Atomic Structure and The Periodic Table Mr. Chan Northwestern University To insert your company logo...

Atomic Structure and The Atomic Structure and The Periodic TablePeriodic Table

Mr. ChanMr. Chan

Northwestern UniversityNorthwestern University

Today (Day 18)Today (Day 18)

(0-10) Return/Discuss Tests(0-10) Return/Discuss Tests (10-15) Activate: Sketch Atom(10-15) Activate: Sketch Atom (15-20) Mystery Box(15-20) Mystery Box (20-30) Dalton’s Atomic Theory(20-30) Dalton’s Atomic Theory (30-43) Word Splash(30-43) Word Splash Video – WOC The Atom (30 min)Video – WOC The Atom (30 min)

ConferencesConferences

Mystery BoxesMystery Boxes

Procedure: Procedure: Select a Mystery Box. Without Select a Mystery Box. Without

opening it, try to learn about its opening it, try to learn about its contents by using all the tools of contents by using all the tools of observation available to you. Outline observation available to you. Outline your plan to determine the contents your plan to determine the contents of the box and record all of the box and record all observations you make.observations you make.

Mystery Boxes Mystery Boxes

Questions:Questions: 1. What evidence supports your 1. What evidence supports your

conclusion about the type of item conclusion about the type of item contained in the box?contained in the box?

2. What kinds of things can you do to 2. What kinds of things can you do to determine the contents of your box if you determine the contents of your box if you had access to other kinds of observational had access to other kinds of observational tools?tools?

3. Since you cannot see what is inside, 3. Since you cannot see what is inside, how can you be 100% sure of its contents?how can you be 100% sure of its contents?

What are atoms?What are atoms?

Smallest particle of element that retains properties of the Smallest particle of element that retains properties of the elementelement

Possible to see individual atomsPossible to see individual atoms Demo: Al Foil – Physical Changes – Smallest PieceDemo: Al Foil – Physical Changes – Smallest Piece

History of Atomic TheoryHistory of Atomic Theory

Original model – DemocritusOriginal model – Democritus Atomos – smallest unit of matterAtomos – smallest unit of matter

Dalton’s TheoryDalton’s Theory 1) Elements composed of tiny indivisible (not 1) Elements composed of tiny indivisible (not

invisible) particles called atomsinvisible) particles called atoms 2) Atoms of the same element are identical2) Atoms of the same element are identical 3) Atoms of different elements can chemically 3) Atoms of different elements can chemically

combine with one another in simple whole number combine with one another in simple whole number ratios (compounds)ratios (compounds)

4) In chemical reactions, atoms are separated, joined, 4) In chemical reactions, atoms are separated, joined, and rearranged. Atoms of one element are never and rearranged. Atoms of one element are never changed. changed.


(0-5) Discuss HW(0-5) Discuss HW (5-10) Demo(5-10) Demo (10-25) Experiments – discovery of Atomic Structure(10-25) Experiments – discovery of Atomic Structure (25-35) Rutherford’s Au Experiment(25-35) Rutherford’s Au Experiment (35-43, 0-25) LAB(35-43, 0-25) LAB (25-43) Numbers associated with At.Structure(25-43) Numbers associated with At.Structure

What is the structure of an atom?What is the structure of an atom?

ElectronsElectrons J.J. Thomson, cathode ray tubes – OverheadJ.J. Thomson, cathode ray tubes – Overhead

Electric current flowing through gasesElectric current flowing through gases Beam – cathode ray travels from cathode (-) to the Beam – cathode ray travels from cathode (-) to the

anode (+)anode (+) Metal plates – beam attracted to positive plateMetal plates – beam attracted to positive plate Electrons: negative, 1/2000 mass of hydrogen atomElectrons: negative, 1/2000 mass of hydrogen atom

Millikan – oil drop experimentsMillikan – oil drop experiments determined charge/mass ratio of electrondetermined charge/mass ratio of electron Mass of electron = 1/1840 mass of hydrogen atomMass of electron = 1/1840 mass of hydrogen atom

Structure cont.Structure cont.

Protons – positively charged particlesProtons – positively charged particles Needed to balance charge of electrons in atomNeeded to balance charge of electrons in atom Goldstein – CRT with loss of electrons – canal Goldstein – CRT with loss of electrons – canal

rays from cathode traveling in opposite direction rays from cathode traveling in opposite direction as electronsas electrons

Neutrons – no charge, mass - protonNeutrons – no charge, mass - proton Chadwick – knew some mass was unaccounted forChadwick – knew some mass was unaccounted for

Summary of Subatomic particlesSummary of Subatomic particles

Particle, symbol, relative charge, relative mass, Particle, symbol, relative charge, relative mass, actual massactual mass

Rutherford’s Gold Foil ExperimentRutherford’s Gold Foil Experiment

Rutherford’s Gold Foil ExperimentRutherford’s Gold Foil Experiment

Led to discovery that most of the atom is empty spaceLed to discovery that most of the atom is empty space All of the positive charge and most of the atom’s All of the positive charge and most of the atom’s

mass found in a small regionmass found in a small region Nucleus of the atomNucleus of the atom

Core that contains protons and neutronsCore that contains protons and neutrons

Models of AtomsModels of Atoms

Numbers Associated with Atomic StructureNumbers Associated with Atomic Structure

Atomic NumberAtomic Number Number of protons in nucleus of atom of elementNumber of protons in nucleus of atom of element Also equals number of electrons if electrically Also equals number of electrons if electrically

neutralneutral Determines which element you haveDetermines which element you have Practice: How many protons and electrons, what Practice: How many protons and electrons, what

the symbol, element name isthe symbol, element name is Mass numberMass number

Total number of protons and neutronsTotal number of protons and neutrons Not given on the periodic tableNot given on the periodic table

Calculating Number of Protons, Neutrons, and Calculating Number of Protons, Neutrons, and ElectronsElectrons

Number of neutrons = Mass Number – Atomic Number of neutrons = Mass Number – Atomic NumberNumber

Shorthand Notation: Mass/Atomic – ElementShorthand Notation: Mass/Atomic – Element OR Element – Mass numberOR Element – Mass number Practice #9-12: Determine number of protons, Practice #9-12: Determine number of protons,

electrons, and neutrons, completing tables of atomic electrons, and neutrons, completing tables of atomic number, mass number, #protons, #neutrons, number, mass number, #protons, #neutrons, #electrons, symbol – notation, Determining from #electrons, symbol – notation, Determining from symbol: #neutronssymbol: #neutrons


(0-5) Opener (0-5) Opener (5-15) Discuss HW(5-15) Discuss HW (15-30) Quiz(15-30) Quiz (30-43) Isotopes(30-43) Isotopes

What are Isotopes?What are Isotopes?

Atoms that have the same number of protons but different Atoms that have the same number of protons but different numbers of neutronsnumbers of neutrons

Different mass numbersDifferent mass numbers Atoms are chemically alike – behave similarlyAtoms are chemically alike – behave similarly

Common misconception: radically different – NO!Common misconception: radically different – NO! Examples: 3 isotopes of hydrogenExamples: 3 isotopes of hydrogen

Tritium – Spiderman 2 errors – MOVIE CLIPTritium – Spiderman 2 errors – MOVIE CLIP Gas, not solidGas, not solid More than 25 pounds in worldMore than 25 pounds in world

Chemical symbols, Subatomic particles examples for isotopes Chemical symbols, Subatomic particles examples for isotopes (O-16,17,18)(O-16,17,18)

Symbolic Notation - isotopesSymbolic Notation - isotopes


(0-10) Opener/Discuss HW(0-10) Opener/Discuss HW (10-15) Discuss QUIZ(10-15) Discuss QUIZ (15-20) Spiderman 2 Clip (15-20) Spiderman 2 Clip (20-30) Activity: Isotope Numbers Relay Race(20-30) Activity: Isotope Numbers Relay Race (30-43) Average Atomic Mass(30-43) Average Atomic Mass (0-43) Isotopes and Atomic Mass Lab(0-43) Isotopes and Atomic Mass Lab

Opener - 9/29Opener - 9/29

Determine the number of protons, neutrons, and Determine the number of protons, neutrons, and electrons in the following isotopes:electrons in the following isotopes: Hydrogen-1, Hydrogen-2, and Hydrogen-3Hydrogen-1, Hydrogen-2, and Hydrogen-3

What is average atomic mass?What is average atomic mass?

Weighted grades analogyWeighted grades analogy Masses of subatomic particles ridiculously small – Masses of subatomic particles ridiculously small –

needed something more convenientneeded something more convenient Arbitrary amount set: Carbon-12 atom = 12.00000 amuArbitrary amount set: Carbon-12 atom = 12.00000 amu 1 amu (atomic mass unit) = 1/12 mass of C-12 atom1 amu (atomic mass unit) = 1/12 mass of C-12 atom Mass of a single proton/neutron – 1 amuMass of a single proton/neutron – 1 amu Why are the masses decimals?Why are the masses decimals?

Most elements exist as a mixture of 2 or more Most elements exist as a mixture of 2 or more isotopesisotopes

Look at average atomic masses of elements – can you Look at average atomic masses of elements – can you speculate which isotope is most common?speculate which isotope is most common?

How do you calculate average How do you calculate average atomic mass?atomic mass?

Average atomic mass = weighted average mass of atoms in Average atomic mass = weighted average mass of atoms in naturally occurring samplenaturally occurring sampleNumber on Periodic Table – explains why we could not use as mass Number on Periodic Table – explains why we could not use as mass

numbernumberReflects both the mass and the relative abundance of the isotopes as Reflects both the mass and the relative abundance of the isotopes as

they occur in naturethey occur in nature Calculating average atomic massCalculating average atomic mass

First, example of which is closer?First, example of which is closer?Next, an example comparing to weighted average in class Next, an example comparing to weighted average in class

(grades)(grades)Finally, example using exact percentages and massesFinally, example using exact percentages and massesFinish HW/EC problemsFinish HW/EC problems

PracticePractice #14,16#14,16


Read ArticleRead Article Socratic SeminarSocratic Seminar


ReviewReview


Chapter 4 TestChapter 4 Test

Origin of Periodic TableOrigin of Periodic Table Mendeleev Mendeleev

Listed elements in columns and in order of Listed elements in columns and in order of increasing atomic massincreasing atomic mass

Elements in groups with similar propertiesElements in groups with similar properties MoseleyMoseley

Determined atomic numbersDetermined atomic numbersRearranged periodic table to current stateRearranged periodic table to current state

P-Tables OnlineP-Tables OnlineHTML TableHTML TableInteractive Periodic TableInteractive Periodic TableComic Book P-TableComic Book P-Table

Organization of Periodic Organization of Periodic TableTable

Increasing atomic numberIncreasing atomic number PeriodsPeriods

Horizontal rowsHorizontal rows GroupsGroups

Vertical columns of elementsVertical columns of elements Periodic lawPeriodic law

Repetition of chemical and physical propertiesRepetition of chemical and physical properties Representative elementsRepresentative elements

Metals (alkali, alkaline earth, transition)Metals (alkali, alkaline earth, transition)Nonmetals (halogens, noble gases)Nonmetals (halogens, noble gases)MetalloidsMetalloids

Atomic Structure and The Periodic Table Mr. Chan Northwestern University To insert your company logo...

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