Chapter 5

Chapter 5Chapter 5Atomic Structure and The Periodic TableAtomic Structure and The Periodic Table

Unit 2Unit 2

For Advanced Chemistry…For Advanced Chemistry…This starts Unit 2, which will cover This starts Unit 2, which will cover

Chapter 5 and Chapter 28.Chapter 5 and Chapter 28.Unit 3 will cover Chapters 13 and 14 for Unit 3 will cover Chapters 13 and 14 for

those who like planning ahead.those who like planning ahead.

For Chemistry…For Chemistry…You are going to do Chapter 5 totally, You are going to do Chapter 5 totally,

but only selected topics in Chapters 28, but only selected topics in Chapters 28, 13, and 1413, and 14

Objective AObjective Ahttp://sunsite.berkeley.edu/CalHistory/photos-large/seaborg.big.jpghttp://sunsite.berkeley.edu/CalHistory/photos-large/seaborg.big.jpg

A tour down memory lane from A tour down memory lane from about 400 BC to the early 1900s…about 400 BC to the early 1900s…

For a quick recap on a lot of the For a quick recap on a lot of the amazingly important discoveries amazingly important discoveries that brought chemistry from the that brought chemistry from the land of con-men practicing mere land of con-men practicing mere magic tricks to the Central magic tricks to the Central Science that it has become, see…Science that it has become, see…

Chemical History PowerPoint, Chemical History PowerPoint, available in Unit 2 on the website.available in Unit 2 on the website.

Discovered Plutonium in 1940; won Nobel Prize in 1951; had dinner with Mr. Schwartz in 1981; element 106 named in his honor in 1997 (Sg); died 1999.

Glenn T. Seaborg

Objective B: Just how Objective B: Just how small is an atom?small is an atom?

http://imagecache5.art.com/p/LRG/6/667/USYC000Z/fedex-field--washington-d-c-.jpghttp://imagecache5.art.com/p/LRG/6/667/USYC000Z/fedex-field--washington-d-c-.jpg

Has anyone been to a Has anyone been to a professional football professional football stadium or a major stadium or a major college football stadium?college football stadium?

If the nucleus of an atom If the nucleus of an atom was the size of a marble, was the size of a marble, sitting at the 50 yard line, sitting at the 50 yard line, the electrons would be the electrons would be about the size of really about the size of really little gnats (bugs) little gnats (bugs) whizzing around the top whizzing around the top rows of the upper deck. rows of the upper deck.

So then, most of the atom is just “empty space.”

Objective B: Just how Objective B: Just how small is an atom?small is an atom?

http://kara.allthingsd.com/files/2009/04/penny.jpeghttp://kara.allthingsd.com/files/2009/04/penny.jpeg

Let’s use a penny as an example Let’s use a penny as an example (picture, in slide show, is approximately (picture, in slide show, is approximately life-size). A penny, if made of pure Cu life-size). A penny, if made of pure Cu (copper) would have 2.4 x 10(copper) would have 2.4 x 102222 atoms. atoms. That’s 24,000,000,000,000,000,000,000 That’s 24,000,000,000,000,000,000,000 atoms, btw.atoms, btw.

If you lined up 100,000,000 atoms, they If you lined up 100,000,000 atoms, they would make up a line of approximately 1 would make up a line of approximately 1 cm. So, 2.4 x 10cm. So, 2.4 x 102222 atoms, if lined up atoms, if lined up would make a line that was would make a line that was approximately 2.4 x 10approximately 2.4 x 1099 KILOMETERS KILOMETERS long. long.

Approx. 1 cm from arrow to arrow (in slide show mode)

How far is that?How far is that?http://stardate.org/images/gallery/sun5.jpghttp://stardate.org/images/gallery/sun5.jpg

http://1.bp.blogspot.com/_Clz-U8TjA_0/SYQUNjRgeRI/AAAAAAAAAAU/kcQOn18_eP4/s320/http://1.bp.blogspot.com/_Clz-U8TjA_0/SYQUNjRgeRI/AAAAAAAAAAU/kcQOn18_eP4/s320/EarthBlueMarbleWestTerra.jpgEarthBlueMarbleWestTerra.jpg

2.4 x 102.4 x 1099 KILOMETERS is 8 trips KILOMETERS is 8 trips from the Earth to the Sun and back. from the Earth to the Sun and back.

By the way, it takes just over 25 By the way, it takes just over 25 pennies (25.08) to make a mole of pennies (25.08) to make a mole of Cu. That’s 63.5 grams of pennies.Cu. That’s 63.5 grams of pennies.

Scanning tunneling microscopes are Scanning tunneling microscopes are capable of seeing the surface of capable of seeing the surface of individual atoms. This is a relatively individual atoms. This is a relatively new development, within the past new development, within the past 20 years or so. Those didn’t exist 20 years or so. Those didn’t exist when I was in high school or when I was in high school or college.college.

Angstoms (Å)Angstoms (Å)http://intro.chem.okstate.edu/1314F00/Lecture/Chapter7/ATRADIID.DIR_PICT0003.gifhttp://intro.chem.okstate.edu/1314F00/Lecture/Chapter7/ATRADIID.DIR_PICT0003.gif

Even the largest atoms are very small. The diameter of a uranium atom is Even the largest atoms are very small. The diameter of a uranium atom is only about 0.345 nanometers.only about 0.345 nanometers.

A special unit is sometimes used to describe atomic dimensions, such as A special unit is sometimes used to describe atomic dimensions, such as atomic radius or atomic diameter. Note the trend as you go across a row and atomic radius or atomic diameter. Note the trend as you go across a row and down a column.down a column.

That is the Angstrom. We use a Å to represent Angstroms (That is the Angstrom. We use a Å to represent Angstroms (if you want to type if you want to type that it’s that it’s shift-alt-Ashift-alt-A on a Mac and on a Mac and control-shift-2, shift-Acontrol-shift-2, shift-A on a bogus, on a bogus, inferior, Windows or Vista based machineinferior, Windows or Vista based machine).).

Angstoms (Å)Angstoms (Å)http://upload.wikimedia.org/wikipedia/commons/1/11/Hydrogen_Atom.jpghttp://upload.wikimedia.org/wikipedia/commons/1/11/Hydrogen_Atom.jpg

Even the largest atoms are Even the largest atoms are very small. The diameter of very small. The diameter of a uranium atom is only a uranium atom is only about 0.345 nanometers.about 0.345 nanometers. 0.345 nm = 3.45Å0.345 nm = 3.45Å 1nm = 10Å1nm = 10Å 1Å = 1 x 101Å = 1 x 10-10-10 meters meters

A hydrogen atom is the A hydrogen atom is the smallest atom. H has a smallest atom. H has a diameter of only 0.74Å. diameter of only 0.74Å. About 13.5 billion hydrogen About 13.5 billion hydrogen atoms could fit onto the atoms could fit onto the edge of a meter stick.edge of a meter stick.

Isotopes

What does an atom look What does an atom look like?like?

http://www.lanl.gov/orgs/pa/newsbulletin/images/Isotopes_logo.jpghttp://www.lanl.gov/orgs/pa/newsbulletin/images/Isotopes_logo.jpg

In your notes, draw In your notes, draw a simple picture of a simple picture of an atom. How an atom. How about Lithium.about Lithium.

What did you draw? What did you draw?

AAA baseball club Albuquerque Isotopes logo (you need to know what isotopes are!)

AtomsAtomshttp://upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Stylised_Lithium_Atom.svg/270px-http://upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Stylised_Lithium_Atom.svg/270px-

Stylised_Lithium_Atom.svg.pngStylised_Lithium_Atom.svg.pnghttp://www.solarsystempictures.net/http://www.solarsystempictures.net/

Most people probably drew Most people probably drew a nucleus of some type a nucleus of some type with electrons orbiting with electrons orbiting around it.around it.

Possibly it looks a little like Possibly it looks a little like a mini solar system.a mini solar system.

Atoms are composed ofAtoms are composed of ProtonsProtons NeutronsNeutrons ElectronsElectrons

NeutronProtonElectron

Lithium

Sun=Nucleus

Planets=Electrons

Subatomic ParticlesSubatomic Particles

Particle Relative charge Relative mass(1 amu = mass of a proton)

Actual Mass of Particle

Proton+1 1 amu 1.67 x 10-24g

Neutron0 1 amu 1.67 x 10-24g

Electron-1 0 amu 9.11 x 10-28g

ElectronsElectrons

Electrons were the first particle discovered.Electrons were the first particle discovered.

JJ Thompson discovered the electron using cathode JJ Thompson discovered the electron using cathode ray tubes, and modified the model of the atom ray tubes, and modified the model of the atom because of this discovery.because of this discovery.

The electron has a very small mass. It is actually The electron has a very small mass. It is actually 1/1840th the size of a proton (0.00054 times). In 1/1840th the size of a proton (0.00054 times). In other words, if an electron was a smidge over a other words, if an electron was a smidge over a pound, protons and neutrons would weigh almost a pound, protons and neutrons would weigh almost a TON.TON.

ElectronsElectronshttp://educar.sc.usp.br/licenciatura/2003/mi/Millikan-Oil-Drop-Apparatus.gifhttp://educar.sc.usp.br/licenciatura/2003/mi/Millikan-Oil-Drop-Apparatus.gif

Since it’s so small relative to a proton, we say that it has a relative Since it’s so small relative to a proton, we say that it has a relative mass of 0.mass of 0.

Electrons are negatively charged. Each electron has a charge of -1. Electrons are negatively charged. Each electron has a charge of -1. (Don’t forget the negative…it’s important!)(Don’t forget the negative…it’s important!)

If an atom loses an electron, what remains will have a positive If an atom loses an electron, what remains will have a positive charge. If an atom gains an electron, it will have a negative charge.charge. If an atom gains an electron, it will have a negative charge.

Robert Millikan measured the charge of the electron in “The Oil Drop Experiments”

This is what he used to do it…

ProtonsProtonshttp://web.buddyproject.org/web017/web017/images/atom.JPGhttp://web.buddyproject.org/web017/web017/images/atom.JPG

Protons were the next Protons were the next subatomic particle to be subatomic particle to be discovered. discovered.

Protons were discovered by E. Protons were discovered by E. Goldstein.Goldstein.

Protons have a relative mass Protons have a relative mass of 1 and a charge of +1.of 1 and a charge of +1.

ProtonsProtonshttp://www.periodictable.com/Items/020.6/index.htmlhttp://www.periodictable.com/Items/020.6/index.html

Protons determine the “identity” Protons determine the “identity” of an atom. The number of of an atom. The number of protons is a property called protons is a property called “atomic number.” Atomic “atomic number.” Atomic numbers are on the periodic table.numbers are on the periodic table.

The number of protons determines The number of protons determines what kind of atom it is.what kind of atom it is. H has 1 protonH has 1 proton C has 6 protonsC has 6 protons U has 92 protonsU has 92 protons

Atomic Number

ProtonsProtons

Neutral atoms have the same number of Neutral atoms have the same number of protons and electrons. (Makes sense, right?)protons and electrons. (Makes sense, right?)

The charges balance each other out. (Ca has The charges balance each other out. (Ca has 20 protons, and must have 20 negatively-20 protons, and must have 20 negatively-charged electrons to balance out those charged electrons to balance out those positive charges)positive charges)

Protons are located in the nucleus of the Protons are located in the nucleus of the atom. (Where are the electrons?)atom. (Where are the electrons?)

NeutronsNeutronshttp://www.ct.infn.it/~rivel/Archivio/chadwick.jpghttp://www.ct.infn.it/~rivel/Archivio/chadwick.jpg

http://kwisp.files.wordpress.com/2009/05/adventures-jimmy-neutron-300-032707.jpghttp://kwisp.files.wordpress.com/2009/05/adventures-jimmy-neutron-300-032707.jpg

Neutrons are also located in the Neutrons are also located in the nucleus of the atom.nucleus of the atom.

The nucleus was discovered by The nucleus was discovered by Ernest Rutherford, a former Ernest Rutherford, a former student of JJ Thompson.student of JJ Thompson.

The neutron was the last particle The neutron was the last particle discovered, by James Chadwick, a discovered, by James Chadwick, a former student of Rutherford.former student of Rutherford.

Ooops, wrong neutron!

Chadwick

NeutronsNeutrons

More than likely, the fact that neutrons had no More than likely, the fact that neutrons had no charge made it harder to discover.charge made it harder to discover.

The neutron has a relative mass of 1, the same as The neutron has a relative mass of 1, the same as a proton. However, it has no charge. Therefore, a proton. However, it has no charge. Therefore, we say that the charge = 0.we say that the charge = 0.

The actual mass of a neutron is almost the same The actual mass of a neutron is almost the same as that of a proton. It is slightly differentas that of a proton. It is slightly different P = 0.0000000000000000000000016726 gP = 0.0000000000000000000000016726 g N = 0.0000000000000000000000016749 gN = 0.0000000000000000000000016749 g

Golf Balls In BeakersGolf Balls In BeakersMy Little Model of the AtomMy Little Model of the Atom

http://www.vias.org/physics/bk4_03_02.htmlhttp://www.vias.org/physics/bk4_03_02.html

These are in the lab somewhere. Find them.These are in the lab somewhere. Find them.

The pink balls represent protons.The pink balls represent protons.

The white balls represent neutrons.The white balls represent neutrons.

Scientists quickly figured out by Scientists quickly figured out by experimentation how many protons each experimentation how many protons each element had. If you want to read more, element had. If you want to read more, check out the link above. Basically though….check out the link above. Basically though….

Golf Balls In BeakersGolf Balls In Beakers

They were able to ionize (remove electrons—all of them) and They were able to ionize (remove electrons—all of them) and found that found that

Hydrogen had 1 proton. They figured this out because they Hydrogen had 1 proton. They figured this out because they were able to make Hwere able to make H++ but not H but not H2+2+

Helium had 2 protons. Again, they were able to make HeHelium had 2 protons. Again, they were able to make He++ and and HeHe2+2+ BUT NOT He BUT NOT He3+3+

Lithium had 3 protons.Lithium had 3 protons.

Magnesium had 12 protons.Magnesium had 12 protons.

Bromine had 35 protons.Bromine had 35 protons.

Uranium had 92 protons. For the heavier elements, they were Uranium had 92 protons. For the heavier elements, they were not able to remove all of the electrons. They had to do other not able to remove all of the electrons. They had to do other experiments to figure that out, using a ratio of a known atomic experiments to figure that out, using a ratio of a known atomic number and an unknown one.number and an unknown one.


Not all the calculations were accurate at first, but Not all the calculations were accurate at first, but they figured them out in time.they figured them out in time.

Scientists also knew what the masses of the Scientists also knew what the masses of the elements were, and the numbers weren’t adding elements were, and the numbers weren’t adding up.up.

Hydrogen was OK. It seemed to work out.Hydrogen was OK. It seemed to work out.

But helium should weigh twice as much as But helium should weigh twice as much as hydrogen. And lithium should weigh three times hydrogen. And lithium should weigh three times as much. And carbon should weigh 6 times as as much. And carbon should weigh 6 times as much.much.


But they didn’t.But they didn’t.

Helium was actually 4 times as heavy as Helium was actually 4 times as heavy as hydrogen. Lithium was 7 times as heavy. hydrogen. Lithium was 7 times as heavy. Carbon was 12 times as heavy.Carbon was 12 times as heavy.

And that was very confusing. However, the And that was very confusing. However, the neutron provided the final piece of the neutron provided the final piece of the puzzle. The neutrons accounted for the puzzle. The neutrons accounted for the missing mass.missing mass.

NeutronsNeutrons

It turns out that Helium has 2 protons AND It turns out that Helium has 2 protons AND 2 neutrons, which makes it 4 times as 2 neutrons, which makes it 4 times as heavy as hydrogen.heavy as hydrogen.

Lithium has 3 protons and 4 neutrons, Lithium has 3 protons and 4 neutrons, which makes it 7 times as heavy as which makes it 7 times as heavy as hydrogen.hydrogen.

Carbon has 6 protons and 6 neutrons, which Carbon has 6 protons and 6 neutrons, which makes it 12 times as heavy as hydrogen.makes it 12 times as heavy as hydrogen.

The numbers added up.The numbers added up.

The NucleusThe Nucleushttp://www.chemicalelements.com/bohr/b0019.gifhttp://www.chemicalelements.com/bohr/b0019.gif

Since the neutrons are located in the Since the neutrons are located in the nucleus, with the protons, nucleus, with the protons, substantially ALL of the mass of the substantially ALL of the mass of the atom is contained within the nucleus.atom is contained within the nucleus.

Mass of nucleus in diagram Mass of nucleus in diagram 0.0000000000000000000000651 g0.0000000000000000000000651 g

Mass of electrons Mass of electrons 0.0000000000000000000000000173 0.0000000000000000000000000173 gg

In other words, if the nucleus In other words, if the nucleus weighed 651 pounds, the electrons weighed 651 pounds, the electrons (combined) would weigh less than a (combined) would weigh less than a McD’s quarter-pounder patty.McD’s quarter-pounder patty.

What element is this??

Strong Nuclear ForceStrong Nuclear Force

But positively charged things repel other But positively charged things repel other positively charged things, right?positively charged things, right?

Why do all the protons stick together in the Why do all the protons stick together in the nucleus?nucleus?

Why doesn’t it just spontaneously break Why doesn’t it just spontaneously break apart?apart?

Strong Nuclear ForceStrong Nuclear Forcehttp://www.antonine-education.co.uk/Physics_AS/Module_1/Topic_5/strong_force.jpghttp://www.antonine-education.co.uk/Physics_AS/Module_1/Topic_5/strong_force.jpg

The answer is strong nuclear force. The answer is strong nuclear force.

It’s the strongest known force in the It’s the strongest known force in the universe. It far, far stronger than universe. It far, far stronger than gravity.gravity.

It only can be felt when the particles are It only can be felt when the particles are extremely close together, like when extremely close together, like when they are packed together in the they are packed together in the nucleus.nucleus.

Protons and neutrons are made of Protons and neutrons are made of quarks. It’s thought that the quarks quarks. It’s thought that the quarks attract other quarks and hold the attract other quarks and hold the nucleus together, even though all of the nucleus together, even though all of the protons are positively charged and protons are positively charged and would otherwise repel each other.would otherwise repel each other.

The secret’s in the attractions between the quarks…

Objective DObjective Dhttp://www.fiu.edu/~zhangj/cartoon_quantum3.gifhttp://www.fiu.edu/~zhangj/cartoon_quantum3.gif

Scientists, starting with Scientists, starting with Dalton, came up with Dalton, came up with models of the atom, to models of the atom, to help understand it and help understand it and help to predict its help to predict its behavior.behavior.

Check out the Chemical Check out the Chemical History power point for History power point for more details as the model more details as the model evolved over about 130 evolved over about 130 years from Dalton to years from Dalton to Quantum Mechanics.Quantum Mechanics.

Objective EObjective E

We already know that the number We already know that the number of protons is what makes an atom of protons is what makes an atom unique.unique.

Hydrogen has 1 proton.Hydrogen has 1 proton.

Carbon has 6 protons.Carbon has 6 protons.

Uranium has 92 protons.Uranium has 92 protons.

The “atomic number” is the number The “atomic number” is the number of protons. We sometimes use a Z of protons. We sometimes use a Z to represent atomic number.to represent atomic number.

So, if “ProtonMan” was a superhero, he’d have a “Z” on his suit??

Objective EObjective E

So, for hydrogen, Z = 1So, for hydrogen, Z = 1

For carbon, Z = 6For carbon, Z = 6

For uranium, Z = 92.For uranium, Z = 92.

What is the atomic number for What is the atomic number for AluminumAluminum ZincZinc ChlorineChlorine

Don’t memorize these…they are on the Periodic Table

Find THEM!!

Objective FObjective F

So, Z (atomic number) tells us how many So, Z (atomic number) tells us how many protons an atom hasprotons an atom has.. It does NOT It does NOT tell you how many ELECTRONS tell you how many ELECTRONS you have (accurately) all the you have (accurately) all the time!time!

Most atoms have no charge. That Most atoms have no charge. That means that the number of protons means that the number of protons (which are positively charged) must (which are positively charged) must balance out the number of electrons balance out the number of electrons (which are negatively charged). (which are negatively charged).


Unless you are TOLD that the atom has a charge, Unless you are TOLD that the atom has a charge, you should assume it has you should assume it has no chargeno charge, and , and therefore, # of protons = # of electrons.therefore, # of protons = # of electrons.

Hydrogen (Z = 1) also has one electron.Hydrogen (Z = 1) also has one electron. Lithium (Z = 3) also has 3 electrons.Lithium (Z = 3) also has 3 electrons. Carbon (Z = 6) also has 6 electrons.Carbon (Z = 6) also has 6 electrons. Uranium (Z =92) also has 92 electrons.Uranium (Z =92) also has 92 electrons.

BUT REMEMBERBUT REMEMBER The numbers of protons The numbers of protons doesn’t always equal the numbers of electrons. doesn’t always equal the numbers of electrons.


Some atoms can lose electrons. When they Some atoms can lose electrons. When they do so, they will form a positive “ion.” Some do so, they will form a positive “ion.” Some atoms can gain electrons. When they do so, atoms can gain electrons. When they do so, they will form a negative “ion.” they will form a negative “ion.”

An ion is a atom which has an electrical An ion is a atom which has an electrical charge (either positive or negative). We’ll get charge (either positive or negative). We’ll get to those in Chapter 6. Nato those in Chapter 6. Na+1+1 and Cl and Cl-1-1 are are formulas for ions.formulas for ions.

The number of protons cannot change. If the The number of protons cannot change. If the number of protons changes, it’s no longer the number of protons changes, it’s no longer the same element. same element. Atoms can gain or lose Atoms can gain or lose electrons, but they can NOT gain or lose electrons, but they can NOT gain or lose protons in any chemical reaction.protons in any chemical reaction.

Schwartz’s LawSchwartz’s Law(a law I made up…hey, it’s my (a law I made up…hey, it’s my

class)class)

To calculate the number of electrons, use To calculate the number of electrons, use

# of Electrons = Z – IC# of Electrons = Z – IC Where Z = atomic number and IC = ionic charge.Where Z = atomic number and IC = ionic charge.

Ex: Suppose we have a sodium ion with a + Ex: Suppose we have a sodium ion with a + 1 charge. How many electrons does it have? 1 charge. How many electrons does it have? Atomic number (Z) is 11 (find this on Periodic Atomic number (Z) is 11 (find this on Periodic Table) and ionic charge is 1.Table) and ionic charge is 1.

# electrons = 11 - 1 = 10# electrons = 11 - 1 = 10

Schwartz’s LawSchwartz’s Law

Let’s calculate a couple more…Let’s calculate a couple more…

Ex: Suppose we have a sulfur ion with a - 2 Ex: Suppose we have a sulfur ion with a - 2 charge. How many electrons does it have? charge. How many electrons does it have? Atomic number (Z) is 16 and ionic charge is -2.Atomic number (Z) is 16 and ionic charge is -2. # electrons = 16 - (-2) = 16 + 2 = 18# electrons = 16 - (-2) = 16 + 2 = 18

Ex: Suppose we have an zinc atom with no Ex: Suppose we have an zinc atom with no charge. How many electrons does it have? charge. How many electrons does it have? Atomic number (Z) is 30 and ionic charge is 0.Atomic number (Z) is 30 and ionic charge is 0. # electrons = 30 - 0 = 30# electrons = 30 - 0 = 30

Objective FObjective Fhttp://www.atomicarchive.com/Physics/Images/isotopes.jpghttp://www.atomicarchive.com/Physics/Images/isotopes.jpg

How do we calculate how How do we calculate how many neutrons we have?many neutrons we have?

In order to do that, we need to In order to do that, we need to look at another property, look at another property, called atomic mass. called atomic mass. The The atomic mass of an atom = atomic mass of an atom = THE SUM of protons and THE SUM of protons and neutrons.neutrons.

We will use another formulaWe will use another formula # Neutrons = A – Z# Neutrons = A – Z A = Mass NumberA = Mass Number So, what is Z again?So, what is Z again?

Hey these are isotopes again. Isotope = same # of protons but a different # of neutrons.

6 neutrons

8 neutrons

Objective FObjective Fhttp://www.lbl.gov/abc/Basic.html#Nuclearstructurehttp://www.lbl.gov/abc/Basic.html#Nuclearstructure

Let’s look at an example. An atom of Let’s look at an example. An atom of Bromine (Br-80) has Z = 35 and Mass Bromine (Br-80) has Z = 35 and Mass Number = 80. How many neutrons Number = 80. How many neutrons does it have? (does it have? (Br-80 doesn’t mean Br-80 doesn’t mean bromine with a charge of -80. When bromine with a charge of -80. When they write it like that, it’s a DASH and they write it like that, it’s a DASH and 80 is the mass number80 is the mass number))

# Neutrons = Mass Number - # Neutrons = Mass Number - Atomic NumberAtomic Number # Neutrons = 80 - 35 = 45# Neutrons = 80 - 35 = 45


An atom of Deuterium has Z = 1, and An atom of Deuterium has Z = 1, and Mass Number = 2. How many neutrons Mass Number = 2. How many neutrons does it have?does it have?

Since Z = 1, deuterium must be some Since Z = 1, deuterium must be some type of hydrogen. Hydrogen has Z = 1, type of hydrogen. Hydrogen has Z = 1, and since every element has a unique and since every element has a unique number of protons, no two elements number of protons, no two elements can have the same number of protons.can have the same number of protons.

Deuterium is a form of hydrogen. When Deuterium is a form of hydrogen. When deuterium reacts with oxygen it forms deuterium reacts with oxygen it forms something called “heavy water.” something called “heavy water.” Heavy water is represented with the Heavy water is represented with the formula Dformula D22O.O. # of Neutrons = Mass Number - Z = # of Neutrons = Mass Number - Z =

2 - 1 = 12 - 1 = 1

Isotopes of hydrogen:

1H = hydrogen

1 proton, 0 neutron

2H = deuterium

1 proton, 1 neutron

3H = tritium

1 proton, 2 neutrons

Hydrogen is the only element with special names for isotopes.

Special note

Power Point AssignmentPower Point Assignment

Pick an element…any element…Pick an element…any element…

Well, not just any element. Pick an element Well, not just any element. Pick an element whose symbol begins with the same letter as your whose symbol begins with the same letter as your first name.first name.

If for some strange reason none exists, say for If for some strange reason none exists, say for instance your name is Julie or Joe (sorry, no J instance your name is Julie or Joe (sorry, no J elements) than use the next letter.elements) than use the next letter. So Julie could pick UraniumSo Julie could pick Uranium And Joe could pick OsmiumAnd Joe could pick Osmium

Research your element and write a 150 word Research your element and write a 150 word summary on what you learned.summary on what you learned.

Objective GObjective Ghttp://www.usagold.com/images/gold-coins-images.jpeghttp://www.usagold.com/images/gold-coins-images.jpeg

http://finestimaginary.com/shop/images/medium/jewellery/au_MED.jpghttp://finestimaginary.com/shop/images/medium/jewellery/au_MED.jpg

How do isotopes differ from How do isotopes differ from each other? (each other? (You should know You should know this by now).this by now).

Look at gold (Au) on the Look at gold (Au) on the periodic table. It says that the periodic table. It says that the mass = 196.967. Since mass mass = 196.967. Since mass number and atomic number number and atomic number are ALWAYS whole numbers, are ALWAYS whole numbers, how do we get .967?how do we get .967?

The answer is that the atomic The answer is that the atomic masses on the periodic table masses on the periodic table are averages.are averages.

Objective GObjective G

They get that average atomic mass for Au by They get that average atomic mass for Au by taking into account ALL of gold’s isotopes.taking into account ALL of gold’s isotopes.

Isotopes differ from each other in the number Isotopes differ from each other in the number of neutrons. They behave the same of neutrons. They behave the same CHEMICALLY because all isotopes of the same CHEMICALLY because all isotopes of the same element have the same number of protons.element have the same number of protons.

The study guide talks about water and heavy The study guide talks about water and heavy water. Heavy water is the same as water, water. Heavy water is the same as water, except that instead of H-1 it is formed using H-except that instead of H-1 it is formed using H-2, which is sometimes called deuterium. So 2, which is sometimes called deuterium. So while water has a molar mass of 18, while water has a molar mass of 18, deuterium oxide or heavy water has a mass of deuterium oxide or heavy water has a mass of 20 (2 + 2 + 16)20 (2 + 2 + 16)

Objective GObjective Ghttp://www.damninteresting.net/content/heavy_water_ice.jpghttp://www.damninteresting.net/content/heavy_water_ice.jpg

Here’s an interesting fact…Here’s an interesting fact…

Ice cubes made out of “heavy Ice cubes made out of “heavy water” will not float. They sink to water” will not float. They sink to the bottom. So it has different the bottom. So it has different physical properties.physical properties.

Although it PROBABLY tastes the Although it PROBABLY tastes the same, you should NOT drink it same, you should NOT drink it though. Too much of it can really though. Too much of it can really mess up your system.mess up your system.

Objective GObjective G

You can purchase DYou can purchase D22O. For $33 (for 2 ounces), you can O. For $33 (for 2 ounces), you can purchase some from a company to be used as a “hydrating purchase some from a company to be used as a “hydrating product” for your skin. It’s enriched with deuterium product” for your skin. It’s enriched with deuterium (meaning it has more in it than just normal water). It’s (meaning it has more in it than just normal water). It’s doubtful, in my opinion, that it does anything special, but if doubtful, in my opinion, that it does anything special, but if you have a different hypothesis, and $33 to burn, there’s a you have a different hypothesis, and $33 to burn, there’s a link in your study guide.link in your study guide.

You can also purchase very pure heavy water as a scientific You can also purchase very pure heavy water as a scientific reagent. We call that deuterium oxide, because a real reagent. We call that deuterium oxide, because a real chemist would never order something that was called chemist would never order something that was called “heavy water.” It sells for $330 for 250g (which is about 2/3 “heavy water.” It sells for $330 for 250g (which is about 2/3 of a can of soda). This stuff has been scientifically analyzed of a can of soda). This stuff has been scientifically analyzed to contain 99.8% (at least) of Dto contain 99.8% (at least) of D22O, which is why it’s a lot O, which is why it’s a lot more expensive than the “hydrating product” for your skin.more expensive than the “hydrating product” for your skin.

Don’t drink the HEAVY water!

Objective HObjective H

How do we calculate the average How do we calculate the average atomic mass?atomic mass?

To do so, you need to know 2 To do so, you need to know 2 things:things:All possible isotopes for an elementAll possible isotopes for an elementThe percent abundance for each (in The percent abundance for each (in

other words, how much of the whole other words, how much of the whole is represented by each isotope).is represented by each isotope).

Math Alert


Let’s look at an example:Let’s look at an example:Chlorine has 2 isotopesChlorine has 2 isotopes

3535Cl which is 75.77% of the total Cl which is 75.77% of the total amount of chlorine.amount of chlorine.

3737Cl which is 24.23% of the total Cl which is 24.23% of the total amount of chlorine.amount of chlorine.

What is the average atomic What is the average atomic mass of Chlorine?mass of Chlorine?


Cl-35 accounts for 75.77% of the total chlorine. CL-37 Cl-35 accounts for 75.77% of the total chlorine. CL-37 accounts for the rest. accounts for the rest.

Remember to convert percents into decimals, Remember to convert percents into decimals, you have to move the decimal point 2 places to you have to move the decimal point 2 places to the left.the left.

You then mutiply the You then mutiply the percentage percentage (in decimal form) (in decimal form) times the times the mass number mass number for that isotope. You do that for that isotope. You do that for the other isotope too, and then add the answers for the other isotope too, and then add the answers together.together.

Avg Atomic Mass = Avg Atomic Mass = 3535 ( (0.75770.7577) + 37 (0.2423). ) + 37 (0.2423).

Avg Atomic Mass = 26.52 + 8.97 Avg Atomic Mass = 26.52 + 8.97 = 35.49= 35.49


In our class, we are always going to In our class, we are always going to round average atomic masses to 1 round average atomic masses to 1 decimal place.decimal place.

So, we’ll round 35.49 to 35.5 and that’s So, we’ll round 35.49 to 35.5 and that’s the average atomic mass of Chlorine the average atomic mass of Chlorine that we’ll use.that we’ll use.

Why can’t you just average 35 and 37 Why can’t you just average 35 and 37 (the two isotopes) and get 36 as the (the two isotopes) and get 36 as the average atomic mass? Why is that average atomic mass? Why is that wrong?wrong?

The Periodic TableThe Periodic Table

We’ve described the Periodic Table asWe’ve described the Periodic Table asThe biggest cheat sheet in scienceThe biggest cheat sheet in scienceThe best tool we have in ChemistryThe best tool we have in ChemistryYour best friend on the testYour best friend on the test

Suppose we didn’t have a Periodic Suppose we didn’t have a Periodic Table. You would have to memorize Table. You would have to memorize every fact about every element.every fact about every element.

This is a map…This is a map…

What does it tell you?What does it tell you?

It shows you the states. If you know approximately It shows you the states. If you know approximately where Virginia is, you can easily find it on the map.where Virginia is, you can easily find it on the map.

It shows you state abbreviations. If you don’t know It shows you state abbreviations. If you don’t know where Virginia is, or even what it sort of looks like, where Virginia is, or even what it sort of looks like, you can find it by using the abbreviation “VA.”you can find it by using the abbreviation “VA.”

It shows you data for each state…It shows you data for each state… The name of the state capital.The name of the state capital. The approximate location of the state capitalThe approximate location of the state capital What other states are above, below or next to each What other states are above, below or next to each

state.state. The sizes of the states..which are large and which are The sizes of the states..which are large and which are

smaller.smaller.

What else does it tell What else does it tell you?you?

http://www.destination360.com/maps/virginia-map.gifhttp://www.destination360.com/maps/virginia-map.gif

Well, that’s about all, really.Well, that’s about all, really.

But you can make some assumptions But you can make some assumptions about the states based on their about the states based on their position on the map.position on the map.

For example, VA borders NC, MD, TN, For example, VA borders NC, MD, TN, WV and KY. You might assume that WV and KY. You might assume that VA has some things in common with VA has some things in common with each of these states.each of these states.

You would be right. You would be right.

Anything else?Anything else?http://wwp.greenwichmeantime.com/images/usa/montana.jpghttp://wwp.greenwichmeantime.com/images/usa/montana.jpg

You might also assume that You might also assume that Virginia doesn’t have much in Virginia doesn’t have much in common with WY, MT, ID or OR. All common with WY, MT, ID or OR. All of these are large western states. of these are large western states. How is Virginia different from How is Virginia different from these?these?

It’s smaller in terms of area. It’s smaller in terms of area. Montana is the 4Montana is the 4thth largest @ largest @ 147,000 mi147,000 mi22 and Virginia is 35 and Virginia is 35thth largest @ less than 43,000 milargest @ less than 43,000 mi22

It’s much larger in terms of It’s much larger in terms of population. Virginia is 12population. Virginia is 12thth largest largest with just over 7 million people. with just over 7 million people. Montana is 44Montana is 44thth largest with just largest with just over 900,000 people. To put that over 900,000 people. To put that into perspective, four cities in into perspective, four cities in Virginia (Virginia Beach, Norfolk, Virginia (Virginia Beach, Norfolk, Arlington and Fredericksburg) have Arlington and Fredericksburg) have as many people as Montana.as many people as Montana.

What does this have to What does this have to do with Chemistry?do with Chemistry?

Not a lot. Not a lot.

Except that the Periodic Table of the Elements is a Except that the Periodic Table of the Elements is a lot like a map to guide you through Chemistry.lot like a map to guide you through Chemistry.

Like the US map, it divides the territory not into Like the US map, it divides the territory not into states, but elements. Elements that border other states, but elements. Elements that border other elements have more in common with each other elements have more in common with each other than elements that are on opposite sides of the than elements that are on opposite sides of the table.table.

If you can’t read a map, you might get lost on a trip. If you can’t read a map, you might get lost on a trip. And if you can’t understand the Periodic Table, you And if you can’t understand the Periodic Table, you might get lost on your trip through Chemistry.might get lost on your trip through Chemistry.

Objective IObjective I

Suppose we didn’t have a Periodic Table. You Suppose we didn’t have a Periodic Table. You would have to memorize every fact about every would have to memorize every fact about every element.element.

You would have to memorize every symbol.You would have to memorize every symbol.

You would have to memorize atomic numbers.You would have to memorize atomic numbers.

You would have to memorize atomic mass.You would have to memorize atomic mass.

You would have to memorize which elements You would have to memorize which elements behaved similarly to other elements. behaved similarly to other elements.

And, a whole lot more.And, a whole lot more.

Objective IObjective Ihttp://chemheritage.org/pubs/ch-v25n1-articles/images/mendeleev.jpghttp://chemheritage.org/pubs/ch-v25n1-articles/images/mendeleev.jpg

That’s what scientists did for many That’s what scientists did for many years.years.

However, a Russian chemist named However, a Russian chemist named Dmitri Mendeleev changed all that for Dmitri Mendeleev changed all that for us.us.

He had the bright idea to try and He had the bright idea to try and organize all the known elements (back organize all the known elements (back then, about 70 of them were known) then, about 70 of them were known) into some kind of logical order.into some kind of logical order.

Mendeleev didn’t know about atomic Mendeleev didn’t know about atomic number. Protons hadn’t been number. Protons hadn’t been discovered yet. However, he did know discovered yet. However, he did know atomic mass. Soooo, he organized his atomic mass. Soooo, he organized his table by atomic mass.table by atomic mass.

Dmitri Mendeleev


Just putting them into some kind of logical Just putting them into some kind of logical order isn’t that much of an order isn’t that much of an accomplishment. Many people could have accomplishment. Many people could have done that. (done that. (In fact, others did, but prior to In fact, others did, but prior to Mendeleev, no one got it exactly right.Mendeleev, no one got it exactly right.))

But Mendeleev left “holes” in the table to But Mendeleev left “holes” in the table to represent undiscovered elements. For represent undiscovered elements. For example, the element under aluminum example, the element under aluminum hadn’t been discovered yet. He called that hadn’t been discovered yet. He called that eka-Aluminum. Eka was a prefix which eka-Aluminum. Eka was a prefix which meant below.meant below.

He also called the element under silicon He also called the element under silicon eka-Silicon.eka-Silicon.

Nothing “fit” into the holes, so he left them blank, and he essentially challenged the rest of the world to find them.


But many people could have left holes for “still But many people could have left holes for “still undiscovered” elements. I’m still not that impressed. undiscovered” elements. I’m still not that impressed. (Although to be honest, scientists at the time snickered (Although to be honest, scientists at the time snickered at Mendeleev’s “boldness” in suggesting that his table at Mendeleev’s “boldness” in suggesting that his table would be correct, if only people would discover some would be correct, if only people would discover some new elements to put in the holes.)new elements to put in the holes.)

But he went even further. Using his new table, he But he went even further. Using his new table, he “predicted” that when those elements were discovered, “predicted” that when those elements were discovered, they would have certain types of properties.they would have certain types of properties.

He predicted the boiling point, melting point, density, He predicted the boiling point, melting point, density, color, etc. And you know what: when eka-Aluminum color, etc. And you know what: when eka-Aluminum was finally discovered, he was right!was finally discovered, he was right!

OK, now that impresses me. That takes guts. Not only OK, now that impresses me. That takes guts. Not only did he suggest that new elements would be discovered, did he suggest that new elements would be discovered, but he even predicted how they would look and behave.but he even predicted how they would look and behave.

Objective IObjective Ihttp://upload.wikimedia.org/wikipedia/commons/d/dd/Henry_Moseley.jpghttp://upload.wikimedia.org/wikipedia/commons/d/dd/Henry_Moseley.jpg

Eka-Aluminum is actually Gallium (Ga). Eka-Aluminum is actually Gallium (Ga). Eka-Silicon is Germanium (Ge).Eka-Silicon is Germanium (Ge).

That’s what Mendeleev did. And after That’s what Mendeleev did. And after the “holes” started to get filled in, just the “holes” started to get filled in, just as Mendeleev had predicted, there was as Mendeleev had predicted, there was no more snickering.no more snickering.

But remember, the table was organized But remember, the table was organized by atomic MASS, not atomic number.by atomic MASS, not atomic number.

After the discovery of the proton, After the discovery of the proton, another chemist, Henry Moseley, another chemist, Henry Moseley, revised Mendeleev’s table slightly so revised Mendeleev’s table slightly so that it was listed in atomic number that it was listed in atomic number order. That’s the table we have today.order. That’s the table we have today.

Objective JObjective Jhttp://www.dayah.com/periodic/Images/periodic%20table.pnghttp://www.dayah.com/periodic/Images/periodic%20table.png

A LITTLE PERIODIC GEOGRAPHY…A LITTLE PERIODIC GEOGRAPHY…

Rows on the Periodic Table are called PERIODS.Rows on the Periodic Table are called PERIODS.

Columns on the Periodic Table are called GROUPS or FAMILIESColumns on the Periodic Table are called GROUPS or FAMILIES

PeriodsGroups

Objective JObjective J

Group IA (1) = Alkali MetalsGroup IA (1) = Alkali Metals

Group IIA (2) = Alkaline Earth MetalsGroup IIA (2) = Alkaline Earth Metals

Group VIIA (17) = HalogensGroup VIIA (17) = Halogens

Group VIIIA (18 or 0) = Noble GasesGroup VIIIA (18 or 0) = Noble Gases

Group IB (Cu, Ag, Au) is sometimes called the Group IB (Cu, Ag, Au) is sometimes called the Royal Family.Royal Family.


Groups IA - VIIIA form the REPRESENTATIVE Groups IA - VIIIA form the REPRESENTATIVE ELEMENTS (orange on my board)ELEMENTS (orange on my board)

Groups IB - VIIIB form the TRANSITION Groups IB - VIIIB form the TRANSITION METALS (black on my board)METALS (black on my board)

The two rows underneath the table are called The two rows underneath the table are called the Lanthanides (top) and the Actinides the Lanthanides (top) and the Actinides (bottom; it was Glenn Seaborg who came up (bottom; it was Glenn Seaborg who came up with the concept that the actinides behaved with the concept that the actinides behaved like the lanthanides).like the lanthanides).


The table can be divided into 4 blocks.The table can be divided into 4 blocks.

The “s block” is Group IA, IIA and He. (2 orange rows The “s block” is Group IA, IIA and He. (2 orange rows on left + Helium)on left + Helium)

The “p block” is Groups IIIA - VIIIA (6 orange rows on The “p block” is Groups IIIA - VIIIA (6 orange rows on right, not including Helium)right, not including Helium)

The “d block” is the transition metals (the black The “d block” is the transition metals (the black section)section)

The “f block” is the Lanthanides and Actinides.The “f block” is the Lanthanides and Actinides.

The jagged line separates the metals from the The jagged line separates the metals from the nonmetals. Metals are to the left and are MOST of nonmetals. Metals are to the left and are MOST of the table. Nonmetals are to the right. It’s important the table. Nonmetals are to the right. It’s important to know what’s a metal and what’s not.to know what’s a metal and what’s not.


Some of the elements along the jagged Some of the elements along the jagged line are a special case called line are a special case called metalloids.metalloids.

B, Si, Ge, As, Sb, Te and Po are B, Si, Ge, As, Sb, Te and Po are metalloids. Metalloids behave like metalloids. Metalloids behave like metals in some ways, but also like metals in some ways, but also like nonmetals in some ways.nonmetals in some ways.

NaNa

Find Na on the table.Find Na on the table.

Na stands for sodium. Sodium is one of those Na stands for sodium. Sodium is one of those elements that we’re going to use over and over elements that we’re going to use over and over this year. Might as well memorize it now.this year. Might as well memorize it now.

Of course that makes no sense, unless you know Of course that makes no sense, unless you know that the Latin name for sodium is natrium, and that the Latin name for sodium is natrium, and then it makes a lot more.then it makes a lot more.

Why did we give it a Latin name? Well, this Why did we give it a Latin name? Well, this British guy named Sir Humphry Davis gave it that British guy named Sir Humphry Davis gave it that name back in 1807 when he discovered it.name back in 1807 when he discovered it.

KK

Right underneath sodium is K or potassium. Right underneath sodium is K or potassium. Ok, does that have a Latin name too? Yes, Sir Ok, does that have a Latin name too? Yes, Sir Davis discovered this too and he named it Davis discovered this too and he named it kalium.kalium.

Why? I don’t know but the guy that Why? I don’t know but the guy that discovered it got to name it and that’s what discovered it got to name it and that’s what he decided to name it.he decided to name it.

Based on your understanding of maps do you Based on your understanding of maps do you think K has a little or a lot in common with think K has a little or a lot in common with Na?Na?

Alkali MetalsAlkali Metals

Sodium and potassium and all the rest of the Sodium and potassium and all the rest of the elements in that group are alkali metals.elements in that group are alkali metals.

The alkali metals all have one valence The alkali metals all have one valence electron. That similarity is what makes them electron. That similarity is what makes them behave the same chemically.behave the same chemically.

They are very reactive. Reactivity is highest They are very reactive. Reactivity is highest on the outer edges of the table and elements on the outer edges of the table and elements get less reactive the closer they are to the get less reactive the closer they are to the center of the table. Lithium is the least center of the table. Lithium is the least reactive alkali metal and reactivity increases reactive alkali metal and reactivity increases as you go down the group.as you go down the group.

Noble GasesNoble Gases

The noble gases are very stable. They are The noble gases are very stable. They are unreactive because they are so stable.unreactive because they are so stable.

The noble gases all have 8 valence electrons. The noble gases all have 8 valence electrons. Helium is an exception in that it only has 2.Helium is an exception in that it only has 2.

The noble gases are obviously gases at The noble gases are obviously gases at normal room temperature.normal room temperature.

Alkaline Earth Metals Alkaline Earth Metals & Halogens& Halogens

Group IIA or Group 2 are called “the alkaline Group IIA or Group 2 are called “the alkaline earth metals.” They have 2 valence earth metals.” They have 2 valence electrons.electrons.

Group VIIA or Group 17 are called “the Group VIIA or Group 17 are called “the halogens.” The halogens all have 7 valence halogens.” The halogens all have 7 valence electrons, and like the alkali metals, they are electrons, and like the alkali metals, they are very reactive (fluorine is most reactive and very reactive (fluorine is most reactive and reactivity decreases as you go down the reactivity decreases as you go down the group). group).

Customize your tableCustomize your table

Highlight the s block in BLUEHighlight the s block in BLUE

Highlight the p block in ORANGEHighlight the p block in ORANGE

Highlight the d block in YELLOWHighlight the d block in YELLOW

Highlight the f block in PINKHighlight the f block in PINK

Circle the element symbols for the gases.Circle the element symbols for the gases.

Draw a square around the symbol for Hg and Br. These Draw a square around the symbol for Hg and Br. These are the only 2 liquids at room temperature.are the only 2 liquids at room temperature.

Put a * in the box for H, O, N, Cl, Br, I, and F. These are Put a * in the box for H, O, N, Cl, Br, I, and F. These are diatomic elements.diatomic elements.

As you learn more, continue to customize your periodic As you learn more, continue to customize your periodic table.table.

Power Point AssignmentPower Point Assignmenthttp://sciencespot.net/Media/ptablebasics.pdfhttp://sciencespot.net/Media/ptablebasics.pdf

Get the Periodic Table Basics Assignment from Get the Periodic Table Basics Assignment from meme. (I found this assignment at sciencespot.net, . (I found this assignment at sciencespot.net, and special thanks to Tracy Trimpe for not having and special thanks to Tracy Trimpe for not having to reinvent this wheel.)to reinvent this wheel.)

Do the assignmentDo the assignment. You will turn in the questions . You will turn in the questions on the back PLUS a simplified version of the on the back PLUS a simplified version of the Periodic Table that you will make in the Periodic Table that you will make in the assignment.assignment.

To do this assignment, you need to know what a To do this assignment, you need to know what a Bohr Diagram is and what a Lewis structure is.Bohr Diagram is and what a Lewis structure is.

Continue on to find out.Continue on to find out.


A Bohr diagram shows the electrons in “energy A Bohr diagram shows the electrons in “energy levels.”levels.”

The energy levels are represented by circles. The The energy levels are represented by circles. The inner most circle can have 2 electrons. The other inner most circle can have 2 electrons. The other outer circles, can have a total of 8 each.outer circles, can have a total of 8 each.

You represent the electrons with a dot, starting on You represent the electrons with a dot, starting on the inner circle, filling that up, and then moving the inner circle, filling that up, and then moving outward. You must fill the circle completely outward. You must fill the circle completely before you can move to the next circle.before you can move to the next circle.

The assignment gives you an example using The assignment gives you an example using Boron.Boron.


Once you have the Bohr diagram done, the Lewis Once you have the Bohr diagram done, the Lewis structure is very easy.structure is very easy.

You represent only VALENCE electrons on the You represent only VALENCE electrons on the Lewis structure.Lewis structure.

Valence electrons are electrons which are in the Valence electrons are electrons which are in the highest occupied energy level. In other words, highest occupied energy level. In other words, the electrons in the outermost circle in your Bohr the electrons in the outermost circle in your Bohr diagram are valence electrons.diagram are valence electrons.

They give you an example using Boron. B has 3 They give you an example using Boron. B has 3 electrons in the outer circle, so the Lewis electrons in the outer circle, so the Lewis structure has 3 dots.structure has 3 dots.

Power Point AssignmentPower Point Assignmenthttp://www.ausetute.com.au/lewisstr.htmlhttp://www.ausetute.com.au/lewisstr.html

A Lewis structure can have a maximum of 8 A Lewis structure can have a maximum of 8 dots.dots.

You put one dot on each side of the symbol You put one dot on each side of the symbol (top, bottom, left and right), until each side (top, bottom, left and right), until each side has a dot.has a dot.

Then you can start pairing them up, until Then you can start pairing them up, until every side has 2 dots.every side has 2 dots.

When every side has two dots, you can’t put When every side has two dots, you can’t put any more dots on the structure. If you need any more dots on the structure. If you need to, you did something wrong.to, you did something wrong.

OxygenLewis structure

The EndThe End

Next you should look at the Chemical History power Next you should look at the Chemical History power point.point.Then…Then…

Advanced Chemistry should go to Chapter 28 Advanced Chemistry should go to Chapter 28 powerpoint.powerpoint.

Chemistry should go to the Special Topics for Chemistry should go to the Special Topics for SOL 2SOL 2

powerpoint.powerpoint.

Chapter 5

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Transcript of Chapter 5