1 chapter 3 structure of the atom chapter 3 notes

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Chapter 3Chapter 3Structure of the AtomStructure of the Atom

Chapter 3 NotesChapter 3 Notes

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BrainteaserBrainteaser

What makes one What makes one element different from element different from another?another?

In the beginning….there were only In the beginning….there were only the elements which were divided the elements which were divided based on their properties.based on their properties.

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Chemical SymbolsChemical Symbols

A letter or letter pair that A letter or letter pair that represents the name of an represents the name of an element, similar to an element, similar to an abbreviation.abbreviation.

C = Carbon C = Carbon Ag = Argentum (latin) = SilverAg = Argentum (latin) = Silver

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Types of Sub-Atomic ParticlesTypes of Sub-Atomic Particles

TypeType SymbolSymbol (amu) (amu) LocationLocationProton Proton (+) (+) 1 1 nucleusnucleusNeutron Neutron (n) (n) 1 1 nucleusnucleusElectronElectron (-) (-) 0 0 around thearound the

nucleusnucleus

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Types of Sub-Atomic ParticlesTypes of Sub-Atomic Particles

Type Symbol Type Symbol R. Mass R. Mass LocationLocation Proton Proton (+) (+) 1836 1836 nucleusnucleus Neutron (n) Neutron (n) 1839 1839 nucleusnucleus Electron (-) Electron (-) 1 1 around thearound the

NucleusNucleus

Differences in atoms arise from Differences in atoms arise from differences in the amounts of differences in the amounts of each particle in the atom. each particle in the atom.

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About The AtomAbout The Atom

Mass NumberMass Number – the number of – the number of protons + number of neutrons, very protons + number of neutrons, very similar to the atomic mass.similar to the atomic mass.

Atomic NumberAtomic Number – The number of – The number of protons in the nucleus of an atom.protons in the nucleus of an atom.

Number of NeutronsNumber of Neutrons = mass number = mass number – atomic number– atomic number

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Practice ProblemsPractice ProblemsHow Many How Many

Protons/Neutrons/Electrons are Protons/Neutrons/Electrons are present in:present in:

LithiumLithiumSodiumSodiumBerylliumBerylliumGoldGold

What is the atomic number for:What is the atomic number for:CarbonCarbonHeliumHeliumIronIronCopperCopper

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Changing the AtomChanging the Atom

1.1. Change the number of Change the number of ProtonsProtons New New AtomAtom, new properties, new properties

2.2. Change the number of Change the number of NeutronsNeutrons New New IsotopeIsotope (could be radioactive) (could be radioactive)

3.3. Change the number of Change the number of ElectronsElectrons New New IonIon (holds a charge) (holds a charge)

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Changing the Number of Changing the Number of ProtonsProtons

New Element, New PropertiesNew Element, New Properties

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The Periodic TableThe Periodic Table

Brainteaser:Brainteaser: How would you How would you orderly arrange the pencils and orderly arrange the pencils and pens of each member of our pens of each member of our class? class?

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1800 – Dimitri Mendeleev (Russian)1800 – Dimitri Mendeleev (Russian)Organized the periodic table of the Organized the periodic table of the

elementselementsPeriodicPeriodic – repeated in a pattern – repeated in a patternChemical properties of the lighter Chemical properties of the lighter

elements repeated in the heavier elementselements repeated in the heavier elementsLeft empty spaces based on the properties Left empty spaces based on the properties

of elements not yet discovered (Ge)of elements not yet discovered (Ge)Organized left to right based on Organized left to right based on massmass

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Dimitri’s Periodic

Table

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Modern ModificationsModern Modifications

19131913 - Mosley reorganized left - Mosley reorganized left to right based on atomic to right based on atomic number number

always increasesalways increases

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GroupsGroupsGroupsGroups – Vertical columns – Vertical columnsSimilar propertiesSimilar propertiesSame number of electrons in Same number of electrons in

their outer shelltheir outer shell

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PeriodsPeriodsPeriodsPeriods – Horizontal rows – Horizontal rowsL to R increase in atomic numberL to R increase in atomic numberUp to down increase in electron Up to down increase in electron

shell energy levelshell energy level

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MetalsMetals – good conductors, solids – good conductors, solids at room temperature, shiny.at room temperature, shiny.

NonmetalsNonmetals – mostly gases, – mostly gases, brittle, bad conductorsbrittle, bad conductors

MetalloidsMetalloids – have properties of – have properties of both metals and non-metalsboth metals and non-metals

Hg – BrHg – Br only liquids on the only liquids on the periodic tableperiodic table

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The FamiliesThe FamiliesAlkali Metals – Group 1Alkali Metals – Group 1Alkaline Earth Metals – Group 2Alkaline Earth Metals – Group 2Chalcogens – Group 16Chalcogens – Group 16Halogens – Group 17Halogens – Group 17Nobel Gases – Group 18Nobel Gases – Group 18Transition Metals – Groups 3-12Transition Metals – Groups 3-12Lanthanides – Top Row BottomLanthanides – Top Row BottomActinides – Bottom Row BottomActinides – Bottom Row Bottom

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Periodic PropertiesPeriodic Properties

More reactive at the edges of the tableMore reactive at the edges of the tableNoble gasses do not reactNoble gasses do not react

Periodic Trends: Periodic Trends: increases if…increases if…ElectronegativityElectronegativity – electron greedy (Up – electron greedy (Up

and Right)and Right)SizeSize – (Down and Left) – (Down and Left) Ionization EnergyIonization Energy – electron give away – electron give away

(down and left)(down and left)

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Diatomic MoleculesDiatomic Molecules – molecules – molecules made of two atomsmade of two atomsNaturally occurring on the Naturally occurring on the

periodic tableperiodic tableBr-I-N-Cl-H-O-FBr-I-N-Cl-H-O-F

AllotropesAllotropes – Different forms of the – Different forms of the same elementsame element

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AllotropesAllotropes

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Changing the Number of Changing the Number of NeutronsNeutrons

Isotopes…RadioactivityIsotopes…Radioactivity

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IsotopesIsotopes

IsotopesIsotopes – atoms of the same – atoms of the same element that have a different number element that have a different number of neutrons.of neutrons.

QuestionQuestion:: Iodine is found in one of Iodine is found in one of two isotopes, I-131 and I-130. How two isotopes, I-131 and I-130. How many Neutrons are present in each?many Neutrons are present in each?

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Average Atomic MassAverage Atomic Mass

Average atomic mass – Average atomic mass – the the average mass of the mixture of its average mass of the mixture of its isotopes (different from the actual isotopes (different from the actual atomic mass)atomic mass)

QuestionQuestion:: If we have 5 atoms, 4 with If we have 5 atoms, 4 with the atomic mass of 11 and one with the atomic mass of 11 and one with the atomic mass of 10, what is the the atomic mass of 10, what is the average atomic mass?average atomic mass?

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Practice ProblemsPractice Problems

Question:Question: a chlorine atom has 17 a chlorine atom has 17 protons and 18 neutrons. What is the protons and 18 neutrons. What is the mass number? What is the atomic mass number? What is the atomic number?number?

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RadioactivityRadioactivity

Some Isotopes are radioactive, they are Some Isotopes are radioactive, they are too heavy (filled with neutrons) to be too heavy (filled with neutrons) to be stablestable

They give off radiation to “transmutate” They give off radiation to “transmutate” and become a lighter, more stable elementand become a lighter, more stable element

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Types of RadiationTypes of Radiation AlphaAlpha – two neutrons and two protons given – two neutrons and two protons given

off (one electron shy of being helium) off (one electron shy of being helium)

BetaBeta – losing a positive charge, a proton – losing a positive charge, a proton converts to a neutron.converts to a neutron.

GammaGamma – no mass, but high energy given – no mass, but high energy given off by the nucleusoff by the nucleus

Types of RadiationTypes of Radiation

RnHeRa 21886

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ePaTh 01

23491

23490

0023490

42

23892 2 ThHeU

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Calculating Half LifeCalculating Half Life

The amount of radioactive isotope remaining can The amount of radioactive isotope remaining can be calculated:be calculated:

NNtt = N = Noo x (0.5) x (0.5) (number of half-lives)(number of half-lives)

NNtt = amount of radioisotope remaining = amount of radioisotope remaining

NNoo = original amount of radioisotope = original amount of radioisotope

number of half-lives = time ÷ half-life number of half-lives = time ÷ half-life

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Uses of RadiationUses of Radiation Half Life – Radio Carbon Dating (Half Life – Radio Carbon Dating (ArchiologyArchiology))

Radioactive Tracers (Medicine)Radioactive Tracers (Medicine)

Effects of Radiation on the BodyEffects of Radiation on the Body

Fission vs. FusionFission vs. Fusion

Atomic WeaponsAtomic Weapons (Fission and Fusion) (Fission and Fusion)

Using Radiation for Energy (Nuclear Power)Using Radiation for Energy (Nuclear Power) (Fission) (Fission)

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Changing the Number of Changing the Number of ElectronsElectrons

IONSIONS

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Drawing Planetary ModelsDrawing Planetary Models

1.1. Find Atomic Number = Number of Find Atomic Number = Number of ElectronsElectrons

2.2. Circle for nucleus including Circle for nucleus including number of protons and neutrons number of protons and neutrons (+ =, n =)(+ =, n =)

3.3. Draw orbits with correct number of Draw orbits with correct number of electrons in each, filling in to outelectrons in each, filling in to out

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Drawing Planetary ModelsDrawing Planetary Models

Energy LevelEnergy Level Number of Number of ElectronsElectrons

11 22

22 88

33 1818

44 3232

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Draw Planetary Models for the Draw Planetary Models for the Following:Following:

LithiumLithiumCarbonCarbonIronIron

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Lewis Dot StructuresLewis Dot Structures

A diagram of an atoms showing A diagram of an atoms showing the valence electronsthe valence electrons

Valence electronsValence electrons – outer – outer electronselectronsWhere all exciting chemistry Where all exciting chemistry

happenshappens

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How to Draw Lewis Dot StructuresHow to Draw Lewis Dot Structures

1.1. Period = Energy levelPeriod = Energy level

2.2. Skipping the transition metals Skipping the transition metals and counting group 1 as 1, count and counting group 1 as 1, count right to the position of your right to the position of your element.element.

3.3. The number = the electrons in The number = the electrons in the outer shellthe outer shell

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How to Draw Lewis Dot StructuresHow to Draw Lewis Dot Structures

4.4. Draw the element symbolDraw the element symbol5.5. Draw one dot on each of the Draw one dot on each of the

4 sides, then double up when 4 sides, then double up when necessary (max 8 dots)necessary (max 8 dots)

Octet RuleOctet Rule – Atoms considered – Atoms considered to be stable have 8 electrons in to be stable have 8 electrons in their outermost shelltheir outermost shell

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Practice ProblemsPractice ProblemsGive the periodic group number and Give the periodic group number and

number of valence electrons for number of valence electrons for each of the following atoms:each of the following atoms:

CC ClCl NeNe SiSi SeSe AlAl

Write Lewis Dot Structures for:Write Lewis Dot Structures for: KK MgMg SS ArAr

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IonsIons

All atoms are naturally neutral All atoms are naturally neutral (0 charge)(0 charge)

Electrons can be gained and Electrons can be gained and lost to create a net + or – lost to create a net + or – chargecharge

Na Na → Na→ Na++ + e + e- - (Ionic Equation)(Ionic Equation)

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IonsIons

CationsCations – positive ion – formed when – positive ion – formed when one or more electrons are one or more electrons are lostlost from from an atoman atomNa Na → Na→ Na++ + e + e--

AnionAnion – negative ion – formed when – negative ion – formed when one or more electrons are one or more electrons are gainedgainedCl Cl + e+ e- - → → CCll--

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IonsIonsIons are formed in repeated Ions are formed in repeated

predictable patterns found on the predictable patterns found on the periodic tableperiodic table

Gaining or losing electrons to reveal Gaining or losing electrons to reveal an octet – atom’s goalan octet – atom’s goal

Alkalli metals – all (+1)Alkalli metals – all (+1)Halogens – all (-1)Halogens – all (-1)Transition metals – form (+) ionsTransition metals – form (+) ions

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Periodic IonsPeriodic Ions

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Ionic CompoundsIonic Compounds

Ions separate in solutionIons separate in solutionHigh melting pointsHigh melting pointsMostly between metals and Mostly between metals and

nonmetalsnonmetalsCharged ions in solution carry current Charged ions in solution carry current

through solution or when melted – through solution or when melted – conduct electricityconduct electricitySaltwater vs. WaterSaltwater vs. Water

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Ionic CompoundsIonic CompoundsMust have one cation and one Must have one cation and one

anion (metal and non-metal)anion (metal and non-metal)Total charge must equal Total charge must equal zerozeroMultiply either the positive or Multiply either the positive or

negative ion by a factor until sum negative ion by a factor until sum is zerois zero

Chemical BondChemical Bond – a force that – a force that holds together the atoms in a holds together the atoms in a substancesubstance

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Writing Molecular FormulasWriting Molecular Formulas

Listing of the types of atoms Listing of the types of atoms (chemical symbols) and numbers (chemical symbols) and numbers (subscripts) of each in a molecule(subscripts) of each in a moleculeNN22OO55

SOSO33

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Why atoms bondWhy atoms bond

Atoms wish to be chemically Atoms wish to be chemically stablestable

Octet RuleOctet Rule – an element is stable – an element is stable when it has 8 outer electronswhen it has 8 outer electrons

An atom will seek to have 8 outer An atom will seek to have 8 outer electrons by bonding or by electrons by bonding or by gaining or loosing electronsgaining or loosing electrons

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Ionic CompoundsIonic Compounds

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What is the molecular formula for:What is the molecular formula for:Sodium and ChlorineSodium and ChlorineMagnesium and ChlorineMagnesium and Chlorine

Show how each compound is Show how each compound is formedformed

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AnswersAnswers

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The EndThe End

Good Luck with the Good Luck with the Chapter 3 testChapter 3 test

Major Topics:Major Topics:

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Atomic HistoryAtomic History

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Mental Models of the AtomMental Models of the Atom

It is yet impossible to obtain a true It is yet impossible to obtain a true picture of the structure of an atompicture of the structure of an atom

Scientists are left to best guesses Scientists are left to best guesses based on observations during a based on observations during a series of experimentsseries of experiments

With each breakthrough, the With each breakthrough, the model had to changemodel had to change

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Greeks (400 B.C.) - DemocritusGreeks (400 B.C.) - Democritus

The atom is made of (+) and (-) bitsThe atom is made of (+) and (-) bits

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1808 - Dalton – Atomic Theory1808 - Dalton – Atomic Theory

ObservedObserved::Natural materials = pure Natural materials = pure

substancessubstancesPure substances are either Pure substances are either

elements or compoundselements or compoundsCompounds always have same Compounds always have same

proportions of elementsproportions of elements

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1808 - Dalton – Atomic Theory1808 - Dalton – Atomic TheoryElements are made of tiny “atoms”Elements are made of tiny “atoms”Atoms in an element are identicalAtoms in an element are identicalAtoms from one element are different Atoms from one element are different

from those of anotherfrom those of anotherAtoms can combine to form compoundsAtoms can combine to form compoundsAtoms are indivisible by chemical meansAtoms are indivisible by chemical means

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DaltonDalton

Law of constant composition – a

compound always has the same composition

MOV

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1890 – J.J. Thomson – 1890 – J.J. Thomson – Plum Pudding ModelPlum Pudding Model

Showed elements have negative pieces by Showed elements have negative pieces by repelling them with magnetic field – repelling them with magnetic field – electronelectron

Overall charge is zero – must have positive Overall charge is zero – must have positive piecespieces

Positive ball with negative pieces sprinkled Positive ball with negative pieces sprinkled inin

MOVMOV

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1913 – Ernest Rutherford1913 – Ernest Rutherford

Gold Foil ExperimentGold Foil Experiment wrapped piece of wrapped piece of gold foil with gold foil with photographic paper photographic paper and bombarded with and bombarded with alpha particlesalpha particles

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Gold Foil ExperimentGold Foil Experiment

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1913 – Ernest Rutherford1913 – Ernest RutherfordMost passed through – thus atoms Most passed through – thus atoms

are mostly empty spaceare mostly empty spaceAlpha particles slightly thrown off Alpha particles slightly thrown off

course – (+) small center - protoncourse – (+) small center - protonEmpty space contains the Empty space contains the

electronselectronsmovmov

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1913 – Ernest Rutherford1913 – Ernest Rutherford

Cloud ModelCloud Model (nuclear atom) – (nuclear atom) – Cloud of electrons surrounding a Cloud of electrons surrounding a central positive nucleuscentral positive nucleus

Nucleus is 1/100,000 of the total Nucleus is 1/100,000 of the total size (a paperclip inside a stadium)size (a paperclip inside a stadium)

MOVMOV

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1926 - Niels Bohr (planetary 1926 - Niels Bohr (planetary model)model)

Quickly re-developed to place Quickly re-developed to place electrons in well-defined paths electrons in well-defined paths around a central nucleusaround a central nucleus

MOVMOV

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Present Day:Present Day:

It is impossible to know the It is impossible to know the location of an electron at any one location of an electron at any one timetime

Scientists can generate pictures Scientists can generate pictures based on the probability of the based on the probability of the locations of the electronslocations of the electrons

MOVMOV

1 chapter 3 structure of the atom chapter 3 notes

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