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