

49 2.6 Names of Compounds ions monatomic 單原子離子 Polyatomic 多原子離子 ions compounds Binary Molecular Compound

50 Monatomic ions Monatomic ions: 可直接由金屬本身的名稱加以延伸 Cations: 直接由金屬本身的名稱加延伸 ium Na + : Sodium,K + : Potassium Transition and post-transition of ions: 將電荷數直接以羅馬數字表示在後, 英文命名則以 字尾 ic 代表為高電荷離子 Fe +3 iron (III),Ferric 字尾 ous 代表為低電荷離子 Fe +2 iron(ii),ferrous Anions : 前半段是以非金屬名稱為主, 字尾以 ide 結束 P42

51 polyatomic ion Most of the polyatomic anions contain one or more oxygen atoms: collectively these species are called oxoanions OH -,CO When a nonmetal froms two oxoanions, the suffix 字尾 ate,is used for the anion with the larger number of oxygen atoms. 字尾 ite, 代表含有較低數目氧原子 常見多原子離子 當非金屬形成 2 個以上含氧陰離子 則字首為 per, 含最大氧原子數目的離子, 字首為 hypo-, 則為含有最小氧原子數目的離子 表 2.3 氮 硫及氯的含氧陰離子

52 Ionic compounds Metal 中英文的方式剛好相反 NaCl 氯化鈉 Sodium chloride CaS 硫化鈣 Calcium sulfide Transmation metal 將其電荷數以羅馬數字表示 Cr(NO 3 ) 3 硝酸鉻 Chromium (III) nitrate

53 Example2.6: Name the following ionic compound: (a) CaS (b) Al(NO 3 ) 3 FeCl 2 Sol: (a) CaS Calcium sulfied (b) (b) Al(NO 3 ) 3 aluminum nitrate (c) FeCl 2 Iron (II) chloride

54 Binary compound 二元分子化合物 When two nonmetals combine with each other,theproduct is most often a binary molecular compound. 1.The first word gives the name of the element that appears first on the fromula:greek Prefix (table2.4) 2(di) 3(tri) 4(tetra) 5(penta) 6 (hexa) 7( hepta) 8 (octa) 9 (nona) 10(deca) 2.The second word consists of The stem of the name of the second element The suffix ide 結尾

55 To illustration these rules, consider the names of the several acides of nitrogen N 2 O 5 Dinitrogen pentaoxide 五氧化二氮 N 2 O 3 Dinitrogen trioxide N 2 O 4 Dinitrogen tetraoxide NO Nitrogen oxide NO 2 Nitrogen dioxide N 2 O Dinitrogen oxide 三氧化二氮 四氧化二氮 一氧化氮 二氧化氮 一氧化二氮

56 Ex:2.7 Give the names (a) SO 2 Sulfur dioxide ( 二氧化硫 ) (b) SO 3 Sulfur trioxide ( 三氧化硫 ) (c) PCl 3 Phosporus trichloride ( 三氯化磷 ) (d) Cl 2 O 7 Dichlorines heptaoxide ( 七氧化二氯 )

57 Common names H 2 O 水 Water H 2 O 2 雙氧水 ( 過氧化氫 ) Hydrogen peroxide NH 3 氨 Ammonia N 2 H 4 肼 Hydrazine C 2 H 2 乙炔 Acetylene PH 3 磷化氫 Phosphine AsH 3 砷化氫 Arsine NO 氧化氮 Nitric oxide N 2 O 氧化亞氮 Nitrous oxide CH 4 甲烷 Methane

58 Acid It containing H atoms ionize in water to form H + ions 純物質 水溶液 HCl Hydrogen chloride H +,Cl - Hydrochloric acid HBr Hydrogen bromide H +,Br - Hydrobormic acid HI Hydrogen iodide H +,I - Hydroiodic acid Most acids contain oxygen in addition to hydrogen atoms as (oxoacids) H 2 CO 3 碳酸 Carbonic acid H 2 SO 4 硫酸 Sulfuric acid HNO 3 硝酸 Nitric acid HClO 3 氯酸 Chloric acid

59 HClO 4 過氯酸 ClO 4 - 過氯酸根 Perchloric acid Perchlorate HClO 3 氯酸 ClO 3 - 氯酸根 Chloric acid Chlorate HClO 2 亞氯酸 ClO 2 - 亞氯酸根 Chlorous acid Chlorite HClO 次氯酸 ClO - 次氯酸 Hypochlorous acid Hypochlorite

60 含氧酸命名法則 含氧酸 (oxoacid) 含氧酸陰離子 oxoanion 過... 酸 per...ic acid 過... 酸根 per...ate 酸 ic 酸根 ate 亞... 酸...ous acid 亞... 酸根...ite 次... 酸 hypo...ous acid 次... 酸根 hypo...ite

61 Ex2.8: Give the names of Sol: (a) HNO 2 亞硝酸 nitrous acid (b) H 2 SO 3 亞硫酸 sulfurous acid (c) HIO 次碘酸 hypoiodous acid