Atoms, Molecules, and Ions Dalton’s Atomic Theory 1) Elements are made up of atoms 2) Atoms of each element are identical. Atoms of different elements.
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AtomsAtoms, , MoleculesMolecules, and , and Ions Ions
Dalton’s Atomic TheoryDalton’s Atomic Theory
1)1) Elements are made up of atomsElements are made up of atoms
2)2) Atoms of each element are identical. Atoms of each element are identical. Atoms of different elements are Atoms of different elements are different.different.
3)3) Compounds are formed when atoms Compounds 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 Chemical reactions are rearrangement of atoms. Atoms are not created or of atoms. Atoms are not created or destroyed.destroyed.
LawsLaws
Conservation of MassConservation of Mass Law of Definite Proportion-Law of Definite Proportion- compounds compounds
have a constant composition.have a constant composition. They react in specific ratios by mass.They react in specific ratios by mass. Law of Multiple Proportions-Law of Multiple Proportions- When two When two
elements form more than one compound, elements form more than one compound, the ratios of the masses of the second the ratios of the masses of the second element that combine with one gram of element that combine with one gram of the first can be reduced to the first can be reduced to small whole small whole numbers.numbers.
What?!What?!
Water has 8 g of oxygen per g of Water has 8 g of oxygen per g of hydrogen.hydrogen.
Hydrogen peroxide has 16 g of Hydrogen peroxide has 16 g of oxygen per g of hydrogen.oxygen per g of hydrogen.
16/8 = 2/116/8 = 2/1 Small whole number ratios.Small whole number ratios.
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 Show that these compounds follow the law of multiple proportion.the law of multiple proportion.
Speculate on the formula of the two Speculate on the formula of the two oxides.oxides.
Gay-LussacGay-Lussac- under the same - under the same conditions of temperature and conditions of temperature and pressure, compounds always react in pressure, compounds always react in whole number ratios by volume.whole number ratios by volume.
AvagadroAvagadro- interpreted that to mean - interpreted that to mean at the same temperature and at the same temperature and pressure, equal volumes of gas pressure, equal volumes of gas contain the same number of contain the same number of particles.particles.
(called (called Avagadro’s HypothesisAvagadro’s Hypothesis))
A Helpful ObservationA Helpful Observation
Experiments to determine Experiments to determine what an atom waswhat an atom was
J. J. Thomson-J. J. Thomson- used Cathode ray used Cathode ray tubestubes
Thomson’s ExperimentThomson’s Experiment
Voltage source
+-
Thomson’s ExperimentThomson’s Experiment
Voltage source
+-
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
+-
Voltage source
Thomson’s ExperimentThomson’s Experiment
By adding an electric field By adding an electric field
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
+
-
Thomsom’s ModelThomsom’s Model
Found the electron.Found the electron. Couldn’t find Couldn’t find
positive (for a positive (for a while). while).
Said the atom was Said the atom was like like plum puddingplum 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.
Millikan’s ExperimentMillikan’s Experiment
Oil
Atomizer
Oil droplets
Telescope
-
+
Millikan’s ExperimentMillikan’s Experiment
X-rays
X-rays give some electrons a charge.
Millikan’s ExperimentMillikan’s Experiment
Some drops would hover
From the mass of the drop and the charge on the plates, he calculated the mass of an electron
Rutherford’s ExperimentRutherford’s Experiment
Used uranium to produce Used uranium to produce alpha alpha particlesparticles..
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 Used gold foil because it could be made atoms thin.made atoms thin.
Lead block
Uranium
Gold Foil
Florescent Screen
What he expected
Because
Because, he thought the mass was evenly distributed in the atom.
What he got
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 they get closeit if they get close enough.enough.
+
Modern ViewModern View
The atom is The atom is mostly empty mostly empty space.space.
Two regionsTwo regions Nucleus- protons Nucleus- protons
and neutrons.and neutrons. Electron cloud- Electron cloud-
region where you region where you might find an might find an electron.electron.
Sub-atomic ParticlesSub-atomic Particles
Z - atomic number = number of Z - atomic number = number of protons determines type of atom.protons determines type of atom.
A - mass number = number of A - mass number = number of protons + neutrons.protons + neutrons.
Number of protons = number of Number of protons = number of electrons if neutral.electrons if neutral.
SymbolsSymbols
XA
Z
Na23
11
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 Chemical formula- the number and type
of atoms in a molecule. of atoms in a molecule. CC22HH66 - 2 carbon atoms, 6 hydrogen - 2 carbon atoms, 6 hydrogen
atoms, atoms, Structural formula shows the connections, Structural formula shows the connections,
but not necessarily the shape.but not necessarily the shape.
H
H
H H
H
HC C
There are also other model that There are also other model that attempt to show three dimensional attempt to show three dimensional shape.shape.
Ball and stick.Ball and stick.
IonsIons
Atoms or groups of atoms with a Atoms or groups of atoms with a charge.charge.
Cations- positive ions - get by losing Cations- positive ions - get by losing electrons(s).electrons(s).
Anions- negative ions - get by gaining Anions- negative ions - get by gaining electron(s).electron(s).
Monatomic ions – chart pg. 73Monatomic ions – chart pg. 73 Ions of transition metals – chart pg. 75Ions of transition metals – chart pg. 75 Monatomic negative ions – chart pg. 81Monatomic negative ions – chart pg. 81
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. A charged group of covalently A charged group of covalently
bonded atoms that generally act as a bonded atoms that generally act as a group.group.
Polyatomic ion chart – pg. 76.Polyatomic ion chart – pg. 76.
Periodic TablePeriodic Table
ClassificationClassification
BlocksBlocks GroupsGroups PeriodsPeriods
MetalsMetals ConductorsConductors Lose electronsLose electrons Malleable and ductileMalleable and ductile
NonmetalsNonmetals
BrittleBrittle Gain electronsGain electrons Covalent bondsCovalent bonds
Non-metals are generally Non-metals are generally called oxidizers – because called oxidizers – because they accept electrons readilythey accept electrons readily
Metals are referred to as Metals are referred to as reducers because they give reducers because they give up electrons readilyup electrons readily
Semi-metals or MetalloidsSemi-metals or Metalloids
Alkali Metals
Alkaline Earth Metals
Halogens
Transition metals
Noble Gases
Inner Transition Metals
+1+2 -1-2-3
Naming compoundsNaming compounds
Two typesTwo types IonicIonic - metal and non metal or - metal and non metal or
polyatomics.polyatomics. CovalentCovalent- we will just learn the rules - we will just learn the rules
for 2 non-metals.for 2 non-metals.
Ionic compoundsIonic compounds
If the cation is monoatomic- Name the If the cation is monoatomic- Name the metal (cation) just write the name.metal (cation) just write the name.
If the cation is polyatomic- name itIf the cation is polyatomic- name it If the anion is monoatomic- name it If the anion is monoatomic- name it
but change the ending to but change the ending to -ide-ide If the anion is poly atomic- just name If the anion is poly atomic- just name
itit practicepractice
Ionic CompoundsIonic Compounds
Have to know what ions they formHave to know what ions they form off table, polyatomic, or figure it outoff table, polyatomic, or figure it out CaSCaS KK22SS
AlPOAlPO44 KK22SOSO44
FeSFeS CoICoI33
Ionic CompoundsIonic Compounds
FeFe22(C(C22OO44))
MgOMgO MnOMnO
KMnOKMnO44
NHNH44NONO33
HgHg22ClCl22
CrCr22OO33
Ionic CompoundsIonic Compounds
KClOKClO44
NaClONaClO33
YBrOYBrO22
Cr(ClO)Cr(ClO)66
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, mono, di, tri, tetra, penta, hexa, septa,
nona, decanona, deca 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 ending with
appropriate prefixappropriate prefix PracticePractice
COCO22
CO CO CClCCl44
NN22OO44
XeFXeF66
NN44OO44
PP22OO1010
Naming Covalent CompoundsNaming Covalent Compounds
Writing FormulasWriting Formulas
Two sets of rules, ionic and covalentTwo sets of rules, ionic and covalent To decide which to use, decide what To decide which to use, decide what
the first word is.the 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.
Ionic FormulasIonic Formulas
Charges must add up to zero.Charges must add up to zero. Get charges from table, name of Get charges from table, name of
metal ion, or memorized from the metal ion, or memorized from the list.list.
Use parenthesis to indicate multiple Use parenthesis to indicate multiple polyatomics.polyatomics.
Ionic FormulasIonic Formulas
Sodium nitrideSodium nitride sodium- Na is always +1sodium- Na is always +1 nitride - ide tells you it comes from nitride - ide tells you it comes from
the tablethe table nitride is Nnitride is N-3-3
Ionic FormulasIonic Formulas
Sodium nitrideSodium nitride sodium- Na is always +1sodium- Na is always +1 Nitride - ide tells you it comes from Nitride - ide tells you it comes from
the tablethe table nitride is Nnitride is N-3-3 Doesn’t add up to zero.Doesn’t add up to zero.
Na+1 N-3
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 zeroDoesn’t add up to zero Need 3 NaNeed 3 NaNa+1 N-3 Na3N
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
Covalent compoundsCovalent compounds
The name tells you how to write the The name tells you how to write the formulaformula
duhduh Sulfur dioxideSulfur dioxide diflourine monoxidediflourine monoxide nitrogen trichloridenitrogen trichloride diphosphorus pentoxidediphosphorus pentoxide
More Names and More Names and formulasformulas
AcidsAcids
Substances that produce HSubstances that produce H++ ions ions when dissolved in water.when dissolved in water.
All acids begin with H.All acids begin with H. Two types of acids: Two types of acids: OxyacidsOxyacids Non-oxyacidsNon-oxyacids
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
Watch out for sulfWatch out for sulfururic and sulfic and sulfururousous HH22CrOCrO44
HMnOHMnO44
HNOHNO22
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
Formulas for acidsFormulas for acids
Backwards from names.Backwards from names. If it has hydro- in the name it has no If it has hydro- in the name it has no
oxygenoxygen Anion ends in -ideAnion ends in -ide No hydro, anion ends in -ate or -iteNo hydro, anion ends in -ate or -ite Write anion and add enough H to Write anion and add enough H to
balance the charges.balance the charges.
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
HydratesHydrates
Some salts trap water crystals when Some salts trap water crystals when they form crystals.they form crystals.
These are hydrates.These are hydrates. Both the name and the formula Both the name and the formula
needs to indicate how many water needs to indicate how many water molecules are trapped.molecules are trapped.
In the name we add the word In the name we add the word hydrate with a prefix that tells us hydrate with a prefix that tells us how many water molecules. how many water molecules.
HydratesHydrates
In the formula you put a dot and then In the formula you put a dot and then write the number of molecules.write the number of molecules.
Calcium chloride dihydrate = Calcium chloride dihydrate = CaClCaCl2222
Chromium (III) nitrate hexahydrate = Chromium (III) nitrate hexahydrate = Cr(NOCr(NO33))33 6H 6H22O O
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