Ch2 z53 particles
Transcript of Ch2 z53 particles
1
Chapter 2Chapter 2
Atoms, Molecules, and IonsAtoms, Molecules, and Ions pp
2
HistoryHistory GreeksGreeks Democritus and Leucippus - Democritus and Leucippus - atomosatomos Aristotle- elements.Aristotle- elements. AlchemyAlchemy 1660 - Robert Boyle- experimental 1660 - Robert Boyle- experimental
definition of element.definition of element. Lavoisier- Father of modern chemistry.Lavoisier- Father of modern chemistry. He wrote the book.He wrote the book.
3
LawsLaws Conservation of MassConservation of Mass Law of Definite Proportion - compounds Law of Definite Proportion - compounds
have a constant composition.have a constant composition. They react in specific ratios by mass.They react in specific ratios by mass. Multiple Proportions - When two elements Multiple Proportions - When two elements
form more than one compound, the ratios of form more than one compound, the ratios of the masses of the second element that the masses of the second element that combine with one gram of the first can be combine with one gram of the first can be reduced to small whole numbers.reduced to small whole numbers.
4
What?!What?! Water has 8 g of oxygen per g of hydrogen.Water has 8 g of oxygen per g of hydrogen. Hydrogen peroxide has 16 g of oxygen per Hydrogen peroxide has 16 g of oxygen per
g of hydrogen.g of hydrogen. 16/8 = 2/116/8 = 2/1 Small whole number ratios.Small whole number ratios.
5
ProofProof Mercury has two oxides. One is 96.2 % Mercury has two oxides. One is 96.2 %
mercury by mass, the other is 92.6 % mercury by mass, the other is 92.6 % mercury by mass.mercury by mass.
Show that these compounds follow the law Show that these compounds follow the law of multiple proportion.of multiple proportion.
Speculate on the formula of the two oxides.Speculate on the formula of the two oxides.
6
Dalton’s Atomic TheoryDalton’s Atomic Theory1)1) Elements are made up of atomsElements are made up of atoms
2)2) Atoms of Atoms of eacheach element are identical. element are identical. Atoms of Atoms of differentdifferent elements are different. elements are different.
3)3) CompoundsCompounds are formed when atoms are formed when atoms combine. Each compound has a specific combine. Each compound has a specific number and kinds of atom.number and kinds of atom.
4)4) Chemical reactions are rearrangement of Chemical reactions are rearrangement of atoms. Atoms are not created or atoms. Atoms are not created or destroyed.destroyed.
7
Gay-Lussac- under the same conditions of Gay-Lussac- under the same conditions of temperature and pressure, compounds temperature and pressure, compounds always react in whole number ratios by always react in whole number ratios by volume.volume.
Avagadro - interpreted that to mean . . . Avagadro - interpreted that to mean . . . at the same temperature and pressure, equal at the same temperature and pressure, equal
volumes of gas contain the same number of volumes of gas contain the same number of particles.particles.
(called (called Avagadro’s HypothesisAvagadro’s Hypothesis))
A Helpful ObservationA Helpful Observation
8
Figure 2.4Figure 2.4Representation of some of Gay-Lussac’s Experimental Representation of some of Gay-Lussac’s Experimental
Results on Combining Gas VolumesResults on Combining Gas Volumes
9
Figure 2.5 Figure 2.5 Representation of Combining Gases at the Representation of Combining Gases at the
Molecular LevelMolecular Level
10
Early Experiments to determine Early Experiments to determine what an atom waswhat an atom was
J. J. Thomson- used Cathode ray tubesJ. J. Thomson- used Cathode ray tubes
11
Thomson’s ExperimentThomson’s Experiment
Voltage source
+-
12
Thomson’s ExperimentThomson’s Experiment
Voltage source
+-
13
Passing an electric current makes a beam Passing an electric current makes a beam appear to move from the negative to the appear to move from the negative to the positive end.positive end.
Thomson’s ExperimentThomson’s Experiment
Voltage source
+-
14
Voltage source
Thomson’s ExperimentThomson’s Experiment
By adding an electric field By adding an electric field
15
Voltage source
Thomson’s ExperimentThomson’s Experiment
By adding an electric field, he found that By adding an electric field, he found that the moving pieces were negative the moving pieces were negative
+
-
16
Thomsom’s ModelThomsom’s Model Found the electron.Found the electron. Couldn’t find positive Couldn’t find positive
(for a while). (for a while). Said the atom was like Said the atom was like
plum pudding.plum pudding. A bunch of positive A bunch of positive
stuff, with the stuff, with the electrons able to be electrons able to be removed. removed.
17
Millikan’s ExperimentMillikan’s Experiment
Oil
Atomizer
Oil droplets
Telescope
-
+
18
Millikan’s ExperimentMillikan’s Experiment
X-rays
X-rays give some electrons a charge.
19
Millikan’s ExperimentMillikan’s Experiment
Some drops would hoverFrom the mass of the drop and the charge on the plates, he calculated the mass of an electron
20
Figure 2.10Figure 2.10Diagram of the Millikan Apparatus Diagram of the Millikan Apparatus
21
RadioactivityRadioactivity Discovered by accidentDiscovered by accident BequerelBequerel Three types Three types
– Alpha- helium nucleus (+2 charge, large Alpha- helium nucleus (+2 charge, large mass)mass)
– Beta - high speed electronBeta - high speed electron
– Gamma - high energy lightGamma - high energy light
22
Rutherford’s ExperimentRutherford’s Experiment Used uranium to produce alpha particles.Used uranium to produce alpha particles. Aimed alpha particles at gold foil by Aimed alpha particles at gold foil by
drilling hole in lead block.drilling hole in lead block. Since the mass is evenly distributed in Since the mass is evenly distributed in
gold atoms alpha particles should go gold atoms alpha particles should go straight through.straight through.
Used gold foil because it could be made Used gold foil because it could be made atoms thin.atoms thin.
23
Lead block
Uranium
Gold Foil
Florescent Screen
24
What he expected
25
Because
26
Because, he thought the mass was evenly distributed in the atom.
27
What he got
28
How he explained it
+
Atom is mostly emptyAtom is mostly empty Small dense,Small dense,
positive piecepositive pieceat center.at center.
Alpha particlesAlpha particlesare deflected byare deflected by it if it if they get closethey get close enough. enough.
29
+
30
Figure 2.12Figure 2.12Rutherford’s Experiment on Rutherford’s Experiment on particle particle
Bombardment of Metal FoilBombardment of Metal Foil
31
Figure 2.13Figure 2.13 Expected and Actual Results of Expected and Actual Results of
Rutherford’s ExperimentRutherford’s Experiment
32
Modern ViewModern View The atom is mostly The atom is mostly
empty space.empty space. Two regionsTwo regions Nucleus - protons Nucleus - protons
and neutrons.and neutrons. Electron cloud - Electron cloud -
region where you region where you mightmight find an find an electron.electron.
33
Sub-atomic ParticlesSub-atomic Particles Z - atomic number = number of protonsZ - atomic number = number of protons Z determines type of atom.Z determines type of atom. A - mass number = number of protons + A - mass number = number of protons +
neutrons.neutrons. Number of protons = number of electrons Number of protons = number of electrons if if
neutral.neutral.
34
The Mass and Change of the The Mass and Change of the Electron, Proton, and NeutronElectron, Proton, and NeutronThe Mass and Change of the The Mass and Change of the
Electron, Proton, and NeutronElectron, Proton, and Neutron
Particle Mass (kg) Charge
Electron 9.11 ¥ 10- 31 1-
Proton 1.67 ¥ 10- 27 1+
Neutron 1.67 ¥ 10- 27 0
35
SymbolsSymbols
XA
Z
Na23
11
36
Chemical BondsChemical Bonds The forces that hold atoms together.The forces that hold atoms together. Covalent bonding - sharing electrons.Covalent bonding - sharing electrons. Makes molecules.Makes molecules. Chemical formula - the number and type of Chemical formula - the number and type of
atoms in a molecule. atoms in a molecule. CC22HH66 - 2 carbon atoms, 6 hydrogen atoms, - 2 carbon atoms, 6 hydrogen atoms,
Structural formula shows the connections, Structural formula shows the connections, but not necessarily the shape.but not necessarily the shape.
37
H
H
H H
H
HC C
There are also other models that attempt to There are also other models that attempt to show three dimensional shape.show three dimensional shape.
Ball and stick or space-filling.Ball and stick or space-filling.
38
IonsIons Atoms or groups of atoms with a charge.Atoms or groups of atoms with a charge. Cations - positive ions - get by Cations - positive ions - get by losinglosing
electrons(s).electrons(s). Anions- negative ions - get by Anions- negative ions - get by gaininggaining
electron(s).electron(s). Ionic bonding - held together by the Ionic bonding - held together by the
opposite charges.opposite charges. Ionic Ionic solidssolids are called salts. are called salts.
39
Polyatomic IonsPolyatomic Ions Groups of atoms that have a charge.Groups of atoms that have a charge. Yes, you have to memorize them.Yes, you have to memorize them. See list on page 66See list on page 66
40
Periodic TablePeriodic Table
41
MetalsMetals ConductorsConductors Lose electronsLose electrons Malleable and ductileMalleable and ductile
42
NonmetalsNonmetals BrittleBrittle Gain electronsGain electrons Covalent bondsCovalent bonds
43
Semi-metals or MetalloidsSemi-metals or Metalloids
44
Alkali Metals
45
Alkaline Earth Metals
46
Halogens
47
Transition metals
48
Noble Gases
49
Inner Transition Metals
50
+1+2 -1-2-3
51
Naming compoundsNaming compounds Two typesTwo types IonicIonic - metal with non metal or with - metal with non metal or with
polyatomic ions.polyatomic ions. CovalentCovalent- we will just learn the rules for - we will just learn the rules for
non-metals combined with non-metal.non-metals combined with non-metal.
52
Ionic compoundsIonic compounds If the If the cationcation is monoatomic - Name the metal is monoatomic - Name the metal
(cation) just write the name.(cation) just write the name. Include a Roman numeral to indicate the oxidation Include a Roman numeral to indicate the oxidation
state if the cation (metal) has more than one.state if the cation (metal) has more than one. If the cation is polyatomic - name it.If the cation is polyatomic - name it. If the anion is monoatomic - name it but change If the anion is monoatomic - name it but change
the ending to the ending to –ide.–ide. If the anion is poly atomic - just name itIf the anion is poly atomic - just name it Practice.Practice.
53
Figure 2.22Figure 2.22 Common Cations and Anions Common Cations and Anions
57
Ionic CompoundsIonic Compounds Have to know what ions they formHave to know what ions they form Get from periodic table, polyatomic, or figure outGet from periodic table, polyatomic, or figure out CaSCaS
KK22SS
AlPOAlPO44
KK22SOSO44
FeSFeS CoICoI33
58
Figure 2.23Figure 2.23Flowchart Flowchart for Naming for Naming Binary Binary CompoundsCompounds
60
Ionic CompoundsIonic Compounds FeFe22(C(C22OO44))
MgOMgO MnOMnO
KMnOKMnO44
NHNH44NONO33
HgHg22ClCl22
CrCr22OO33
61
Ionic CompoundsIonic Compounds KClOKClO44
NaClONaClO33
YBrOYBrO22
Cr(ClO)Cr(ClO)66
62
Naming Covalent CompoundsNaming Covalent Compounds Two words, with prefixesTwo words, with prefixes Prefixes tell you how many.Prefixes tell you how many. mono, di, tri, tetra, penta, hexa, septa, nona, mono, di, tri, tetra, penta, hexa, septa, nona,
decadeca First element whole name with the First element whole name with the
appropriate prefix, except monoappropriate prefix, except mono Second element, Second element, -ide -ide ending with appropriate ending with appropriate
prefixprefix PracticePractice
63
COCO22
CO CO CClCCl44
NN22OO44
XeFXeF66
NN44OO44
PP22OO1010
Naming Covalent CompoundsNaming Covalent Compounds
64
Writing FormulasWriting Formulas Two sets of rules, ionic and covalentTwo sets of rules, ionic and covalent To decide which to use, decide what the To decide which to use, decide what the
first word is.first word is. If is a metal or polyatomic use ionic.If is a metal or polyatomic use ionic. If it is a non-metal use covalent.If it is a non-metal use covalent.
65
Ionic FormulasIonic Formulas Charges must add up to zero.Charges must add up to zero. Get charges from periodic table, name of Get charges from periodic table, name of
metal ion, or memorized from the list.metal ion, or memorized from the list. Use parentheses to indicate multiple Use parentheses to indicate multiple
polyatomics.polyatomics.
66
Ionic FormulasIonic Formulas Sodium nitrideSodium nitride Sodium - Na is always +1Sodium - Na is always +1 nitride - ide tells you it comes from the nitride - ide tells you it comes from the
periodic tableperiodic table nitride is Nnitride is N-3-3
67
Ionic FormulasIonic Formulas Sodium nitrideSodium nitride Sodium - Na is always +1Sodium - Na is always +1 Nitride - ide tells you it comes from the Nitride - ide tells you it comes from the
tabletable nitride is Nnitride is N-3-3 Doesn’t add up to zero (if 1:1 ratio).Doesn’t add up to zero (if 1:1 ratio).
Na+1 N-3
68
Ionic FormulasIonic Formulas Sodium nitrideSodium nitride sodium- Na is always +1sodium- Na is always +1 nitride - ide tells you it comes from the tablenitride - ide tells you it comes from the table nitride is Nnitride is N-3-3 Doesn’t add up to zeroDoesn’t add up to zero So, need 3 Na (“Cross the charges”)So, need 3 Na (“Cross the charges”)
Na+1 N-3 Na3N
69
Ionic CompoundsIonic Compounds Sodium sulfiteSodium sulfite calcium iodidecalcium iodide Lead (II) oxide Lead (II) oxide Lead (IV) oxideLead (IV) oxide Mercury (I) sulfideMercury (I) sulfide Barium chromateBarium chromate Aluminum hydrogen sulfateAluminum hydrogen sulfate Cerium (IV) nitriteCerium (IV) nitrite
70
Covalent compoundsCovalent compounds The name tells you how to write the The name tells you how to write the
formulaformula duhduh Sulfur dioxideSulfur dioxide difluorine monoxidedifluorine monoxide nitrogen trichloridenitrogen trichloride diphosphorus pentoxidediphosphorus pentoxide
71
Chemical Naming pp:
P = cation
Q = anion
73
AcidsAcids Substances that produce HSubstances that produce H++ ions when ions when
dissolved in water.dissolved in water. All acids begin with H.All acids begin with H. Two types of Two types of inorganicinorganic acids: acids: OxyacidsOxyacids Non-oxyacidsNon-oxyacids OrganicOrganic acids have -COOH group acids have -COOH group
74
Naming acidsNaming acids If the formula has oxygen in itIf the formula has oxygen in it write the name of the anion, but change write the name of the anion, but change
– ate to -ic acidate to -ic acid– ite to -ous acidite to -ous acid
Hint: “m -ic- e” or more than a “m -ous- e”Hint: “m -ic- e” or more than a “m -ous- e” Watch out for sulfWatch out for sulfururic and sulfic and sulfururousous
HH22CrOCrO44
HMnOHMnO44
HNOHNO22
75
Naming acidsNaming acids If the acid doesn’t have oxygenIf the acid doesn’t have oxygen add the prefix hydro-add the prefix hydro- change the suffix -ide to -ic acidchange the suffix -ide to -ic acid HClHCl HH22SS
HCNHCN
76
Formulas for acidsFormulas for acids Working backwards from names.Working backwards from names. If it has hydro- in the name it has no oxygenIf it has hydro- in the name it has no oxygen Anion ends in -ideAnion ends in -ide No hydro, anion ends in -ate or -ite (and it No hydro, anion ends in -ate or -ite (and it
is an oxyacid)is an oxyacid) Write anion and add enough H to balance Write anion and add enough H to balance
the charges.the charges.
77
Figure 2.25 Flowchart for Naming Acids Figure 2.25 Flowchart for Naming Acids pp
78
Formulas for acidsFormulas for acids hydrofluoric acidhydrofluoric acid dichromic aciddichromic acid carbonic acidcarbonic acid hydrophosphoric acidhydrophosphoric acid hypofluorous acidhypofluorous acid perchloric acidperchloric acid phosphorous acid phosphorous acid
79
HydratesHydrates Some salts trap water crystals when they Some salts trap water crystals when they
form crystals.form crystals. These are hydrates.These are hydrates. Both the name and the formula need to Both the name and the formula need to
indicate how many water molecules are indicate how many water molecules are trapped.trapped.
In the name we add the word hydrate with a In the name we add the word hydrate with a prefix that tells us how many water prefix that tells us how many water molecules. molecules.
80
HydratesHydrates pp
In the formula you put a dot and then write In the formula you put a dot and then write the number of molecules.the number of molecules.
Calcium chloride dihydrate = CaClCalcium chloride dihydrate = CaCl222222 Chromium (III) nitrate hexahydrate = Chromium (III) nitrate hexahydrate =
Cr(NOCr(NO33))33 6H 6H22O O