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Copyright © by Houghton Mifflin Company. All rights reserved.
What is atom?
Electron
Nucleus
Atomic Structure
Copyright © Cengage Learning. All rights reserved 3
Greeks were the first to attempt to explain why chemical changes occur.
Alchemy dominated for 2000 years. Several elements discovered. Mineral acids prepared.
Robert Boyle was the first “chemist”. Performed quantitative experiments. Developed first experimental definition of an
element.
Early History of Chemistry
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The Discovery of Electrons
J.J. Thomson –CRT experiment
Robert Millikan – Oil droplets experiment
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Early Experiments to Characterize the atom
Measurement of electron
J.J. Thomson (1856-1940)
Cathode-ray tube experiment (1898-1903)
e/m = -1.76× 108 C/g
J. J. Thomson (1898—1903) Postulated the existence of negatively charged
particles, that we now call electrons, using cathode-ray tubes.
Determined the charge-to-mass ratio of an electron.
The atom must also contain positive particles that balance exactly the negative charge carried by electrons.
Copyright © Cengage Learning. All rights reserved 6
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Early Experiments to Characterize the atom
Measurement of electron weight
Robert Millikan (1868-1953)
Nobel Prize in Physics in 1923
Oil droplets experiment (1909) m = 9.11X 10-31 Kg
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Early Experiments to Characterize the atom
Ernest Rutherford (1871-1937)
Nobel Prize in Chemistry in 1908
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The Results from Rutherford The majority of a particles penetrated the foil
undeflected.(穿透 ) Some particles experienced slight deflections.
(小角度偏折 ) A few (about one in every 20000) suffered rather
serious deflections as they penetrated the foil.
(嚴重偏折 ) A similar number did not pass through the foil at
all but “bounced back” in the direction from which they had come.(反彈 )
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The Model of Rutherford Most of the mass and all of the positive charge of an
atom are centered in a very small region called the nucleus. (原子重量集中於一個小區域 )
The atom is mostly empty space. The magnitude of the positive charge is different for
different atoms and is approximately one half the atomic weight of the element.(正電荷重量為原子的1/2)
There exist as many electrons outside the nucleus as there are units of positive charge on the nucleus. The atom as a whole is electrically neutral.(原子為電中性 )
Henri Becquerel (1896)
Discovered radioactivity by observing the spontaneous emission of radiation by uranium.
Nobel Prize in Physics in 1903 Three types of radioactive emission exist:
Gamma rays (ϒ) – high energy light Beta particles (β) – a high speed electron Alpha particles (α) – a particle with a 2+ charge
Copyright © Cengage Learning. All rights reserved 16
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Founder of Radioactivity
Marie Sklodowska Curie ( Poland 1867-1934)
Found new element polonium (Po 釙 ) in 1898
Nobel Prize in Physics in 1903
Found new element radium (Ra 鐳 ) in 1898
Nobel Prize in chemistry in 1911
Isotopes are identified by: Atomic Number (Z) – number of protons Mass Number (A) – number of protons plus
number of neutrons
Copyright © Cengage Learning. All rights reserved 21
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Components of Atoms in Physics
電量 電子家族 緲子家族 陶子家族
夸克(quark
)
+2/3上夸克 u (up quark)
m ~ 0.01GeV
魅夸克 c (charm quark)m ~ 1.5GeV
頂夸克 t (top quark)
m > 89GeV
-1/3下夸克 d
(down quark)m ~ 0.01GeV
奇夸克 s (strange quark)m ~ 0.15GeV
底夸克 b (bottom quark)m ~ 5.5GeV
輕子(lepton
)
0電子微中子 v
(electron neutrino)m < 2×10-8GeV
緲子微中子v(muon neutrino)
m < 2×10 -
4GeV
陶子微中子 v(tau
neutrino)m < 0.035GeV
-1電子 e (electron)
m = 5.11×10-4
GeV
緲子 ν(muon)m = 0.106GeV
陶子 τ(tau)m = 1.75GeV
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Naming Simple Compounds
Binary Compounds (Type I; Ionic)
Binary Compounds (Type II; Ionic)
Binary Compounds (Type III; Contain Two Nonmetals)
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Binary Compounds (Type I; Ionic)
Rules1. The cation is always named first and anion
second.
2. A monatomic cation takes its name from the name of element.
3. A monatomic anion is named by taking the first part of the element name and adding –ide.
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Naming Compounds For Type I
1. NaCl
2. NaH
3. KI
4. MgO
5. BN
Binary Ionic Compounds (Type II) Metals in these compounds form more than one type of
positive ion. Charge on the metal ion must be specified. Roman numeral indicates the charge of the metal
cation. Transition metal cations usually require a Roman
numeral. Elements that form only one cation do not need to be
identified by a roman numeral.
Copyright © Cengage Learning. All rights reserved 27
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Ion Systematic Name
Fe+3 Iron(III)
Fe+2 Iron(II)
Cu+2 Copper(II)
Cu+ Copper(I)
Co+3 Cobalt(III)
Co+2 Cobalt(II)
Sn+4 Tin(IV)
Sn+2 Tin(II)
Pb+4 Lead(IV)
Pb+2 Lead(II)
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Binary Compounds (Type II; Ionic)
Rules for Polyatomic Ions
1. Contain polyatomic ions. ex. NH+4, CN-, SO4
-2
2. Polyatomic ions are assigned special names that must be memorized to name the compounds.3. For oxyanions, the name of the one with the smaller number of oxygen atoms ends in –ite, and the name of the one with the larger number of oxygen atoms ends in –ate4. When more than two oxyanions make up a series, hypo- (less than) for fewest oxygen atoms and per- (more than) for the most oxygen atoms are used.
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Binary Compounds (Type II; Ionic)
CoBr2
CaCl2Al2O3
CrCl3
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Binary Compounds (Type III; Contain Two Nonmetals)
Rules
1. The first element in the formula is named first,
using the full element name.
2. The second element is named as if it was an
anion.
3. Prefixes are used to denote the numbers of
atoms.
4. The prefix mono- is never used for naming the
first element.
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Prefix Number Indicated
Mono- 1
Di- 2
Tri- 3
Tetra- 4
Penta 5
Hexa- 6
Hepta- 7
Octa- 8
Nona- 9
Deca- 10
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Problems for naming
CuI NaClO4
SF2
Mg(OH)2
Ag2CrO4
Li3N
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Question
Which is not the correct chemical formula for the compound named? potassium phosphate, K3PO4 iron(II) oxide, FeO calcium carbonate, CaCO3 sodium sulfide, NaS lithium nitrate, LiNO3
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Answer
d) sodium sulfide, NaS
Sodium sulfide is a binary compound composed of a Group 1 element, whose charge in compounds is +1, and a Group 16 element, whose charge in binary compounds is commonly –2. This means that two sodium ions must be combined with one sulfide ion to form a neutral compound.
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Question
Which of the following is not the correct chemical formula for the compound named? Li2O, lithium oxide
FePO4, iron(III) phosphate HF, hydrogen fluoride BaCl2, barium dichloride
Mg3N2, magnesium nitride
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Answer
d) BaCl2, barium dichloride
The binary compound, BaCl2, is composed of a metal and a nonmetal. Its correct name is barium chloride (no prefix is needed).
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Question
Which is the correct formula for copper(I) sulfide? CuS Cu2S
CuS2
Cu2S2
None of the above
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Answer
b) Cu2S
The copper(I) ion has a +1 charge and the sulfide ion has a –2 charge.
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Question
What is the correct name for this compound with the formula Mg3(PO4)2? Trimagnesium diphosphate Magnesium(II) phosphate Magnesium phosphate Magnesium(II) diphosphate Magnesium(III) diphosphate