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.

¡ 2.1 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

§ 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

Dalton’s atomic theorycan 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OA 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

§ 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

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)。¡ mass9.11×10-28g，約為質子的1/2000

Figure2.3 A cathode ray passing through an electric field

Cathode ray 陰極射線實驗

Ø陰極射線為帶負電之粒子

Ø可利用此裝置測出陰極射線的電荷與質量之比

克庫侖81076.1

me

×=

油滴實驗

Ø測出電子的電量為1.6×10 -19庫侖

Ø配合湯木生已測得的電子荷質比1.76×10 8庫侖／克算出電子的質量為9.1×10 -28克

Proton(質子) and neutron(中子)

ØProton： 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 atomØ1911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1.672×10-24g

pONHe 11

178

147

42 +→+

Ø中子：查兌克以α粒子撞擊鈹原子而發現

Ø→An uncharged particle with a mass slightly greater than that of a proton.不帶電. 質量略大於質子，1.675×10-24g 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。

nOBeHe 10

126

94

42 +→+

Protons and Neutrons

Fig2.4 Rutherford's α particle scattering experiment.

α粒子散射實驗

Ø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

α粒子散射的成因

原子的結構與組成

質 量 電 量

電子(electron) 9.101╳10－28克 －1.6╳10－19庫侖

質子(proton) 1.673╳10－24克 ＋1.6╳10－19庫侖

中子(neutron) 1.675╳10－24克 不帶電

發現次序

1

2

3

發 現 者

湯木生

拉塞福

查兌克

位 置

核外

核內

核內

原子直徑

原子核直徑

g1067.1g1002.6

1amu 2423

−×=×

=

enp 1836mamu1mm ==≈

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。

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 = 1U 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

Atomic Number and Mass Numbers

XAZ

Mass Numbers＝protons＋neutron

Atomic number＝protons＝中性原子之electrons

Na2311

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

◆Isotopes同位素：原子序(Z)相同但質量數(A)不同之元素。

（氫）、H11 H2

1 （氘，亦稱為重氫，可記為D）

(Atomic number) and (Mass number)

atoms 內的

中子的數目

質子的數目

電子的數目 故

稱為 原子序(atomic number)

相等於 原子不帶電荷

相等於

的總和 質量數(mass number)

不一定相等

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

Isotopes

1469223892Uranium-235

1439223592Uranium-235

Number of NeutronsNumber of protons

AZIsotope

同素異形體

Ø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。

立體網狀

平面層狀

球面

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 is radioactive isotope of strontium ；it can be deposited in your bones. Where it replaces calcium. How many protons are in the nucleus of Sr-90？How many neutrons？

sola) Co： Z = 27, has 33 neutronsb) proton：38 鍶： neutron：90 – 38 = 52

Co6027

Sr9038

§ 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.

¡

¡ (260-82)=124/82=1.51

CCCCCCCC 166

156

146

136

126

116

106

96

Pb10682

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

§ 2-3 Introduction to the Periodic TablePeriodic table of elements

1.1. chemical property of arranging the element of electron chemical property of arranging the element of electron are to depend on the most outer electronic figure of are to depend on the most outer electronic figure of atomatom. . ((化學性質與電子排列元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)

2.2.Classified the element for 1869 years, Russian chemical Classified the element for 1869 years, Russian chemical favorable of door victory made the favorable of door victory made the periodic table of elements. 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

Group 族

週期

原子序

電子排佈

過渡元素

鹼金屬

鹼土金屬

惰性氣體鹵

素

主族 過渡 半金屬 非金屬金屬 金屬

氣體 液體 固體

主族

¡ Group族 : The vertical columns ô main-group elements : 1,2,13,14,15,16,17,18

ô Transition Metals: group 3 through 12

ô Post-transition Metals : 13,14,15

ô元素的族數 = 其原子最外層電子殼上的電子數目。ô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。

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

Periodic Table

同週期元素性質的規律同週期元素性質的規律

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à半金屬à非金屬。

分界線

Metals and Nonmetals

Substance

組成的單位是 元素

有三個形態

固態

氣態

液態

碳、鋁

汞、溴

氫、氧

可分類為

非金屬(16種)

金屬(86種)

半金屬(7種)

第 I 族元素（ alkali metal 鹼金屬) (Li)、(Na)、(K)、(Rb)、(Cs)和(Fr)

鹼金屬 化學特性物理特性低熔點

低沸點

軟金屬

密度較水低

活潑金屬

活性由上至下漸增

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

2 group element( alkaline earth metal ）Be , Mg , Ca , Sr , Ba ,

鹼土金屬 化學特性物理特性低熔點

低沸點

密度較水高

活潑金屬

活性由上至下漸增

形成帶兩個正電荷的陽離子

與非金屬反應生成鹽

活性次於第 I 族

族中位置較低的元素才能與冷水產生反應

第 17 族元素（ halogen 鹵素）F , Cl , Br , I , At ,

鹵素 化學特性物理特性

非金屬

狀態由上至下依次漸變

以雙原子分子的形式存在

活性由上至下漸降

形成帶一個負電荷的陰離子

與金屬反應生成鹽

除了碘之外全都有毒，並有特殊氣味

§ 2-4 Molecules and IonsIsolated 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

¡

Expression method

Can show atom kind , figure and sense base included in molecules , but show its molecule characteristic simply

Can show atom kind , figure and combine the situation

Can show the kind of the atom and figure of real atom

Can express it in molecules , the kind of the atom and looks contrast value of the atomicity

Remarks

CH3COOH Condensed structural formula

Structural formula

C2H4O2 Molecular formula

CH2O Experiment type

Acetic acid 化學式

化合物

Example2.0 Give the molecular formulas of (a) ethyl alcohol and (b) ethylamine.

Sol:(a) C２Ｈ６Ｏ（ｂ） C２Ｈ７Ｎ

2. Ions

Ions

How Cause?

When an atom loses or gains electrons

gains

loses Cations(Metal)

Anions(nonmetal)

Na

+

失去

1個電子

鈉原子 鈉離子

NaCl

獲得

1個電子Cl

-

氯原子 氯離子

x xx x

x xx x

x xx x

x xx xx x

x xx x

x xx x

x xx x

xx xx x

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.

Example 2.3 ：Give the number of protons, neutrons and electrons？(a) (b)

Sol :(a)

(b)

+32713 Al −232

16 S

141327:10313:

13:

=−=−−

+

neP

161632:18216:

16:

=−=+−

+

neP

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)- (NH4)++

Ionic compound are held together by strong electrical forces between oppositely charged ions.

These forces are referred to as ionic bonds

§ 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 cationand 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 structureAtoms 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

Na++11 more than noble gas1

F--11 less than noble gas17

O2--22 less than noble gas16

Mg2++22 more than noble gas2

ExamplesCharge of ion formedNo.of Electrons in atomgroup

Al3+ (Al has three more e- than the preceding noble gas ，Ne)

N3- (N has three fewer e- than the preceding noble gas ，Ne)

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 CationFe2+: FeCl2， FeBr2

+3 CationFe3+: FeCl3，FeBr3

p41

polyatomic ion(多原子離子)

¡ There are only two common polyatomic cat ionsôNH4

+，Hg22+

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.

Example2.5: Predict the formula of the compound ：(a) Formed by barium with iodine.

(Ba+2)+2(I－)→BaI2(b) aluminum鋁與oxide 作用

2(Al+3) + 3(O－2) →Al2O3

(c) Containing Cu+2及oxide ionCu+2 + O－2 →CuO

(d) Containing Cu+ and oxide ions2(Cu+) + O －2 → Cu2O

§ 2.6 Names of Compounds A compound can be identified either by its formula (e.g.NaCl)

or by its name ( sodium Chloride)

ClO-

Hypochorite

ClO2-

ChoriteSO3

2-

SulfiteNO2

-

nitrite

ClO3-

ChlorateSO4

2-

SulfateNo3

-

nitrate

ClO4-

Perchlorate

ChlorineSulfurNitrogen

Table2.3 Oxoanions of Nitrogen，sulfur，and Chlorine

§ 2.6 Names of Compounds

¡ ionsômonatomic單原子離子ôPolyatomic 多原子離子

¡ ions compounds¡ Binary Molecular Compound

Monatomic ions

¡ Monatomic ions:可直接由金屬本身的名稱加以延伸ôCations：直接由金屬本身的名稱加延伸ium。¡ Na+ : Sodium，K+ : Potassium

ôTransition 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

ôAnions ：前半段是以非金屬名稱為主，字尾以ide結束。ô P42

polyatomic ion¡ Most of the polyatomic anions contain one or more oxygen

atoms: collectively these species are called oxoanionsôOH－，CO3

－2

ô1.When a nonmetal froms two oxoanions， the suffix 字尾–ate ，is used for the anion with the larger number of

oxygen atoms.ô字尾 ite，代表含有較低數目氧原子ô常見多原子離子

¡ 當非金屬形成2個以上含氧陰離子ô則字首為per，含最大氧原子數目的離子,ô字首為hypo-，則為含有最小氧原子數目的離子ô表2.3氮、硫及氯的含氧陰離子

Ionic compounds

¡ Metal¡ 中英文的方式剛好相反ôNaCl 氯化鈉 Sodium chlorideôCaS 硫化鈣 Calcium sulfide

¡ Transmation metalô將其電荷數以羅馬數字表示。

ôCr(NO3)3 硝酸鉻 Chromium (III) nitrate

Example2.6: Name the following ionic compound:(a) CaS (b) Al(NO3)3 © FeCl2

Sol:(a) CaS Calcium sulfied(b) (b) Al(NO3)3 aluminum nitrate(c) © FeCl2 Iron (II) chloride

Binary compound二元分子化合物¡ When two nonmetals combine with each other,the product

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

To illustration these rules, consider the names of the several acides of nitrogen

¡ N2O5 Dinitrogen pentaoxide 五氧化二氮¡ N2O3 Dinitrogen trioxide 三氧化二氮

¡ N2O4 Dinitrogen tetraoxide 四氧化二氮¡ NO Nitrogen oxide 一氧化氮

¡ NO2 Nitrogen dioxide 二氧化氮

¡ N2O Dinitrogen oxide 一氧化二氮

Ex:2.7 Give the names (a) SO2

Sulfur dioxide (二氧化硫)(b) SO3

Sulfur trioxide (三氧化硫)(c) PCl3

Phosporus trichloride (三氯化磷)(d) Cl2O7

Dichlorines heptaoxide (七氧化二氯)

Common names¡ H2O 水 Water¡ H2O2 雙氧水(過氧化氫) Hydrogen peroxide¡ NH3 氨 Ammonia¡ N2H4 肼 Hydrazine¡ C2H2 乙炔 Acetylene¡ PH3 磷化氫 Phosphine¡ AsH3 砷化氫 Arsine¡ NO 氧化氮 Nitric oxide¡ N2O 氧化亞氮 Nitrous oxide¡ CH4 甲烷 Methane

Acid¡ It containing H atoms ionize in water to form H+ ions

¡ Most acids contain oxygen in addition to hydrogen atoms as (oxoacids)ô H2CO3 碳酸 Carbonic acidô H2SO4 硫酸 Sulfuric acidô HNO3 硝酸 Nitric acidô HClO3 氯酸 Chloric acid

Hydroiodic acidH+,I－Hydrogen iodideHI

Hydrobormic acidH+,Br－Hydrogen bromideHBr

Hydrochloric acidH+,Cl－Hydrogen chlorideHCl

水溶液純物質

次氯酸

Hypochlorite ClO－次氯酸

Hypochlorous acidHClO

亞氯酸根

ChloriteClO2

－亞氯酸

Chlorous acidHClO2

氯酸根

ChlorateClO3

－氯酸

Chloric acidHClO3

過氯酸根

PerchlorateClO4

－過氯酸

Perchloric acidHClO4

含氧酸命名法則

次...酸hypo...ous acid

亞...酸...ous acid

酸ic

過...酸per...ic acid

含氧酸(oxoacid)

次...酸根hypo...ite

亞...酸根...ite

酸根ate

過...酸根per...ate

含氧酸陰離子oxoanion

Ex2.8: Give the names of

Sol:(a) HNO2亞硝酸 nitrous acid

(b) H2SO3亞硫酸 sulfurous acid

(c) HIO次碘酸 hypoiodous acid